An Empirical Analysis of Offshore Service Vessel Utilization in the US Gulf of Mexico

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An empirical analysis of offshore service vessel utilization in the US Gulf of Mexico Mark J. Kaiser and Brian Snyder Center for Energy Studies, Louisiana State University, Baton Rouge, Louisiana, USA

Received 26 June 2009 Revised 7 January 2010 Accepted 2 February 2010

Abstract Purpose – The offshore supply vessel (OSV) industry is critical to offshore oil and gas operations around the world and contributes to the economic and ecological impacts experienced by the local communities supporting the offshore oil and gas industries. The OSV industry has not been studied significantly and the economic and ecological impacts to local communities is generally unknown. This paper aims to address these issues. Design/methodology/approach – In this paper, the authors review the activities and logistical require req uirement mentss inv involve olved d in offs offshore hore exp explor loratio ation n and dev develop elopmen mentt wit with h spe specia ciall atte attentio ntion n paid to workflows and the manner in which service vessels are utilized in the Gulf of Mexico. The authors estimate the OSV needs per stage of activity for offshore operations based on data collected from company planning documents, fleet utilization data from oil and gas companies and service providers, interviews and surveys. The statistical data is synthesized and reconciled and despite large variances the data sources are in reasonable agreement. Empirical data on circuit factors are also provided. The applications and limitations of the analyses are discussed. Findings – In the US GOM, a large variety of marine vessels transport goods and provide services to exploration, development and production activity. OSVs provide a vital link between offshore E&P activities and shore-based facilities. Offshore oil and gas operations cannot function without them and their utilization and spatial distribution provide a way of understanding the impacts of the offshore oil and gas industry on coastal communities. service vessel industry. industry. The Originality/value – This is the first empirical analysis of any offshore service data da ta pr pres esen ente ted d he here re ca can n be us used ed to pre predic dictt th thee en envi viro ronme nment ntal al,, ec econo onomic mic,, pub publi licc he heal alth, th, and infrastructural consequences of alternative offshore development policies. structures, es, Vessels, Ecology, Offshore construc construction tion works, Keywords Maritime structur United States of America

Paper type General review

InternationalJournal of EnergySector InternationalJournal Management Vol. 4 No. 2, 2010 pp. 152-182 q Emerald Group Publishing Limited 1750-6220 DOI 10.1108/17506221011058687

1. Introduction Offs Of fshor horee su suppl pply y ve vess ssel elss (O (OSV SV)) are an im impor portan tantt par partt of oi oill and gas op opera erati tion onss worldwide and in the Gulf of Mexico (GOM). The offshore service industry provides goods and services to offshore activities. These services involve moving personnel to, from, and between offshore installations and rigs; delivering supplies, equipment, fuel, water, and food; towing rigs and placing and retrieving rig anchors; and supporting offs of fshor horee con const struc ructi tion on pro proje ject cts. s. Al Altho thoug ugh h ea each ch op opera eratio tion n is un uniq ique ue and jo job b spe speci cific fic,, th there ere is al also so a co comm mmon onal alit ity y to al alll of offs fsho hore re ac acti tivi vity ty,, wh whet ethe herr it oc occu curs rs in th thee GO GOM M or an any y ot othe herr offshore basin worldwide[1]. Supply vessels support all exploration and production operations operati ons includ including ing explorat exploration, ion, devel development, opment, production, and abandonme abandonment. nt.

The logistics of offshore oil and gas operations are critically important to their success, but have not been widely addressed in the academic literature because of the complexity of the operations and the difficulty of correlating service vessel use to offshore activity. Academic study of offshore logistics has focused on quantitative al.., 200 al.., 2007 models of ship and helicopter helicopter movement (Romero (Romero et al 2007; 7; Aas Aas et al 2007;; Fagerholt Fagerholt and Lin Lindst dstad, ad, 2000 2000;; Gri Gribkov bkovskai skaia a et al 2007 07), ), fle fleet et de desi sign gn (A (Aas as et al 2009) 9),, al.., 20 al.., 200 al.., 2005 informa inf ormatio tion n mana managem gement ent (Hu (Hull, ll, 2002 2002;; Hol Hollan land d et al 2005), ), out outsour sourcing cing deci decision sion making (Aas et al., 2008; Finch, 2002), sustainability (Matos and Hall, 2007), market barriers (Cairns and Harris, 1988), spatial issues (Parola and Veenstra, 2008; Fremont, 2007; Ahmed and Miller, 2007) and facility siting policy (Gale and Albright, 1993; Randle,, 1981; Price, 1987). The study of the logistics Randle logistics of the upstream offshore industry industry has bee been n div divers erse, e, but not the theoret oretica ically lly uni unified fied or wel welll dev develop eloped. ed. Emp Empiri iricall cally y sup support ported ed models and analysis have also not been pursued. As a result, the number of OSV trips needed to support a specific type of activity is not known. This basic information is necessary for addressing a variety of academic, planning and policy issues and is the motivation for this work. On the USA oute outerr cont contine inental ntal she shelf[ lf[2] 2] (OC (OCS), S), min mineral eral res resourc ources es are adm admini inister stered ed and leased to exploration and production (E&P) companies by the Minerals Management Service (MMS), a branch of the Department of the Interior. The MMS is required to conduct environmental studies to assess the impact of oil and gas development on the human, marine, and coastal environment of affected OCS and coastal areas. As part of these Environmental Impact Statements, the MMS estimates the number of service trips that arise from shore and their socioeconomic impact (for further details, see the Appendix). The offshore logistics network in the GOM is a complex and dynamic system with a diverse collection of work activities performed by hundreds of contractors across a broad time and space continuum (Figure 1). Durations of involvement range from transitory to short-term to time horizons that extend into decades. Activities occur over

Louisiana

Empirical analysis of OSV utilization

153

Mississippi

Texas Sabine

Cameron

New Iberia

Theodore

Morgan City Houma

Freeport

Galveston

Intracoastal/ freshwater

Venice Fourchon

Aransas

Port Isabel

Figure 1. Primary E&P relat related ed shorebases in the GOM

The logistics of offshore oil and gas operations are critically important to their success, but have not been widely addressed in the academic literature because of the complexity of the operations and the difficulty of correlating service vessel use to offshore activity. Academic study of offshore logistics has focused on quantitative al.., 200 al.., 2007 models of ship and helicopter helicopter movement (Romero (Romero et al 2007; 7; Aas Aas et al 2007;; Fagerholt Fagerholt and Lin Lindst dstad, ad, 2000 2000;; Gri Gribkov bkovskai skaia a et al 2007 07), ), fle fleet et de desi sign gn (A (Aas as et al 2009) 9),, al.., 20 al.., 200 al.., 2005 informa inf ormatio tion n mana managem gement ent (Hu (Hull, ll, 2002 2002;; Hol Hollan land d et al 2005), ), out outsour sourcing cing deci decision sion making (Aas et al., 2008; Finch, 2002), sustainability (Matos and Hall, 2007), market barriers (Cairns and Harris, 1988), spatial issues (Parola and Veenstra, 2008; Fremont, 2007; Ahmed and Miller, 2007) and facility siting policy (Gale and Albright, 1993; Randle,, 1981; Price, 1987). The study of the logistics Randle logistics of the upstream offshore industry industry has bee been n div divers erse, e, but not the theoret oretica ically lly uni unified fied or wel welll dev develop eloped. ed. Emp Empiri iricall cally y sup support ported ed models and analysis have also not been pursued. As a result, the number of OSV trips needed to support a specific type of activity is not known. This basic information is necessary for addressing a variety of academic, planning and policy issues and is the motivation for this work. On the USA oute outerr cont contine inental ntal she shelf[ lf[2] 2] (OC (OCS), S), min mineral eral res resourc ources es are adm admini inister stered ed and leased to exploration and production (E&P) companies by the Minerals Management Service (MMS), a branch of the Department of the Interior. The MMS is required to conduct environmental studies to assess the impact of oil and gas development on the human, marine, and coastal environment of affected OCS and coastal areas. As part of these Environmental Impact Statements, the MMS estimates the number of service trips that arise from shore and their socioeconomic impact (for further details, see the Appendix). The offshore logistics network in the GOM is a complex and dynamic system with a diverse collection of work activities performed by hundreds of contractors across a broad time and space continuum (Figure 1). Durations of involvement range from transitory to short-term to time horizons that extend into decades. Activities occur over

Louisiana


153

Mississippi

Texas Sabine

Cameron

New Iberia

Theodore

Morgan City Houma

Freeport

Galveston

Intracoastal/ freshwater

Venice Fourchon

Aransas

Port Isabel

Figure 1. Primary E&P relat related ed shorebases in the GOM

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all possible spatial dimensions from point activities to large one and two-dimensional region reg ionss (in (insta stalli lling ng pip pipeli eline ne and sei seismi smicc sur surveyi veying) ng).. Many sys system tem com compone ponents nts and work processes vary with water depth and have evolved with changes in technology and business arrangements. Hundreds of operators and service companies operate in the Gulf and have the option of using a variety of shorebases and vessel types to service their activity. Thee lev Th level el and fre freque quenc ncy y of ons onshor horee sup suppo port rt (l (labo aborr and mat materi erial al req requi uirem rement ents) s) depends upon the life cycle stage of the work activity (e.g. exploration and production), the type of activity (e.g. sidetracking a well and installing flowline), site characteristics (e.g., location, age, facility type, production level and type, maintenance schedule), the occur occ urren rence ce of exo exoge genou nouss eve events nts (e (e.g .g.. hu hurri rrica cane ne act activ ivity ity,, oil sp spil ills ls and rec recove overy, ry, ac accid ciden ents ts), ), and othe otherr fact factors. ors. Some acti activiti vities es are esse essentia ntially lly self-conta self-contained ined,, in whic which h the work activity does not require – or requires only a minimum – of onshore support during the executi exe cution on of the acti activit vity. y. Seis Seismic mic surveying surveying and site clearance clearance and veri verificat fication ion are examples of activities that require minimal onshore support. Installation, drilling and production operations occur over longer time horizons with more substantial material requirements, involving regular and frequent onshore support. OSVs are known as the “workhorse” of the industry and the “trucks” of the ocean, while crewboats mainly function to transport personnel to and from manned platforms and rigs. OSVs and crewboats comprise the majority of the marine vessels in the GOM and are the focus of this paper. OSVs are designed to carry a wide variety of cargo, utilizing space both above and below deck to carry supplies. With its wide-open bay (“well”) astern, high bow and forward accommodation, the OSV is ideally suited for the storage and delivery of contai con tainers ners,, dri drill ll pip pipe, e, tub tubing ing,, anch anchors, ors, and othe otherr heav heavy y and ove oversi rsized zed equ equipm ipment ent (Plate 1). 1). Below deck, a refrige refrigerated rated cargo hold and special special-purpose -purpose tanks tanks facilitates facilitates the transportation of food, drinking or industrial water, diesel fuel, drilling fluids, mud, cement, methanol, and other material. OSVs generally range from 160 to 260 feet in length and travel at 10 to 12 knots (Aas et al., 2009). Crewboats are used to transport crews between offshore installations or near-shore loca lo cati tion ons. s. Cre Crewb wboat oatss are sm smal alle lerr th than an OS OSVs Vs and ran range ge in si size ze fr from om 75 to 190 fe feet et (P (Pla late te 2) 2).. Older crewboats (circa 1980s build) are typically 100-120 feet in length, while newer crewboats are generally larger, 130-165 feet in length, travel at greater speed with more cargo carrying capacity (Barrett, 2008). New generation crew boats called fast supply vessels can also carry a limited amount of supplies in addition to transporting crews. The utilization of OSVs varies depending on the needs and size of the contracting compa co mpany ny.. Th There erefor fore, e, ge gene neral ralit itie iess on th thee us usee of OS OSVs Vs is di diffic fficul ult. t. Th There ere is no si sing ngle le mo most st reliable source of data to estimate OSV needs. Ideally, a random subsample of OSV operating companies categorized by developmental activity and containing detailed information on the activities of ships engaged in support of each developmental stage would wo uld be col colle lect cted ed;; th thee dat data a wou would ld cov cover er at le leas astt one ye year ar and wo woul uld d be spa spati tial ally ly di dive vers rsee including both shallow and deepwater regions throughout the GOM, and it would include a heterogenous mix of operators from small independents to super-majors. No such data source is publicly or commercially available. Therefore, it was necessary to collect colle ct and analyze analyze a variety variety of diverse diverse data sources and to synthes synthesize ize and and reconcile reconcile the the resulting information. We reviewed company plan data, conducted interviews and


155

Note:

A 240 feet OSV Source: Harvey Gulf International

Note: A

100 feet crewboat Source: Photo by Authors

Plate 1. The Harvey Provider

Plate 2. M/V Dyan J

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surveys, and acquired detailed information from several E&P companies and one OSV company on their fleet use. The purpose of this paper is to assess average patterns of OSV use during different phases of oil and gas development in the US sector of the GOM. We quantify the number of trips per week needed for drilling, development, production, and decommissioning. We begin with an overview of the work processes and vessel requirements across the primary stages of E&P activity. We analyze several independent sources of data on OSV utilization and compare the utilization estimates. Special attention is paid to the limitations of the analysis.

2. E&P life cycle stage Broadly speaking, four stages of E&P activity are commonly identified: (1) exploration; (2) development; (3) production; and (4) decommissioning. The search for oil and gas begins with exploration. Development represents a transitional stage between exploration and production. Abandonment is the end state where the wells are plugged and infrastructure removed and the site returned to pre-lease conditions. Various activities occur within each of the main stages, and within each subcategory, a variety of applications are found with activities that overlap and marine vessel requirements that differ in magnitude and timing. The objective of this section is to provide a summary overview of the activities and logistical requirements involved in offshore E&P with special attention paid to work flows and the manner service vessels are utilized. This discussion is meant to highlight the work processes and vessel requirements across each of the main stages of operation and not as a comprehensive survey of offshore activity.

2.1 Exploration The objective of exploration is to find oil and gas reservoirs that can be commercially developed. The two primary types of field activity that occur during exploration include geophysical surveying and exploration drilling. Geophysical surveying . Seismic operations often take place at the front end of the exploration process, and as a field is developed, crews may revisit the area for short periods of time. Geophysical seismic surveys are performed to obtain information on surface and near-surface geology and on subsurface geologic formations. Seismic surveys collect data on surficial geology used to identify potential shallow geologic hazards for engineering and site planning. Most operations are reasonably self sufficient and only require helicopters for crew change and minimum marine vessel support. Work rotation schedules of five weeks on/off mean that flights to the vessel are infrequent. Exploratory drilling . Exploration drilling activities are conducted by contractors operating under the supervision of a leaseholder/operator. Exploration drilling may last from several weeks to a few months in duration per well, and more than one well may be drilled at location. Exploration wells may be drilled from existing platforms,

but most are drilled from mobile offshore drilling units (MODUs) such as jackups, semisubmersibles, or drillships. Rigs require a steady stream of material when drilling a well, due to the physical limits on the amount of material they can store. Modern drillships are able to store large quantities of equipment and materials, and require significantly less logistical support than rigs and semisubmersibles, which must be supplied by service vessels or risk shutting down operation. Generally, one or more dedicated OSVs are contracted to maintain rigs in operation for the duration of the activity, and afterwards, are released to the market to find another contract. Jackups and semisubmersibles generally require seagoing tugs for towing between drillsites and for location during mooring and unmooring operations. While many semisubmersibles have on-board thrusters to assist, most rely on a spread mooring system for maintaining position during drilling. Anchor handling, towing, and supply (AHTS) vessels (Plate 3) tow rigs from one location to another and are equipped with powerful winches to lift and position the rig’s anchors. AHTS vessels may arrive directly from an onshore base, or if in the field, from another job.


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2.2 Development If the results from exploratory drilling appear promising, additional wells will be drilled to delineate the field and development wells drilled for production. Production facilities are designed, fabricated, and assembled in yards throughout the world, and

Note: A

267 feet AHTS Source: GNU free documentation license

Plate 3. Normand Master

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then transported to site. Geophysical surveys are carried out to support development drilling and the location and installation of production facilities and pipelines. The time needed to design, construct, and install the physical infrastructure to produce hydrocarbons may be as little as six months or less for a caisson (one well system with flowline) to two years for a major platform to a decade or more for deepwater systems with subsea wells. The duration of installation may range from a few weeks to several months, depending on the complexity of the system components. Structure installation. In shallow water, caisson and fixed platform installations have well-established time tables because of the similarity and maturity of design concepts. In deepwater, a variety of different structural elements exists which require different methods of transportation and installation. Deepwater fields are developed on a stand alone basis, as a central processing (host) platform, or as a satellite field tied back to a host platform. The well system and drilling operations are functionally similar to shallow water and onshore, but systems and installation procedures are structurally different. The spatial relationship between system components and construction equipment selection will influence the timing and sequence of activities. Details of installation schedules will vary, especially when the same construction equipment is selected for different activities, but the overall effort will likely by similar. The activities associated with drilling, completion, and hookup of subsea wells are essentially the same as those associated with exploration drilling. Pipeline installation. Oil and gas is transported by a system of pipelines from the point of extraction to the point of consumption. The amount and type of supply, the nature of its decline, and the potential for nearby discoveries, as well as the environment and distance over which fluids have to be transported, determine the design of the system. Three type of pipelines are utilized: gathering systems, tie-ins, and trunklines. Gathering lines are typically short segments of small diameter pipelines that transport materials from one or more wells to a production facility or from a production facility to a trunkline. Trunklines are typically large-diameter pipelines that transport production from many wells and several fields to shore. Pumps and compressors add energy to the fluid to ensure that it will flow to its destination or the next pumping or compression station. Pipelaying methods depend on environmental conditions[3], availability and cost of equipment, length and size of line, water depth, and constraints of adjacent lines and structures (Gerwick, 2007). The most common techniques include the S-lay barge, bottom-pull method, reel barge, and J-tube from platform. The operations, sequence of activities, duration, equipment, and vessel requirements vary with each technique. Before pipeline is layed, bathymetric and side scan sonar surveys are required to avoid colliding with reefs and other seafloor disturbances. Rate of progress depends on the lay barge type, crew experience, and weather. The longer the barge, the greater the number of welding stations, and the faster the progress. Lay barges have limited capacity to store pipe and so pipe must be loaded regularly from the shore, transported to site, and unloaded. In moderate sea states, a barge can be tied off alongside the lay barge, but in heavier sea states, supply boats are used.

2.3 Production After the support structure and topsides equipment is installed and commissioned, production may last from a few years to several decades. For a manned facility, essentially all future activities will be confined to the platform. The frequency of supply boat visits will vary depending on the amount of production and the age of the structure but once per week during normal operations is typical. More frequent visits normally occur during initial startup, drilling activities, equipment changeout, and workover operations. For unmanned platforms and satellite developments, supply boats will make periodic visits to provide logistical support, often once or twice a week, or on an as-needed basis depending on the level of automation and maintenance requirements. Helicopters are also frequently used to transport crews to unmanned facilities for inspection and repair. Drilling, completion, and workover activities associated with subsea tiebacks are carried out from MODUs, which may stay on location for periods ranging from a few days to several weeks, depending on the nature of the operation. Subsea maintenance work on wellheads or other subsea components will require mobilization of a drilling rig or other construction vessel. The duration of these activities will vary widely, but the equipment and nature of the operations are similar to exploration drilling and installation activities. Workover operations can be performed in many different ways using different vessel types. 2.4 Decomissioning Once the facility stops production and ceases to serve a useful purpose, the site will be abandoned and the lease will revert to the government. Decommissioning is a highly prescribed process which begins when notice is given that the lease has ceased production. An operator has six months to notify MMS when production has ceased on a lease, and from the point of notification of cessation of production, the operator has one year to clear the lease of all facilities. The nature of the activities and the equipment involved in abandonment are generally similar to those involved in installation but require less time. Wells will be plugged and abandoned in accordance with federal regulation, and performed using a wire-line unit, drilling rigs, workover rigs, or coiled tubing units. In a typical removal operation, a heavy lift vessel arrives at site and AHTS vessels set up anchor. Cargo barges are towed to site to accept the deck and jacket structure. Removal operations follow the installation process in reverse. Cranes lift the deck in one or more sections and secures the load to a cargo barge. The jacket is lifted and removed from the seabed, and the deck and equipment is transported to an onshore fabrication yard or storage facility. The jacket can be taken to shore for storage or scrap, taken to a designated reef site, or topped in place. After the platform is removed, the area is cleared of debris and clearance is verified with specially equipped trawlers with nets. Debris from around the platform site is cleared and sent to shore for disposal. Selection of equipment and procedures employed in decommissioning depend on many of the same factors that influence selections for installation, including availability and cost. The duration of work will usually range from two or three weeks for removal activity. As in the case of installation, certain decommissioning activities can be carried out simultaneously.


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3. Data sources OSVs are usually assigned to either a drilling or production pool with boats in the production pool under long-term contracts (perhaps six months to a year) and boats in the drilling pool on shorter term (approximately three months) contracts. Larger E&P companies may contract several boats and use them as a pool among several production projects whereas smaller companies are likely to use a dedicated boat. Often, a manned production platform is linked to several nearby wells protected by caissons and well protector structures. The OSV first visits the manned platform and over the course of the day may ferry men and supplies to the nearby fields. The data sources used and their reliabilities in terms of “completeness” and “accuracy” are summarized in Table I. Completeness refers to the ability of the data to estimate activity throughout the GOM and the extent to which the data is biased by small sample size. Accuracy refers to the probability that the data is correct in its individual estimations. For example, the BP data is considered to have poor completeness due to its focus on deepwater activities, but good accuracy since we believe it to be an accurate measure of all trips in its sample. The data sources listed in Table I and their varied strengths and weaknesses are described in detail later. There are two main classes of data analyzed: data from MMS plans and data provided by companies. Plan data describes the activity that the operator expects to occur in a particular development; company data describes actual operational data. Individually, while not particularly informative, taken together they provide a reasonable representation of OSV activities. While none of the collected data meets all the criteria of an ideal data source, the plan and BP data are of relatively long temporal duration, the plan data is spatially diverse covering the entire GOM, the BP and

Data name

Data source

Completeness Accuracy Limitations

Simple data

MMS DOCD and EP plans

Good

Poor

Detailed data

MMS DOCD plans

Good

Medium

Apache

Apache ship use data for first four months of 2008

Medium

Medium

BP

Table I. Data sources and their relative quality

BP ship use data Poor for 2008 CShip use data from Medium Logistics an OSV operator

Good

Interview Interviews with industry participants

Medium

Poor

Good

Requires assumptions on developmental stage Reports engineering estimates, not actual movements Covers only Fourchon and only first four months of year; no production Primarily deepwater activity Primarily deepwater drilling data O nly interviewed small sample of total industry participants

Reasonable applications Drilling and production

Production, drilling, and construction Drilling, construction, and P&A Deepwater production Deepwater drilling and both shallow and deepwater production Check on reasonableness of other estimates

C-Logistics (CL) data are deepwater focused, and the BP and Apache data include a number of developmental phases including abandonment. There are other sources of marine commerce data available, including data from the Army Corps of Engineers and the automatic identification system (AIS), which track ship movements using surveys and transponder signals. These data sources are not useful for determining the number of vessels used for a particular developmental activity, and only provide information on vessel movements without reference to oil and gas developmental stages. Throughout the paper we generally refrain from detailed statistical analyses or advanced methodologies in favor of reporting means and standard deviations. We choose to do so for two reasons. First, the variances in the data are generally very large relative to the means, making statistical analyses uninformative. Second, the paper is intended to provide base and explanatory data, not to test hypotheses or build sophisticated models on relative OSV usage.


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4. Plan data When E&P companies plan to undertake activities in the GOM (exploratory or developmental drilling, well completion, construction and installation, pipeline installation, and commencement of production) they are required to complete either an exploration plan (EP) or a Development and Operations Coordination Document (DOCD). EP plans are required for exploratory drilling, while DOCD plans are required for developmental drilling, installation, and commencement of production. In some cases, plans report detailed information on the number of days and hours vessels are expected to be operating in the GOM. However, not every plan is required to submit detailed information on vessel activity. Table II shows a checklist of questions

(A) Emissions worksheets and screening questions Screen procedures for DOCD’s If any calculated complex total (CT) emission amount (tons) associated with your proposed development activities more than 90 percent of the amounts calculated using the following formulas: CT ¼ 3,400D2/3 for CO, and CT ¼ 33.3D for the other air pollutants (where D ¼ distance to shore in miles)? Do your emission calculations include any emission reduction measures or modified emission factors? Does or will the facility complex associated with your proposed development and production activities process production from eight or more wells? Do you expect to encounter H 2S at concentrations greater than 20 parts per million (ppm)? Do you propose to flare or vent natural gas in excess or criteria set for the under 250.1105(a)(2) and (3)? Do your propose to burn produced hydrocarbon liquids? Are your proposed development and production activities located within 25 miles (40 kilometers) from shore? Are your proposed development and production activities located within 124 miles (200 kilometers) of the Breton Wilderness Area?

Source: MMS DOCD plan

Yes

No

X X X X X X X X

Table II. Sample screening questions from DOCD plans

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Figure 2. Example of the form that must be completed in DOCD plans by E&P companies

that must be answered in EP and DOCD plans. If the E&P company answers any of these questions affirmatively, then they must submit a detailed account of the number of operating vessels and the number of days and hours per day those vessels are operating by activity. This data is referred to as “detailed data” and Figure 2 is an example of the form E&P companies must complete. If the E&P company answers no to all the questions listed in Table II, then they only have to report the number of crew and supply vessel trips per week without reference to the stage of development during which the trips are occurring. We refer to this data as “simple data”; Table III provides an illustration of a sample table. Companies that provide detailed data are required to provide the simple data that all companies must provide. Therefore, plans contain two types of potentially useful and ambiguous information on the number of OSV trips.

Source: MMS

DOCD Plan

The first EP and DOCD plans a company submits are referred to as initial plans. As planning evolves and changes, operators submit supplemental and revised plans. A supplemental plan is a revision to an approved plan that proposes the addition of an activity that requires a permit. A revised plan is a revision to an approved plan which proposes changes such as the location of a well or onshore service base. Supplemental plans may contain two kinds of detailed data, aggregate data on total plan emissions and data on only the supplemental plan emissions. We used only the supplemental plan emissions data with the supplemental plan activities and did not use the total aggregate emissions. This allowed us to use both supplemental and initial plans without fear of double counting trips. Trip data from both the simple and the detailed data are estimates made by engineers and do not reflect the actual number of trips. They are often considered to be conservative estimates so that if errors in emission estimates are made the emissions are overestimated rather than underestimated. The estimates are stated in the plans not in terms of the number of trips, but the number of days vessels will be needed[4]. Unless otherwise stated, we assume that for the simple and detailed data the number of days boats are needed is equivalent to the number of times a boat leaves port and the terms boat days and trips are used interchangeably. As a result, the plan data may overestimate the number of trips but this can be corrected for by the use of circuitry factors, discussed later.


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4.1 Simple data The simple data in DOCD and EP plans usually report only the number of days supply and crew boats are needed but does not report the operational phase for which these boats are needed. We analyzed simple data collected from 1,261 DOCD and EP plans. This dataset included all plans filed from January 2005 through July 2008 and a random subsample of 50 plans per year from January 1, 2001 to December 31, 2004. The data set does not include duplicate plans which are filed when a lease contains more than one area block. OSV trips. Comparing the number of trips reported in the simple data with the number of trips reported in the detailed data showed that simple data table numbers were generally the maximum number of trips needed over the multiyear period the plans covered. This makes analysis of the simple data difficult because plans contain multiple activities (pipelaying, drilling, and production) and we do not know which period the reported simple data represents. Therefore, we categorized the 1,261 plans according to whether they contained drilling, construction, or pipelaying activities and analyzed the OSV requirements within each category (Table IV).

Type Supply boats Crew boats Aircraft

Maximum fuel tank storage capacity (bbls)

Maximum number in area at any time

500 500 1,900

1 1 1

Note: This is the basis of the simple data used in the analysis Source: MMS DOCD plan

Trip frequency or duration Once a week Once a week As needed

Table III. Sample table from DOCD plans

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Construction

Pipelines

Activitya

N N Y Y

N Y N Y

164

N N N N No drilling total Y Y Y Y With drilling total

N N Y Y

N Y N Y

Production Pipelines Unclear Unclear Unclear Drilling Unclear Drilling Unclear Drilling

Table IV. Average crew and supply boat needs in vessel trips per week

Crew boat

Supply boat

Sample size

1.9 (1.9)b 2.6 (1.2) 1.9 (2.2) 2.1 (1.9) 2.0 (2.0) 3.5 (2.1) 4.1 (3.1) 4.0 (2.5) 3.7 (2.1) 3.8 (2.3)

1.9 (1.8) 2.5 (2.0) 1.8 (1.6) 1.8 (1.4) 1.8 (1.7) 3.3 (1.8) 2.9 (1.7) 3.3 (1.8) 3.0 (1.5) 3.3 (1.8)

81 21 96 65 263 448 10 438 102 998

Notes: aActivity means the developmental stage, we assume the data generally represents; this is based on the assumption that simple data reports the maximum number of trips needed over all of the activities included in the plan and that drilling requires more OSV use than production; bstandard deviations in parentheses Source: MMS DOCD and EP plan simple data

The standard deviations are large and roughly the size of the means. The first row in Table IV in which there is no construction, drilling or pipe laying represents those plans in which the E&P company sought to commence production. The values of 1.9 crew boats per week and 1.8 supply boats per week are considered to be the average needs during production. The sixth row of Table IV in which construction and pipe laying do not occur represents the number of vessels needed during drilling. This assumes that E&P companies report the maximum number of boats needed at any one time and that drilling requires more vessels than production. That is, it assumes that when a plan contained both drilling and production, the OSV needs from drilling were reported. Limitations of simple data. The simple data is a large data set that is potentially informative but has limitations. Simple data does not refer to which stage of development the data describe and as a result assumptions linking developmental phase and OSV data must be made. Despite this limitation, however, the mean crew and supply boat usage agree relatively well. For example, the crew and supply boat needs in the first four rows of Table IV (in which drilling does not occur) are all relatively constant at around two boats per week. Similarly, the data in the next four rows in which drilling occurs suggest about four crew boats and three supply boats are needed per week. This consistency among differing plan types suggest that the averages for plans with drilling and plans without drilling (“no drilling total” and “with drilling total” in Table IV) may be good estimates of OSV needs during drilling and production. The simple data covers a long time span including several active hurricane seasons, the ongoing responses to the destruction caused by these hurricanes, low oil prices of 2001 through 2003, and the very high prices of 2006 through 2008. The data does not capture any time dependency or directly reflect such environmental conditions since, as mentioned previously, they are estimates of expected activity as opposed to the measurement of actual activity. The temporal duration generates a large sample size and reduces the potential impact of aberrational reporting on overall estimates.

4.2 Detailed data A total of 311 DOCD plans were reviewed for information on the number of service vessels required in offshore E&P activity. The 311 plans represent every DOCD plan filed between October 1, 2006 and October 1, 2008. The data set includes supplemental plans but not duplicate plans. Of the 311 plans, 220 reported some type of detailed data. Drilling . Out of the 311 plans analyzed, only 95 contained both drilling and detailed information on the number of vessels needed. We determined average water depths for these 95 plans, summed the numbers of vessels needed across years to determine a total number of vessels needed per well, divided the number of vessels by the number of weeks spent drilling and the number of wells drilled to determine the number of vessels used per well per week and then subdivided into shallow (less than 1,000 feet water depth) and deepwater (greater than 1,000 feet water depth) categories. These data are presented in Table V. As expected, the duration of drilling and supply vessel needs are greatest in deepwater, however, crew boat use declines in deepwater drilling, likely due to the use of helicopters to ferry personnel and utilization of larger boats. Development . Construction support data is more complex than the other data analyzed due to the different types of construction. Table VI depicts basic information on construction data. On average, it takes about ten days to install structures in the GOM: 13 days for platforms, nine days for caissons. Out of the 311 plans reviewed, 181 included some construction. Of these 181 plans, 84 did not report specific vessel movements. Furthermore, many of the plans included vessel information for the installation of more than one type of facility (for example, a caisson and production facilities). We removed these plans from the analysis because we could not determine which boats were needed for which type of construction activity. Water deptha Shallow Deep Total

Time per well (days)

Supply vessel

Crew boat

Tug

54.6 74.7 56.9

3.6 (1.0)b 6.0 (1.2) 3.9 (1.0)

3.2 (0.3) 2.9 (0.4) 3.1 (0.3)

0.4 (0.1) 0.5 (0.1) 0.4 (0.1)

Notes: aShallow water is defined as water depth less than 1,000 feet; deepwater is defined as water depth greater than 1,000 feet; bstandard deviations in parentheses Source: MMS DOCD plan detailed data

Number of plans with construction Number of plans with construction but without detailed data Number of plans for platform construction Number of plans for production facilities construction Number of plans for caissons construction Number of plans for satellite structure construction Number of plans for subsea wellheads/manifold construction Time to install platforms (days) Time to install caissons (days)

Source: MMS DOCD plan detailed data

181 84 81 42 71 9 33 13.1 9.3


165

Table V. Average number of days vessels are needed per well drilled and trips per week per well by water depth

Table VI. Basic information on detailed construction data

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Table VII. Average boat days needed for installation of production platforms and caissons

Table VIII. Average number of trips per week per developed structure and per well drilled needed for production

Table VII shows the number of boats needed for the installation of caissons, platforms, satellite structures, and subsea manifolds. Assuming platforms require 13 days on average to install and caissons take on average nine days to install, then about 0.7 OSVs are needed per day for platform installation and about 0.6 are needed per day for caissons. The DOCD plans did not contain information on the duration of satellite or subsea manifold construction duration and can only be analyzed on a per installation basis. Production. Unlike other stages of development, production is primarily associated with crew boat and supply boat activity. In the DOCD plans, data on the number of OSV trips are split into two or more calendar years with the total number of trips reported for each year. If the first year of data is incomplete because production is scheduled to start after the first calendar year has already begun[5], then we assumed that data from the second year was a better estimator of the number of OSV trips needed and used it in the analysis. Of the 311 plans reviewed, 192 contained information on the number of OSV trips during production. Table VIII shows the number of trips required per week during production per developed structure and per well drilled. We examined OSV needs by water depth by dividing the sample into shallow (less than 200 feet), intermediate (200 to 1,000 feet), and deepwater (greater than 1,000 feet) categories. The production needs by water depth are shown in Table IX. Table IX shows that crew boat needs are greatest at intermediate depths and that supply boat needs increase with increasing depths. This is due to the fact that helicopters are a major mode of transportation for deepwater structures. We also examined the differences in OSV needs during production by structure type. Table X shows the results of the analysis. Many of the sample sizes are small[6] making statistical analyses ambiguous. Caissons and well protectors require the fewest number of vessel trips. Although sample sizes were small, spars required the greatest number of trips in support of production. This could be due to the large

Derrick barge Tug Supply Crew OSV total (crew

þ

supply)

Platforma

Caisson

Satellite structure

Subsea manifold

9.3 (5.4)b 6.8 (5.5) 4.2 (5.9) 4.8 (5.9) 9.1 (8.8)

10.5 (12.8) 7.8 (13.6) 2.8 (4.3) 2.8 (4.1) 5.6 (7.9)

17.3 (19.9) 13.0 (22.8) 4.5 (9.0) 4.5 (3.1) 9.0 (10.4)

32.7 (52.3) 11.0 (14.9) 110.7 (171.3) 0 (0) 110.7 (171.3)

Notes: aSample size is 30 for platforms, 28 for caissons, four for satellites, and three for subsea manifolds; bstandard deviations in parentheses Source: MMS DOCD plan detailed data

Crew Supply Total

Per developed structure

Per well drilled

0.9 (1.7)a 1.8 (2.3) 2.7 (3.0)

0.6 (1.3) 1.3 (1.9) 1.9 (2.6)

Notes: Sample size ¼ 192; astandard deviation in parentheses Source: MMS DOCD plan detailed data

production volumes and personnel demands on deepwater structures which could necessitate more frequent vessel support. Pipelines. Of the 311 plans, 122 included plans for pipeline construction and 83 included detailed information on the number of service vessels needed. Table XI depicts the per installation number of days bury and lay barges, supply boats, crew boats, and other support vessels are needed. Summing the crew and supply vessel needs per day gives a value of 0.43 OSVs per day during pipeline installation. We also analyzed supply and crew boat needs per mile of pipeline installed. These data are also shown in Table XI. When the number of vessels needed is divided by the mileage of pipeline to be installed, the standard deviations increase considerably. Thus, the number of vessels needed per individual pipeline installation will probably be more informative as an estimate of OSV needs than the number of OSVs needed per mile of pipeline. Limitations of the detailed data. The detailed data reported here are biased by the fact that not every plan is required to submit data on vessel needs. MMS uses a checklist to determine if a plan is required to specify their per vessel emissions

Water depth (feet)

Crew boat

Supply vessel

Sample size

0.8 (1.6)a 1.3 (1.9) 0.8 (1.9)

1.7 (2.4) 2.0 (2.0) 2.4 (2.2)

147 30 15

, 200

200-1,000 . 1,000

Note: aStandard deviations in parentheses Source: MMS DOCD plan detailed data

Structure type Caisson Fixed Well protector Subsea manifold Spar Other (TLP, CT)

Crew boat

Supply vessel

Total OSV

Sample size

0.8 (1.8)a 1.1 (1.7) 0.0 (0.0) 0.3 (0.6) 1.8 (3.5) 0.0 (0.0)

1.5 (2.1) 2.0 (2.6) 0.2 (0.4) 2.0 (1.7) 3.5 (2.5) 2.5 (3.1)

2.3 (3.5) 3.1 (3.4) 0.2 (0.4) 1.8 (2.1) 5.2 (6.0) 2.5 (3.1)

58 79 9 3 4 4

Notes: Values are in boats per week; astandard deviations in parentheses Source: MMS DOCD plan detailed data

Per pipeline installed Average (SD) Average per week Per mile of pipeline Average (SD) Average per week

Lay barge

Support vessels

Bury barge

Crew boat

Supply boat

12.6 (17.3) 6.4

15.6 (21.0) 7.9

4.2 (7.4) 2.1

1.6 (3.9) 0.8

3.7 (7.7) 1.9

27.5 (115.3) 14.1

32.1 (122.2) 16.4

6.2 (30.3) 3.2

0.6 (1.4) 0.3

4.5 (27.5) 2.3

Source: MMS DOCD plan detailed data


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Table IX. Average number of trips per week during production (per structure installed) by boat type and water depth

Table X. Average OSV needs during production by production platform type

Table XI. Data on pipeline construction supply needs per pipeline installation and per mile of pipeline

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(recall Figure 1). If a plan answers “yes” to any of the questions on the checklist, they are required to detail their vessel activity. The most common reasons a plan must detail its vessel activities is an affirmative answer to either of the last two items. Therefore, the DOCD plan data is believed to be biased towards shallow water plans[7]. Additionally, the detailed data only reports the number of days a vessel is required to be operational in support of activities. It does not actually report the number of trips or times a vessel enters or leaves port. It is possible that OSVs may visit many lease sites in a single trip which could result in an overestimation of vessel trips, especially during production. The detailed data only includes information from DOCD plans. As a result, it includes very little information on exploratory drilling. Exploratory drilling OSV needs could differ from needs during developmental drilling, potentially biasing the data. Plan data is also thought to overestimate trips due to the conservative nature of the data. Interviews with E&P company personnel and consultants suggested that companies may input the maximum number of trips they believe they would need so that if there is a mistake they overestimate, rather than underestimate, the planned emissions. Again, this could lead to inflated trip estimates.

5. Apache data Apache’s Fourchon operations center provided activity logs for a four month period from January 2008 through April 2008. The logs recorded every time a vessel was loaded or unloaded and included the vessel name, the date and time, the rig or platform location. These logs were matched with additional data on the activities at each rig or platform and the vessel type (crewboat, utility, or supply) to create a dataset that consisted of the vessel name, date of trip, location, and activity at location. Activities involved included drilling, plugging and abandonment, and construction. 5.1 Drilling Information on the service vessels used to supply ten rigs over a four month period was analyzed. In total, OSVs made 1,403 trips to these ten rigs over the 115 days from January 1, 2008 to April 25, 2008. In many cases an OSV supplied or crewed more than one rig per trip. Thus, the ten rigs actually required 1,946 visits from OSVs, predominately crew boats: 1,465 visits by crewboats, 461 by supply vessels, and the remainder (20) by mini-supply or AHTS vessels. Table XII shows the average number of trips needed per day by both crew and supply vessels and the total number of trips for all boat types. The ratio of the standard Vessel

Table XII. Average OSV needs in trips per week during drilling, construction, and plugging and abandonment

Utility Crew Supply Mini-supply Total

Drilling

Construction

Plugging and abandonment

10.5 (3.5) 3.5 (1.4)

2.9 (2.2) 1.8 (2.5) 0.2 (0.3)

14.0 (3.5)

4.7 (2.0)

2.8 (2.8) 1.4 (2.1) 1.4 (2.1) 0.35 (1.1) 5.9 (1.4)

a

Note: aStandard deviations in parentheses Source: Apache data

deviation to the mean decreases when all boat types are combined which may reflect the fact that supply boats can fill a limited crew boat role and vice-versa; therefore, the total number of boats used in drilling operations should have less variance than the number of trips of a specific boat type.

5.2 Development In the Apache dataset, nine construction projects required 184 OSV trips, an average of 20.4 trips per project. Owing to the relatively short duration of many construction projects, we believe that the data encompassed the entirety of at least six of the nine construction projects. Owing to the high variance on a per project basis, we divided the number of trips by the duration of activity. Table XII shows the averages and standard deviations for different boats utilized. Again, the variance (as a proportion of the mean) decreases when the number of trips are totaled boat types. The majority of trips during construction are by utility boats; 117 of the 184 trips were by utility boats. A total of 57 trips were by crewboats and just 11 were by supply vessels. As in P&A operations, boats almost never visited more than one site per trip.


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5.3 Plugging and abandonment The data on plugging and abandonment included 539 trips to 13 sites. It was not clear how many, if any, of the P&A sites were both started and completed during the period covered by the data. Therefore, we converted all data into a measure of trips per day. Table XII summarizes the results. The majority of OSVs used during P&A operations are supply vessels and utility boats. Supply vessels accounted for 217 of the 539 trips (40 percent); utility boats accounted for 173 trips (32 percent). Crewboats accounted for 131 (24 percent) of trips, while mini-supply boats accounted for 18 trips (3 percent). In contrast to drilling data, crewboats were responsible for 75 percent of activity. 5.4 Circuitry Most of the data described in this paper is in terms of visits by vessels to an offshore location. However, a vessel may visit more than one offshore location each time it leaves port. In order to forecast the total number of departures from port needed to support OCS activities, it is important to have information about the average number of offshore locations a boat visits per embarkation. This is called circuitry (in industry parlance a “milk run”) and can be expressed quantitatively as the expected number of visits made per embarkation. The Apache data allowed us to determine the number of times a ship left port and the number of times it visited another GOM site without first returning to port. To Vessel AHTS Crew Mini supply Supply Utility Other/not reported

Source: Apache data

Drilling

Construction

Plugging and abandonment

1 1.6 1 1 1 1.9

1 1.1 1 1 1.03 1

1 1 1 1 1

Table XIII. Circuitry factors by activity type in Apache dataset

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estimate circuitry we added the number of times a boat left port to visit a GOM site to the number of times the same boat visited another GOM site without first returning to port, and divided by the number of times a boat left port[8]. By definition, circuit factors are greater than or equal to one. A circuit factor of one indicates a vessel dedicated to a specific activity, while a circuit factor greater than one indicates multiple stops along the way. The circuitry factors for different vessel types in the Apache data are shown in Table XIII. Notably, only crewboats made multiple stops during drilling operations, which does not seem to be representative of the OSV industry as a whole based on our interviews and related data.

5.5 Limitations The Apache data is limited by several factors. First, the data only covers a four-month period from January through April. OSVs can only be used in favorable weather and there can be seasonality in usage patterns. As a result, the data could be biased. Similarly, due to the relatively short duration of the dataset, the data could be censored by the inclusion of incomplete events. This is especially true for drilling and P&A data which take a long time to complete. As a result, we may have data for only a portion of a project and the OSV needs typically change during different portions of work flow. Furthermore, the dataset may not include information on rare but OSV intensive events that can occur over the lifetime of offshore developments, such as well workovers, repairs, or personnel evacuations. Finally, the Apache data only includes data from the Fourchon operations center. Based on conversations with Apache personnel, we believe that the majority of trips associated with the projects studied originated in Fourchon and were therefore in our data set. However, it is likely that at least some OSV trips originated from other ports and were not included in the data. 6. BP data BP provided data on GOM operations for all of 2008. The data consisted of over 68,000 records on the activities and locations of 47 boats used throughout the year. In total, BP utilized 11,766 boat days split among 24 OCS locations 20 of which were deepwater. The total number of trips into the GOM recorded is 3,075. Of the 3,075 trips, 727 are classified as being related to the continental shelf, 2,224 are described as deepwater, and 97 are related to pipeline construction. Trips by boat type are shown in Table XIV. 6.1 Circuitry The average circuitry factors by boat class are shown in Table XIV. On average, each time a boat left port it visited 1.4 sites before returning. We separated boats into those

Boat type

Table XIV. Average and total use by boat type in BP dataset

AHTS Crew Other Supply Total

Total trips

Average trips per boat per week

Proportion of total trips (%)

Average circuitry factor

76 1,682 98 1,219 3,075

1.5 4.8 0.6 1.1 2.2

2.5 54.7 3.2 39.6 100.0

1.5 1.2 1.8 1.5 1.4

Source: BP data

used for deepwater operations and those not used for deepwater operations. The circuitry factor for boats only used on the shelf was 1.13 (SD ¼ 0.20) while the circuitry factor for those used only in deepwater operations was 1.55 (SD ¼ 0.75). This suggests that there is a difference in circuitry between shallow and deepwater operations with boats used in deepwater visiting more sites per trip than those used in shallow water operations.


6.2 Trips per production unit Table XV shows the distribution of trips by end location including both trips that originated at a shorebase and those that originated at another location in the GOM. On average among the 19 producing deepwater sites, 173 visits were made in 2008 (SD ¼ 220.7). These 173 visits were associated with 116.6 trips into the GOM (SD ¼ 136.4). The number of trips is lower than the number of visits because a number of boats visited more than one site per trip. Table XVI depicts a more detailed picture of OSV operations in support of deepwater exploration and production broken out by total visits and vessel type. The sum of visits from shore and visits following movement to another GOM location is depicted. We classified 16 sites as either related to exploration and development or production. We removed three deepwater sites from consideration (Das Bump, Exploration, and Tamara) because of the limited number of OSV trips and the limited

171

Location

Left port to OCS

Intra OCS movementa

Total visits to site

Amoco Pipeline Tubular Bells Atlantis El Dorado Freedom Holstein Horn Mountain Kaskida King Kodiak Mad Dog Mardi Gras Marlin Nakika Pompano Puma Thunder Horse Will K Western Shelf

97 27 321 50 77 189 41 58 69 89 174 8 170 127 30 11 548 227 80

46 9 103 4 25 61 58 2 26 37 124 5 122 42 61 2 395 2 2

143 36 424 54 102 250 99 60 95 126 298 13 292 169 91 13 943 229 82

Eastern Shelf

647

43

690

20 3,075

8 1,188

28 4,263

None listed Total

Activity Pipeline Deepwater exploration Deepwater production Deepwater exploration Deepwater exploration Deepwater production Deepwater production Deepwater exploration Deepwater production Deepwater exploration Deepwater production Deepwater pipeline Deepwater production Deepwater production Deepwater production Deepwater exploration Deepwater production Deepwater exploration Shelf P&A, platform removal, etc. Shelf P&A, platform removal, etc.

Note: aIntra OCS movements are movements in which a ship moves from one location on the OCS to another location on the OCS without first going to port Source: BP data

Table XV. Distribution of trips by destination in BP dataset

IJESM 4,2 Exploration and drilling site Tubular Bells El Dorado Freedom 172 Kaskida Kodiak Puma Will K Exploration and drilling average Production site Atlantis Holstein Horn Mountain King Mad Dog Marlin Nakika Pompano Table XVI. Thunder Horse Deepwater trips per week Production average by stage and boat type in BP dataset Source: BP data

Total visits to site

Duration

Visits/ week

Crew visits

36 54 102 60 126 13 229

424 250 99 95 298 292 169 91 943

Supply visits

116 107 160 99 285 14 246

2.2 3.5 4.5 4.2 3.1 6.5 6.5 4.4

1.1 2.8 2.6 2.8 1.1 3.0 3.9 2.5

0.8 0.7 1.8 1.5 1.2 3.5 2.6 1.7

366 366 366 200 366 366 366 366 366

8.1 4.8 1.9 3.3 5.7 5.6 3.2 1.7 18.0 5.83

3.4 2.9 0.7 1.0 2.4 1.9 1.0 0.3 7.0 2.23

4.4 1.8 1.2 0.7 3.1 2.5 1.5 1.1 10.3 3.0

time over which these trips occurred. We determined the duration of activity at each site and the number of trips per week needed in support of exploration and development and production activities. The average OSV use for exploration and development was determined to be 4.36 (SD ¼ 1.69) trips per week and the utilization during production was 5.82 (SD ¼ 5.0) trips per week. The increased trip number during production was due in large part to the large number of trips needed to support the Thunder Horse production platform. Also notable is the much lower standard deviation during exploration and development as compared to production perhaps indicating more regular vessel requirements. Crew and supply boat needs among sites are relatively similar. During exploration and development crewboats were used slightly more than supply vessels while during production supply boats were used slightly more than crewboats.

6.3 Continental shelf data Although most of the data provided by BP was related to deepwater activities the data also included information on 727 trips into the GOM for shelf related activities and 45 intra GOM vessel movements which were classified as shelf related. The shallow water activities were heavily biased towards decommissioning. Table XVII shows the distribution of trips among ten locations. At five locations platform removal operations were being conducted, and at three locations plugging and abandonment operations were occurring. At one site a well intervention was ongoing. OSV needs during P&A were greater than OSV needs during platform removal or abandonment. On average, during P&A operations 4.6 OSVs were needed (SD ¼ 2.54) per week for an average of

Left port for OCS GI 40 platform abandonment SM 260 platform removal WD70 and WD96 platform abandonment GI 32 platform removal and site clearance Average platform removal operations SM 205 P&A GI 95A P&A WD 94G P&A Average P&A operations

Intra OCS movement

Total visits

6 8 5 4

2 1 5 0

8 9 10 4

139 373 96

2 17 10

141 390 106

Duration

Visits/ week

161 145 84 205 148.7 271 360 264 298.3

0.3 0.4 0.8 0.1 0.4 3.6 7.5 2.8 4.7

Source: BP data

298 days (SD ¼ 53.5), while during platform removal an average of 0.43 OSVs were needed per week (SD ¼ 0.29) for an average of 119 days (SD ¼ 79).

6.4 Pipeline data Only two pipeline projects were contained in the BP data, the Mardi Gras pipeline and the Amoco pipeline. The Mardi Gras pipeline included 42 days of data reports including 13 trips (an average of 2.16 per week). Notably, all but two of these trips were conducted by remotely operated underwater vehicle (ROV) boats; the other two were by crew boats. The Amoco pipeline project contained information from the entire year and required 143 trips (2.75 trips per week). In this case, 114 of the 143 trips were conducted by crew and supply vessels (74 supply trips; 40 crew boat trips). A total of 29 trips were by ROV support vessels. 6.5 Limitations The BP data provides a useful perspective due to its emphasis on deepwater activities, however, due to this emphasis care should be taken when extrapolating. Deepwater activities represent a large fraction of GOM production but a small fraction of GOM infrastructure and deepwater logistics. Furthermore, the shallow water data included in the sample is not related to production or drilling, the activities represented in the deepwater data; this makes comparisons between the data less meaningful. The BP data does not provide information on the developmental stage of the production units. Deepwater development is complex and multiple developmental stages typically overlap. For example, even though production is occurring from some wells, drilling or workovers may be occurring simultaneously. If this occurred during 2008, we would not be aware of it and would treat trips that may be in support of drilling as production. 7. C-Logistics data CL is an OSV operator in the GOM and a division of Edison Chouest, one of the region’s dominant OSV companies. CL provided data on OSV use over an 18-month period from late May 2007 to late November 2008. The data contained records of 4,788 trips conducted in support of drilling and production, vessel type, start and end shorebases, destination, tonnage, and activity.


173 Table XVII. Activities and OSV use on continental shelf locations in BP dataset

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7.1 Production Production data included information on 929 voyages conducted in support of the operations of three supermajors. The average voyage took 2.5 days and boats often visited more than one site. The distribution of trips by boat type is shown in Table XVIII. The dataset included information on fast supply boats and can be considered a type of crewboat. Average circuitry factors during production by boat type are shown in the last row of Table XVIII. Fast supply boats have a circuit factor near unity indicating they are dedicated to a specific site. Crewboats and supply boats have a larger average circuitry, indicating a greater number of intermediate destinations. Boats visited between one and six sites per trip. The total number of visits per week were determined using the duration of activity at a particular site, that is, the difference in time between the first trip and the last trip at a site and not the overall duration. A summary by water depth is shown in Table XIX. Fewer trips were conducted per week for deepwater than shallow water activity. 7.2 Drilling CL data also included information on 3,858 voyages in support of drilling. Table XIX shows the number of trips per week during drilling by water depth. Shallow water drilling required slightly fewer trips per week than deepwater drilling; this potentially due to the large storage capacity of drillships which require infrequent replenishment. The distribution of trips by boat type is shown in Table XX. Drilling support included a small proportion of AHTS trips which did not occur during production. The average duration was 3.5 days, longer than trips in support of production. However, circuitry factors were lower during drilling. The number of sites visited per trip ranged from one to four, with an average of 1.25.

Activity

Table XVIII. Number of trips by boat type and activity and circuitry factor during production

Production Drilling Total Circuitry factor

Crew

Fast supply

Lift

Supply

Utility

0 30 30

203 634 837 2.39

63 1,286 1,349 1.22

1 1 2

336 1,828 2,164 2.10

326 80 406 1.29

Source: C-Logistics data

Depth (feet) , 200

Table XIX. Number of trips per week during production and drilling by water depth in CL dataset

AHTS

200 to 1,000 . 1,000 Total

Productiona

Drillinga

2.9 1.4 1.0 1.7

4.7 3.0 3.8 3.9

Notes: Values do not include circuitry, only the number of support visits conducted; asample size ¼ 24 sites for production; 33 sites for drilling Source: C-Logistics

7.3 Limitations The CL drilling data is almost exclusively deepwater drilling which may confound drilling and production activity. The CL data was provided with flags describing whether a voyage was related to drilling or production. Several sites were included as both drilling and production. It is possible that both drilling and production occurred either simultaneously or sequentially at these sites. It is also possible that some voyages supported both drilling and production operations (due to circuitry) but were coded as only supporting one or the other. Overall, this occurred in a small proportion of the total number of voyages and are not believed to bias the results significantly.


175

8. Interview and survey data 8.1 Interview data We conducted phone interviews and electronic mail correspondence with managers of five OSV operations companies to serve as a check on the quantitative numbers discussed above. The companies these managers worked for ranged from very large to very small. According to interviewees, drilling is the most intensive period of OSV use, especially over the first several weeks a rig is on site. E&P companies usually have one crew boat and one supply boat dedicated to each drilling operation. During drilling and for most shallow water locations, supply boats make three trips per week, which is approximately the maximum number of trips a supply boat can make due to loading, unloading and travel times. For drilling projects farther offshore, operators may use two supply boats. Crew boats may make three to seven trips per week in support of drilling. Including both boat types, drilling might require six to 13 trips per week. For manned platforms respondents indicated that OSVs were needed two to three times per week. 8.2 Survey data In addition to conducting interviews with OSV operators, we also conducted surveys of several independent E&P companies. We were provided summary estimates for the number of trips over the course of a year. McMoRan. According to McMoRan’s, in 2008, they had 69 blocks in production in town areas. Vessels left from four shorebases: Intracoastal City, Fourchon, Freeport, and Venice. In general, a ship would make one trip per week to an area (for example, Eugene Island) and visit all of the blocks in that area or other nearby areas. On average, each site would be visited 1.7 times per week during production and the circuitry factor was 6.9. Drilling was more OSV intensive. Only three sites were drilled in 2008. During drilling each ship visited only one site before returning to port and on average visited seven times per week. Boat type

Trips

Percent of total

Circuitry factor

AHTS Crew Fast supply Supply Utility Total

30 634 1,286 1,828 80 3,858

0.8 16.4 33.3 47.4 2.1 100.0

1.13 1.21 1.23 1.29 1.39 1.26

Source: C-Logistics data

Table XX. Distribution of trips by boat type and circuitry factors during drilling in CL dataset

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Stone energy. Stone energy provided data from 2007 to 2008. We used data from both years for construction and drilling data. Production data was identical in both years. The shorebases used were Dulac, Freshwater City, and Fourchon. Over two years, stone drilled eight wells. The shorebase for seven of these eight wells was Fourchon, while the final well was sourced from Freshwater City. During drilling, there were 5.37 trips made per week and OSVs never visited more than one site. A totalof 43 blocks were included in production in 2008. Of these, all but one had only one site listed as a shorebase. One block had both Fourchon and Freshwater City listed as shorebases. During production, 1.9 trips were made per week and the average circuitry was 3.33. During development, 1.2 trips were made per week and the average circuitry was 2.4. 8.3 Limitations The interview and survey data is summary data and therefore less useful for developing average estimates of use by activity, however, it is useful as a check on the other data sources. Self reported data is often of highly variable quality, and for reasons described previously cannot be used for modeling activity because of its coarse nature. 9. Comparisons among data sources Comparisons of the various data sources are shown in Table XXI. The simple data predicts that the average number of trips needed per week during drilling are between 3.5 and 3.7 for crew boats and 3.2 for supply boats. The detailed data gives similar numbers of 3.9 and 3.1 trips, respectively. According to the simple data about 1.9 crew boats trips and 1.7 supply boat trips are needed per week for construction. This assumes that the construction requires more vessel activity than production and that E&P companies report the maximum vessel usage in the simple data tables in the DOCD and EP plans. The comparable numbers from the detailed data are slightly larger, but generally agreeable. Using the average construction times given in Table VII, the average number of crew boats needed per week is 2.0 for caissons and 2.5 for platforms; the values for supply vessels are 2.2 and 2.1. The simple and detailed data are not entirely independent and despite the large standard deviations in the data they agree relatively well and the concordance provides a degree of confidence in the estimates. There is general agreement between the Apache and plan data, especially in the total number of boats needed. The exception is in drilling in which the Apache data shows significantly greater OSV requirements. This discrepancy could occur if Apache uses significantly more OSVs during drilling than average or if the actual number of trips is different from the planned number of trips. Alternatively, this discrepancy could be due to the number of instances in which a single ship visited multiple drilling rigs in a single trip. In the Apache data, there were many instances in which OSVs visited multiple drilling rigs during a single trip. In our analysis of Apache data, we counted the number of times ships visited rigs rather than the number of trips. It is possible that many DOCD and EP plans report only the number of trips, rather than the number of visits. In fact, based on discussions with industry participants, we believe this is often the case. The BP data contains trip numbers that are slightly lower than the other data for drilling and slightly higher for production. This is likely due to the differences in water depth and distance to shore between the plan and Apache data and the BP data.

Activity

Data source

Drilling

Simple Detailed Apache BPb CLb Interview Stone McMoran Simple Detailed BPb CL Interview Stone McMoran Apache BP Simple Detailed Apache Stone Interview Simple Detailed BP

Production

P&A Construction

Pipeline

Crew boats a 3.5-3.7 3.1 10.4 2.4

1.9 0.8 2.4

1.3 1.9 2-2.5 1.7

Supply vessela 3.2 3.9 3.2 1.7

1.8 1.7 2.4

1.4 1.7 2.1-2.2 0.2

Totala 6.7 7.0 13.6 4.36 3.9 6-13 5.4 7 3.7 2.5 5.8 1.7 2-3 1.7 1.9 5.7 4.7 3.6 4.1-4.7 4.7 1.2

Circuit factor


1.3 1.1-1.4 1

177

1.2-2.4 3.3-6.9

1

1.0 2.4

2.5 0.9

2.4 2.2

4.9 3.1 2.5

Notes: aAll data are in trips per week; bindicates deepwater; blank values indicate estimate is not available

Interview data generally matched the plan, Apache and BP data. The interview data suggested a total of six to 13 trips per week in support of drilling. This matched the minimum and maximum averages obtained from the plan, BP and Apache data. The interview data suggested that during production manned platforms require many more trips than unmanned platforms. This was not apparent in any other data source. Despite large variances, the various data sources examined agree relatively well. Further, based on interviews with industry participants, the large variances appear to be due to actual differences in OSV use patterns rather than statistical abnormalities; that is, the variances are functions of the large variances in the underlying data rather than under-sampling. The critical issue with which there is limited agreement among data sources is the extent to which unmanned platforms are visited by OSVs during production.According to interview data, unmanned platforms are treated differently from manned platforms and are visited less frequently during production; however, this was not apparent from the plan data as there were not large discrepancies between OSV needs for caissons (which are generally unmanned) and fixed platforms (which are more likely to be manned[9]). Given the large number of unmanned platforms and their relatively long lifetimes, their treatment in models of OSV use will be critical to overall OSV estimation. No clear trend in circuitry factors emerged from the data. This was due to very large variances in the data as well as our inability to compute circuitry factors from many of the

Table XXI. Comparison of data sources for estimating OSV needs

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available data types. Circuitry factors likely vary among companies more than usage rates as circuitry factors depend on the number of operations a company has ongoing at a time, their spatial distribution and supply needs. Furthermore, large E&P companies operating in deepwater may be comparatively uninterested in relatively small economies generated by circuitry and are more likely to focus on ensuring that expensive deepwater operations do not suffer downtime because an OSV is not available. In general, circuitry factors between 1.2 and 2 appear typical for shelf operations.

10. Conclusions Throughout the offshore basins of the world, wherever oil and gas is discovered, a support industry will develop and evolve with the needs of industry and government regulation. In the US GOM, a large variety of marine vessels transport goods and provide services to exploration, development and production activity. The spatial and temporal dynamics of the logistics network is complex, dynamic and closely interrelated to the magnitude, duration, type and sequence of offshore workflows and activities. OSVs provide a vital link between offshore E&P activities and shore-based facilities. Offshore oil and gas operations cannot function without them, and their utilization and spatial distribution provide a way of understanding the impacts of the oil and gas industry on coastal communities. The data presented here provide a first attempt at quantifying the number of vessel trips required for offshore oil and gas development. The data can be used to partition OSV use among GOM shorebases, to allow for an estimation of total GOM-wide OSV use, for life-cycle analysis of offshore development, and a myriad of policy and planning applications both in the GOM and in offshore basins generally. OSVs have significant ecological impacts in terms of erosion (Bauer et al., 2002; Garel et al., 2008) and emissions (Wilson et al., 2007). The systematic study of the OSV industry in either a single basin (as in this study) or a comparative context across basins, could provide for efficiency gains in OSV utilization and consequent reductions in emissions and wake effects. New technologies, most notably AIS, have recently become available which may help in this effort (Perez et al., 2009). This study, when combined with information on the geographic distribution of vessel activity, provides the basic data for an estimation of shorebase specific OSV utilization across the US GOM, however, the methods and potentially some of the data, are applicable to other offshore basins as well. To determine the total OSV utilizationin an offshore basin, one simply multiplies the utilization factor for a given stage provided in this paper by the number of facilities in that stage, divided by the circuitry factor, then sums across all stages. For example, if seven crew and supply vessels are needed per well drilled, and 100 wells are drilled per year, a circuitry factor of 1.25 yields 165 trips per year ((7 £ 100)/1.25). Notes 1. Offshore operations occur throughout the world on all continents except antartica. Most offshore reserves are located in deep water greater than 1,000 feet. At present, the principal deepwater fields are located in the GOM, offshore Brazil, West Africa, Southeast Asia, and the North Atlantic margin. 2. The OCS is the federally regulated waters of the GOM.

3. For example, the seafloor terrain in the deepwater GOM is rougher than the relatively smooth and gradually sloping seafloor of the shelf. Hills, valleys, and ridges with unstable and hard bottoms characterize deepwater topology. 4. Based on conversations with E&P company staff and consultants responsible for submitting the plans, the number of visits by a boat to a site is generally the actual quantity input into the DOCD plan. 5. For example, a DOCD plan might require one crew boat trip per week, but report only 26 in the first year and 52 in the second year if the date of first production is expected to occur midway through the first year. 6. A number of plans did not report information on production facilities; therefore, our total sample size was 157, smaller than the data set presented in Table IX. 7. We tested the water depths associated with plans that did and did not contain vessel information using a two-tailed t -test and found a significant ( p ¼ 0.001) difference between the minimum block water depth. This indicates that the data in our sample is biased towards shallow water sites. We then conducted a regression analysis for which we had both vessel requirements during production and minimum block water depths. No relationship between water depth and vessel needs was found. Therefore, we believe our data are unlikely to be badly biased due to the relative lack of deepwater plans. 8. For example, if a boat left port ten times and made 20 intra GOM movements, then the expected number of visits made per embarkation would be (10 þ 20)/10) ¼ 3. 9. Of the 2,400 producing platforms in the GOM in 2008, about 900 were classified as manned 24 hours.

References Aas, B., Buvik, A. and Cakic, D. (2008), “Outsourcing of logistics activities in a complex supply chain: a case study from the Norwegian oil and gas industry”, International Journal of Procurement Management , Vol. 1, pp. 280-96. Aas, B., Halskau, O. and Wallace, S.W. (2009), “The role of supply vessels in offshore logistics”, Maritime Economics and Logistics , Vol. 11 No. 3, pp. 302-25. Aas, B., Gribkovskaia, I., Halskau, O. Sr and Shlopak, A. (2007), “Routing of supply vessels to petroleum installations”, International Journal of Physical Distribution & Logistics Management , Vol. 37, pp. 164-79. Ahmed, N. and Miller, H.J. (2007), “Time-space transformations of geographic space for exploring, analyzing, and visualizing transportation systems”, Journal of Transport Geography, Vol. 15, pp. 2-17. Barrett, D. (2008), “The offshore supply boat sector”, Marine and Commerce, February, pp. 36-41. Bauer, B.O., Lorang, M.S. and Sherman, D.J. (2002), “Estimating boat-wake-induced levee erosion using sediment suspension measurements”, Journal of Waterway, Port, Coastal, and Ocean Engineering , Vol. 128, p. 152. Cairns, J.A. and Harris, H.A. (1988), “Firm location and differential barriers to entry in the offshore oil supply industry”, Regional Studies , Vol. 22, pp. 499-506. Fagerholt, K. and Lindstad, H. (2000), “Optimal policies for maintaining a supply service in the Norwegian Sea”, Omega, Vol. 28, pp. 269-75. Finch, J.H. (2002), “Transferring explorationand production activities withinthe UK’s upstream oil and gas industry: a capabilities perspective”, Journal of Evolutionary Economics , Vol. 12, pp. 55-81.


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Fremont, A. (2007), “Global maritime networks: the case of Maersk”, Journal of Transport Geography, Vol. 15 No. 6, pp. 431-42. Gale, B.G. and Albright, J. (1993), “Energy facility siting in coastal zones”, Coastal Zone’93: Proceedings of the Eighth Symposium on Coastal and Ocean Management, New Orleans, LA, USA, July 19-23, pp. 29-42. Garel, E., Lo´pez Fernańdez, L. and Collins, M. (2008), “Sediment resuspension events induced by the wake wash of deep-draft vessels”, Geo-Marine Letters , Vol. 28, pp. 205-11. Gerwick, B.C. (2007), Construction of Marine and Offshore Structures , 3rd ed., CRC Press, Boca Raton, FL, p. 813. Gribkovskaia, I., Laporte, G. and Shlopak, A. (2007), “A tabu search heuristic for a routing problem arising in servicing of offshore oil and gas platforms”, Journal of the Operational Research Society, Vol. 59, pp. 1449-59. Holland, C.P., Shaw, D.R. and Kawalek, P. (2005), “BP’s multi-enterprise asset management system”, Information and Software Technology , Vol. 47, pp. 999-1007. Hull, B. (2002), “A structure for supply-chain information flows and its application to the Alaskan crude oil supply chain”, Logistics Information Management , Vol. 15, pp. 8-23. Matos, S. and Hall, J. (2007), “Integrating sustainable development in the supply chain: the case of life cycle assessment in oil and gas and agricultural biotechnology”, Journal of Operations Management , Vol. 25, pp. 1083-102. MMS (2007), Proposed Final Program: Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012 , US Department of the Interior, Minerals Management Service, Washington,DC. Parola, F. and Veenstra, A.W. (2008), “The spatial coverage of shipping lines and container terminal operators”, Journal of Transport Geography , Vol. 16 No. 4, pp. 292-9. Perez, H.M., Chang, R., Billings, R. and Kosub, T.L. (2009), “Automatic identification systems data use in marine vessel emission estimation”, paper presented at the 18th International Annual Emissions Inventory Conference, Baltimore, MD, April 17-19. Price, W. (1987), “Offshore oil and the coastal zone: a role for seaports”, Coastal Management , Vol. 15, pp. 229-45. Randle, R.V. (1981), “Coastal energy siting dilemmas”, Natural Resources Journal , Vol. 21, p. 125. Romero, M., Sheremetov, L. and Soriano, A. (2007), “A genetic algorithm for the pickup and delivery problem: an application to the helicopter offshore transportation”, in Castillo, O. (Ed.,) Theoretical Advances and Applications of Fuzzy Logic and Soft Computing , Springer, Berlin. Wilson, D., Billings, R., Oommen, R. and Chang, R. (2007), Year 2005 Gulfwide Emission Inventory Study , OCS Study MMS 2007-067, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA, p. 149.

Further reading Antonsen, S. (2009), “The relationship between culture and safety on offshore supply vessels”, Safety Science, Vol. 47, p. 1118. Bye, R. and Lamvik, G.M. (2007), “Professional culture and risk perception: coping with danger on board small fishing boats and offshore service vessels”, Reliability Engineering & System Safety , Vol. 92, pp. 1756-63. Jayawardana, J. and Hochstein, A. (2004), Supply Network for Deepwater Oil and Gas Development in the Gulf of Mexico: An Empirical Analysis of Demand for Port Services , OCS Study MMS 2004-047, Final Report: Prepared by UNO National Ports and Waterways

Institute, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA, p. 98. Snow, N. (2009), “House members revive bill to expand OCS activity”, Oil & Gas Journal , Vol. 107 No. 18. Villasenor, R., Magdaleno, M., Quintanar, A., Gallardo, J.C., Lo´pez, M.T., Jurado, R., Miranda, A., Aguilar, M., Melgarejo, L.A. and Palmeri’N, E. (2003), “An air quality emission inventory of offshore operations for the exploration and production of petroleum by the Mexican oil industry”, Atmospheric Environment , Vol. 37, pp. 3713-29.

Appendix. Minerals Management Service OSV activity estimation The Outer Continental Shelf Lands Act (OCSLA) is the key statute governing US federal offshore leasing and development. Enacted in 1953 and amended several times, the OCSLA (43 U.S.C 1331 et seq.) is the Department of Interior’s primary authority for managing leasing activity on the OCS. The OCSLA codifies federal control of the OCS, and has as its primary purpose “expeditious and orderly development (of OCS resources), subject to environmental safeguards, in a manner which is consistent with the maintenance of competition and other national needs.” The MMS is the bureau within the Department of Interior that is responsible for developing leasing plans in consultation with coastal states and other stakeholders. Section 1344 of the OCSLA requires the Department of Interior to maintain a five-year leasing program which reflects consideration of economic, social and environmental values, satisfies the National Environmental Policy Act, and considers the inputs of federal agencies, the Governors of affected states, and programs developed under the Coastal Zone Management Act. In Section 1346, the Department of Interior is directed to conduct environmental studies before and after leasing to assess the impact of oil and gas development on the human, marine, and coastal environment of affected OCS and coastal areas. As part of the Environmental Impact Statements, the MMS estimates the number of service trips that arise from shore and their socioeconomic impact. The MMS describes offshore activities in the context of scenarios for the proposed actions and for the OCS program (MMS, 2007). The OCS leasing program is two-tiered, involving five-year program planning and individual lease sale planning and execution. Each scenario is a framework of assumptions based on estimated amounts, timing, and general locations of exploration, development, and production activities. Proposed actions are the individual lease sales and are represented by a range for resource estimates, projected exploration and development activities, and impact producing factors. Proposed sales are expected to lie within the scenario ranges, and a proposed action is considered representative of the individual proposed sales in each sale area. A resource estimate is performed based upon the conditional estimates of undiscovered, unleased, conventionally recoverable oil and gas resources in the proposed lease sales areas, and estimates of the portion or percentage of these resources assumed to be leased, discovered, developed, and produced as a result of a proposed action. The projection of activities required to support the resource estimate is based on a combination of historical data, empirical relationships and correlations, published information, and expert opinion.MMS personnel estimate the amount of activity andapply durationand service vesselestimates to support theactivity as shownin TableAI. A typical activity forecast is illustrated using the 2007-2012 Western Planning Area (WPA) lease sale (MMS, 2007). MMS personnel estimate that oil and gas production from the 2007-2012 WPA lease sale will result in a total of 0.242-0.423 billion barrels of oil and 1.644-2.647 trillion cubic feet of gas. The total number of exploration and development wells to develop and produce these resources is estimated according to water depth (Table IV). Structure and pipeline installation, structure removals and workovers are presented on a cumulative basis. Using the activity factors and related assumptions, the expected number of service vessel trips to support WPA developmentis estimated to range between 94,000 and 155,000 cumulative marine vessel trips (Table AII).


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An Empirical Analysis of Offshore Service Vessel Utilization in the US Gulf of Mexico

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