SUBSEA WELL INTERVENTION TECHNOLOGY
Submitted by:
YOHANEST CHANDRA (A0065919R)
OT5301 MECHANICAL ENGINEERING OIL & GAS TECHNOLOGY DEPARTMENT OF MECHANICAL ENGINEERING
NATIONAL UNVERSITY OF SINGAPORE February 2010
INTRODUCTION Over the past few decades, the world has realized of its dependence on petroleum. It has significant contribution in human daily activities. Mainly, the majority of world's unexplored oil wealth lies largely offshore.
Realizing the direction of oil & gas
technology, many industries have extended its early exploration and production operations with land-based rigs to exploration of the earth covered by ocean. It was faced with the deepwater challenges of what is called the "last frontiers" on this planet (the sea).
Nowadays, oil & gas industry has changed their main focus of development from onshore to offshore. This evolution from land to sea has occurred over the past century. Offshore technology applications which have been developed are; offshore platforms, semisubmersible and jackup drilling rigs, and dynamically positioned drill- ships, FSO, FPSO and FDPSO. Offshore technologies advanced to conquer increasingly hostile and challenging environments. From one point on a fixed platform or floating rig, wells could be drilled in multiple directions to reach more of the reservoir. The latest development of subsea technology has reach 3,000 m depth from the sea surface. Developing this subsea prospects in water depths up to 3,000 m really required outstanding engineering skills, equipment qualification and extreme focus on reliability.
The world markets for the subsea industry was also changing, the need to operate in developing countries like in West of Africa was essential for long-term success in the subsea oil and gas business. Many successful subsea industires were forced to relocate their share of the billions of US$ being invested in subsea projects every year. The urgency to improve and increase the productivity of the Oil well productions drive many industries to develop new technology to meet this need and subsea well intervention is one of its development as the technology is moving towards to offshore.
TABLE OF CONTENT
INTRODUCTION
I.
SUBSEA WELL INTERVENTION TECHNOLOGY
……………
1
1. WELL INTERVENTION ……………………….………………...
1
A. WIRELINE OPERATION ………………….………………….
5
B. COILED TUBING OPERATION ….………………………….
7
C. HYDRAULIC SNUBBING UNITS ……………………………
8
2. SUBSEA WELL INTERVENTION .……………………………..
10
A. TYPE OF SUBSEA WELL INTERVENTION .………………
12
I.
LIGHT SUBSEA WELL INTERVENTION …………… 12
II.
MEDIUM SUBSEA WELL INTERVENTION …………
13
III.
HEAVY SUBSEA WELL INTERVENTION …………..
14
3. SUBSEA WELL INTERVENTION IN THE MARKET ………… 15 4. FUTURE DEVELOPMENT ………………………………………. 21
CONCLUSION
REFERENCE
CHAPTER II SUBSEA WELL INTERVENTION TECHNOLOGY 1. WELL INTERVENTION A well intervention is also known a 'well work'. It is defined as any operation carried out on a oil or gas well during, or at the end of its productive life, that alters the state of the well and or well geometry, provides well diagnostics or manages the production of the well.[1] This well intervention is carried out to maintain, improve production levels, repair of wellbore mechanical failures or to suspend production. There are a lot of problems that are found during the operation of Oil well. These problems cause the productivity of the oil well to decrease and it drives the industry to develop a new technology to overcome the problems. Here are some potential problems that are found in oil well operation: •
Low Reservoir Pressure The reduction in reservoir pressure and flowrate is particularly acute in dissolved gas drive reservoirs. In gas cap and water drive reservoirs, pressure maintenance techniques can often offset the reduction in pressure due to depletion. This problem can be solved by recomplete the well with either smaller tubing or some form of artificial lift and injection
•
Wellbore Restrictions Typical causes of restrictions include scale, sand, paraffin and asphalt etc. Many of these problems may not be apparent during early field life but can become a significant problem as the field matures. A number of techniques, both mechanical and chemical are applied to remove the restriction. However, consideration should always be given to the prevention of the problems as these techniques are remedial.
•
Primary Cement Failures A poor primary cement job which leaves channels behind the casing can lead to the influx of unwanted fluids and in certain instances casing collapse. Squezee cementing has to be done to solve this issue.
•
Loss control of water and gas production
Losing control of the water and gas production can cause loss of productivity. A mechanism to control it is needed to re control the water and gas production •
Mechanical Failures Mechanical failures of tubing, casing and downhole equipment are often happened. It requires a workover to rectify the problem. These typical problems would include: casing leaks, tubing failures, packer failures and downhole safety valve failures.
Well intervention has its main objective to improve or increase the productivity of the oil wells. It is estimated that with subsea wells intervention could enhance oil well productivity by at least more than 25%. This enormous enhancement of the oil well productivity of course can’t be achieved easily. Well intervention technology has to face many challenges to obtain its objectives. The main challenge that has to be faced is lack of commonality of Christmas trees which were used in subsea operation. Each and every Oil well may have different design of Christmas tree. It makes many industries find difficulties and have to adjust or modify their well intervention application to fit each of oil well operations. There are a lot of well intervention services that has been done such as: Logging, light reperforating, plug setting/removal, flowline intervention, well commissioning, well abandonment, down-hole pump change out, scale cleanout, down-hole valve retrieval, casing leak repairs, re-drill, etc [lect notes]. Perforating and fishing will be discussed in detail in below section.
Perforating Perforating is an operation whereby holes are made though the production casing ans its cement sheath into the reservoir to permit oil or gas to flow into the wellbore. Nowadays, bullets perforator is the most common perforator that being used. Preforation must provide a clean flow channel between the producing formation and the wellbore with minimum damage to the producing formation. There are three basic perforating guns type: Retrievable hollow carrier gun, Non retrievable or expendable gun and Semi-expendable gun. These types of perforating guns can be used through three standard methods:
•
Casing gun perforating – It is run on the wireline operation
•
Through Tubing Perforating (TTP) – It is run on wireline operation
•
Through Conveyed Perforating (TCP) – It is run on coiled tubing operation
Figure 1: Methods of perforating system
TCP is the most used perforating technique because it combines the best features of both casing gun and through tubing gun. TCP method has some of advantages: •
It can perform a large interval perforating in one time
•
It is easy to perforate in deviated well
•
Large gun can be used with high shot density
•
It can be carried out in unbalanced condition
•
It is the safest method until now.
Despite of its advantages, TCP has some disadvantages if it fails to be perforated. It will need to pull out the entire system and and additional hole must be drilled below the reservoir to accommodate the gun. The perforating gun is run as integral part of the drill system test or a completion string. It will be only fired after a packer has been set, a surface tree has been installed and the entire completion string pressure integrity has been tested. Firing can be achieved using mechanical system or electrical system. Annulus or tubing
pressure is used for mechanical system. One of the examples of mechanical perforating system is Hydraulic Time Delay Perforating.
Figure 2: Mechanism of Hydraulic Time Delay Perforating
Fishing Fish is an object that is left in the wellbore during drilling or workover operations and that must be recovered before work can proceed. [2]. It can be anything from a piece of scrap metal, pipe, wireline to a part of the drill stem. Fishing is defined as any action taken which attempts to remove a fish from borehole. Fishing tools are designed to engage with items that were not originally designed to be engaged. It will be specially designed to accommodate the type of action that needs to be taken. This fishing tool is connected to the wireline operation to recover equipment lost in a well. There a lot of types of fishing tools are available in the market.
There two release mechanism for fishing. They are mechanical release system and hydraulic release system. Most of the operators prefer to use hydraulic release
system. Despite of the preference, the mechanical release system has advantages over the hydraulic system where in gas wells, which do not support a fluid column, or in case the introduction of water to the formation has to be minimized. Some of fishing tools example are:
Figure 3: Mechanical Release system (left) and Hydraulic Release system
The most common techniques utilized to perform well intervention services are wireline operation, coiled tubing operation and hydraulic snubbing unit.
A. WIRELINE OPERATION Wireline operation is defined as any techniques used to operate in producing and injecting well by means of a steel cable, to enter, run, set and retrieve measurement tools and instruments need for production [3]. A lot of services can be performed using wireline operations: logging, light re-perforating, zone isolation, plug setting/removal. Wireline operation is being done using slickline, Braided line or electric line. Slickline is a solid single strand of wire. The commonest size being used is 0.108 in. Braided line consists of stranded wires resulting in higher load capacity than slickline. It usually used to perform fishing when slickline is not sufficient to take the load. Electric line consists of stranded wire and a conductor which capable to transmit an electric signal to the surface or vice versa. Electric line is used where
electronic application is being utilized in well intervention service such as: cased-hole formation evaluation, production logging, re-preforating, setting bridge plugs and packers, etc. Wireline units are installed on offshore platforms are typically skid mounted. The wireline is spooled on to a reel that is usually hydraulically driven. To perform wireline operation, in minimum it requires : wireline, wireline winch unit, lubricator, measuring device, hay pulley, wireline clamp, stuffing box, weight indicator and Blowout preventer (BOP).
Figure 4: Open Water Wire Slick line Operation
Wireline operation utilizes many tools which can be categorized into several types. They are: •
Checking and Maintenance Tools The tools are screwed directly on the bottom of the wire line. It is used for checking and cleaning of tubing inside the well. Examples of this tool are swaging tools, sand bailers, scratchers and gage cutters.
•
Running and Pulling Tools that has been specially designed for pulling or retrieving downhole tools
•
Fishing Tools Fishing tool is used to remove any undesirable items from the borehole.
Despite of many well intervention services that can be done using wireline operation, it has some limitation limitation: •
It is risky to be operated in highly deviated wells
•
It requires highly skilled personal to operate
•
No rotation and circulation are possible for this operation and can only work in tension and moderate loads.
In overall, wireline operation has the advantages: •
The operation can be done inside the tubing without killing the well.
•
Due to light weight and its mobility, the operation can be performed fast.
•
No damage to the pay zone during the operation
•
Relatively easy to handle
•
Not really expensive in cost and many operators are available in the market
B. COILED TUBING OPERATION Coiled tubing operation serves for bigger size and bigger load than the wire line. It requires heavier equipments compare to wire line operation. In the application, usually coiled tubing operation is the operation before wireline operation. It is always carried out together with wireline operation. This unit operation is usually carried out for Nitrogen lifting, sand lifting, circulating fluid, fishing, cleaning out the well bore utilizing a downhole motor.
Figure 5: Example of Coiled tubing technique
C. HYDRAULIC SNUBBING UNITS Snubbing is also known as hydraulic workover. The principle is that pipe can be inserted or withdrawn from a well under pressure. The process utilizes jointed tubing or drill pipe with a hydraulic snubbing unit to run the tubing string without killing the well, and allows small diameter tubing to be run through the completion. Snubbing unit is heavy equipment and consists of hydraulic jack assembly, guide tube, window, travelling and stationary slips, rotary table and power tongs, work basket for control panel, hydraulic power pack, circulating swivel, kelly hose, pumps and BOP stack Snubbing unit should be able to perform three basic functions: •
Feed the pipe into and out of the well in a controlled manner against wellhead pressure.
•
Provide a seal which maintains integrity while at the same time allowing the pipe to be inserted or removed from the well.
•
Provide a means of plugging the inside of the pipe.
Snubbing unit can be used to perform: fishing, milling in casing, cleaning out cemented solids in the tubing/liner/casing, pressure control/well
killing, drilling out bridge plugs, washover, circulating out heavy fluids, acidizing, squeeze cementing. Hydraulic workover units have several advantages: •
It has greater capability than coiled tubing; it can handle relatively large tools.
•
It can be performed under pressure and in certain cases with the well still flowing.
•
Mobilisation and demobilisation are shorter reducing the overall time a well is off production.
•
The ability to rotate the pipe enables light drilling and milling work to be performed.
Figure 6: Snubbing Unit
2. SUBSEA WELL INTERVENTION Oil and Gas technology has been moving toward an offshore. Economic is the main driver for this evolution. The growth of subsea technology can be seen in figure below.
Figure 7: Growth of Subsea Technology
Subsea operation has been under performed by 25% compare to onshore operation because of well intervention [4]. This shortfall in productivity equates to $20.7 million. Hence, subsea well intervention is being developed to answer this challenge. Subsea well intervention is just simply well intervention technologies that being carried out offshore. Subsea well intervention is relatively new technology and the cost of operation is very high, but it has been predicted will regard promising market in future. Subsea well intervention requires much advanced planning as it offers up many challenges. Subsea well intervention is typically assisted with a vessel and sometimes also requires ROV (Remote Operation Vehicle) to perform its services such as production logging, stimulation, SCSSV change out, re-perforation, leak tubing repairs, fishing, well suspension, etc.
Figure 8: Below is the statistic of subsea well intervention has been carried out till 2006
Many industries have been trying to become a pioneer in the implementation of subsea well intervention. •
Shell and Oceaneering International have claimed that they have set a new industry record in subsea well intervention by replacing a failed subsurfacecontrolled subsurface safety valve in the Gulf of Mexico using an open water wireline technique at a water depth of 2,673 ft (815 m) [5].
•
ATP Oil & Gas and Blue Ocean Technologies also have claimed that they have set multiple new industry records in subsea well intervention in 2950 ft of water without a riser. Blue Ocean Technologies' Interchangeable Riserless Intervention System (IRIS) successfully completed numerous riserless wireline runs, deploying a variety of intervention tools, including a wireline tractor, gauges, milling tools, perforating guns, and a logging tool multiple times, each run of which represents a new industry record for riserless intervention. This is the first time that wireline has been successfully run in open water at 2950-ft depth. [6]
A. TYPES OF SUBSEA WELL INTERVENTION Based on the types of vessel which accommodate the well intervention operation, it classified into three major classifications: Light, Medium and Heavy subsea well intervention.
Figure 9: Types of Subsea Well Intervention
I. LIGHT SUBSEA WELL INTERVENTION Light subsea well intervention is a subsea well intervention which required only small vessel as its marine support vessel. The operation that able to be performed is a wire line operation. Light subsea well intervention can performed service limited to logging, light perforating, zone isolation plug setting and plug removal. Light subsea well intervention operation is usually carried out in 9 days/ well job and costs around $150K to $200K/day of operation [4]
Figure 10: Light subsea well intervention
II. MEDIUM SUBSEA WELL INTERVENTION Medium subsea well intervention is defined as any operation in a subsea wellbore that does not need a drilling rig to gain access to the well to convey the service or to carry out the operation [7]. Medium subsea well intervention is actually almost similar to light subsea well intervention. The difference is that medium subsea well intervention employs coiled tubing together with wireline operation. Hence, heavier task can be carried out. Medium subsea well intervention can perform flowline intervention, well commissioning, perforating, well abandonment, downhole pump change out, squeeze, acidizing , water shut-off, scrapping, valve retrieval, casing repair, etc. Medium subsea well intervention has wide scope of service but it still has its limitation which it only can perform operation which not required any drilling rig. This type of operation will require heavy subsea well intervention. Medium subsea well intervention operation is usually carried out in 9 days/ well job and costs around $150K to $300K/day of operation [4].
Figure 11: Medium subsea well intervention
III. HEAVY SUBSEA WELL INTERVENTION As it shows from the name, heavy subsea well intervention will involve a lot of heavy equipment such as drilling rig with all heavy equipment on top of it. Multiple service companies can be rigged up and working from this stable platform. A lot of heavy services can be performed by heavy subsea well intervention such as: scale milling, completion of change out or repair, re-drill, sidetrack and Christmas tree change-out. Heavy subsea well intervention operation is usually carried out in 9 days/ well job and costs around $360K to $840K/day of operation [4].
Figure 12: Heavy subsea well intervention
3. SUBSEA WELL INTERVENTION SERVICES IN THE MARKET There a lot of subsea well intervention product in the market. The latest developments are Risereless Light Well Intervention and Rigless Well Intervention.
RLWI technology was developed in demand of maintaining subsea wells as it can improve recovery rates and reducing the cost of maintenance. Dynamically positioned (DP) vessel are used in RLWI to improve the performance of maintenance and it can be performed more efficient and at lower cost. [8]
Figure 13: Riserless Light Well Intervention
Detail of Rigless Well intervention will be discussed below.
RIGLESS SUBSEA WELL INTERVENTION Rigless subsea intervention system has optimized the capability of two complementary subsea intervention operation: Wireline Operation and the Coiled Tubing Operation [9]. It enables rigless coiled tubing, electric line and slickline thru-tuibing services in subsea wells in water depths of up to 3,000m. The system consists of the subsea Well Intervention Package (WIP), Intervention Package Control System (IPCS), umbilical, well servicing equipment, marine support, vessel, handling and deployment equipment, and ROVs. Subsea Well Intervention Package This product from Schlumberger is designed to 10,000 psi and 7 3/8-in ID size to allow retrieval of larger horizontal tree. The WIP can be operated using wireline operation or coiled tubing operation [9]. It consists of three main components: 1. The Lower Intervention Package (LIP) The LIP has its job to provide a connection of the Well Intervention Package onto the subsea tree and to provide the required static, redundant well control barriers
2. The Lubricator Package (LUB) The lubricator is 7 3/8-in ID in size and has its function to allow the insertion of toolstrings into the well. 3. The Upper Intervention Package (UIP) The UIP provides the dynamic sealing function required during inhole operations under pressure as well as the capability to safely disconnect in case of vessel positioning or other emergency problem. This package is designed to be deployed in a single run for efficient deployment in deepwater, whenever adequate handling and lifting facilities are provided on the support vessel. This UIP package is the one that make the difference between rigless wireline operation and rigless coiled tubing operation. In coiled tubing operation, UIP package incorporates a subsea dynamic seal. This seal is the well control barrier and features a dual redundant sealing element package that deployed and retrieved with tool string on every run. Whereas, UIP package in wireline operation is based on existing stuffing box technology to seal against slickline. A polymer embedded cable has been incorporated so that can be used as if it is slickline for sealing purposes. UIP wireline operation package has the advantages over the UIP coiled tubing operation package. Its cable is combined with the seal and eliminates grease injection for operation.
Figure 14: Main component of Well Intervention Package
Intervention Package Control System (IPCS) IPCS is the main controller of the rigless well intervention. It has main functions of the control system to: •
remotely actuate the WIP and a configurable array of subsea Christmas tree functions from the vessel
•
enable a subset of WIP and subsea tree functions using the ROV
•
acquire various WIP data in real time for transmission and display at surface
•
automatically or manually initiate a sequence of WIP functions in case of emergency
The control system architecture of IPCS is common for both wireline operation and coiled tubing operation. The control system is based on a distributed system architecture where independent valve modules are installed at various locations on the WIP. Electronics control is installed near the valves which are to be operated in identical fashion as the control systems used on most modern work-class ROVs. The control system also provides power and controls to a dual redundant subsea WIP Pumping System which mounted on the LIP to provide
the required pressure testing, lubricator flushing and hydrate prevention / remediation functions. Umbilical The umbilical is comprised of two separate power and communication bundles, one for each multiplexed telemetry system (operating and stand-by). Launch and Recovery System (LARS) is used on the side of the vessel to deploy the umbilical for ease and can be actively positioned from surface to facilitate down-line management. Well Servicing Equipment Standard slickline, electric line, and coiled tubing equipment packages can be used with this system. Some synergies are gained through cross training of personnel and co-location of power and control features. Marine Support Marine support is a vessel which assists the WIP operation. The WIP package can not be deployed anytime we want it. It will depend on the nature condition such as wave height and current of the sea. It is the reason marine support is needed. Based on the size of equipment and also operation, marine support vessel has some requirement: •
100 to 120m length by 20 to 25 m breadth
•
Minimum 1,000 m² deck space, excluding ROV requirements. Some equipment such as pumping units and liquid storage tanks will be integrated into the hull of the vessel
•
Dynamic position level 2
•
Living quarters for minimum +/-95 personnel
•
Two 150 hp Work Class ROVs
•
7m x 7m moonpool
•
Handling tower or mast with AHC deep water winch or AHC deep water crane
It should be noted that for wireline service has smaller deck space requirements, the vessel could theoretically be smaller Handling and Deployment Equipment The handling system consists of the following main components:
•
Tower to support the well intervention package components as they are prepared to be run into the water column and through the splash zone. This includes a cursor system to guide components through the splash zone and means of opening / closing the moonpool.
•
Deployment Winch to lower and retrieve the well intervention package components to and from the seabed
•
Hang-off system for the support of the well intervention package components at the level of the moonpool door
•
Skidding System to move equipments on the support vessel from parking positions to working and/or deployment positions
•
Umbilical Handling to launch and recover the control system umbilical.
•
Tensioner to deploy the coiled tubing through the water column
ROVs Two ROVs are required for redundancy. The ROVs are work-class ROV’s with a power of about 150 hp and rated for a maximum water depth of 3,000 m On the objective to bring the Rigless subsea intervention services to 3000m, some challenges are found. These challenges are: •
No Guideline Guideline-less deployment is only relying on the ROV and marine vessel support for positioning and guiding the package on to the subsea tree. The lack of guidelines calls for an active heave compensation system. Two such AHC systems for electric line logging are currently being trialed.
•
Umbilical Size Bigger size of umbilical has bigger diameter of umbilical cores. It will lead to friction losses versus water depth reach its practical limits of non-metallic hose technology. When the size is bigger, he weight of umbilical is also become bigger and it will come to the hydraulic umbilical become impractical. Of course placement of Hydraulic power unit and pumping system subsea can eliminate this issue, but it would be expensive.
•
Hydrate at dynamic seal
There is a potential of hydrate formation in dynamic seals made from polymer encapsulated cable (marinzed version) when the gas enter the column •
Economic availability Rigless subsea intervention is as much of a commercial exercise as it is a technical one. If the rigless intervention system does not result in a significant reduction in intervention cost then interventions will either not be performed or will be done using a rig as the basis for
The combination of OWWL and SCG methodologies in a single system provides a complete and robust LWI solution for rigless subsea intervention in deepwater. The system excludes welltest operations, but enables coiled tubing, electric line and slickline operations, and can complete greater than 80% of the anticipated interventions that do not entail pulling the completion. The ability to select slickline, electric line and/or coiled tubing conveyance at will creates a service that as a whole is greater than the sum of its parts and will be universally applicable. The cost of intervention is projected to be less than of that when performing the same intervention with a drilling rig. Multiple conveyance offerings maximize the chance to successfully complete an intervention by increasing the possibility to use a variety of tools. A wellbore maintained subsea results in an acceptable Tolerance of Risk and allows the use of a cost effective construction vessel to support coiled tubing operations rather than a drilling rig or large MODU class vessel [9].
4. FUTURE DEVELOPMENT Subsea well intervention technology is considered a new technology in oil and gas industry. With the driver to move toward offshore technology, it is predicted that new subsea technology will be improved and may be new invention will arise. Some industry players have begun to develop various breakthrough and advancement to optimize the performance of subsea technology. This improvement is moving toward an effective and efficient subsea well intervention.
CONCLUSSION Subsea well intervention basically is not much different with onshore well intervention. Almost all well intervention service that can be done in onshore now can be done in offshore because of this subsea well intervention technology. The oil and gas industry demand which want to move the technology towards offshore is the main driver for subsea well intervention. Many types of subsea well intervention can be chosen with regards of techniques and type of vessels support. Base on the techniques, the main of subsea well intervention can be classified into: Wireline Operation, Coiled Tubing Operation, and Hydraulic Snubing Operation for heavy duty. Subsea well intervention also can be classified into Light Subsea Well Intervention, Medium Subsea Well Intervention and Heavy Subsea Well Intervention. Subsea well intervention has increased the productivity of the subsea well by around 25%. It has answered the challenged for the improvement of the subsea well but still al ot of challenge are waiting out there. Subsea well intervention is relatively new technology and the cost of operation is very high, but it has been predicted will regard promising market in future. Subsea well intervention requires much advanced planning as it offers up many challenges. It is predicted that new subsea technology will be developed. More effective and efficient of subsea well technology will be invented. It is now our call to try and give our best toward this subsea technology
REFERENCES [1]
http://en.wikipedia.org/wiki/Well_intervention
[2] http://www.osha.gov/SLTC/etools/oilandgas/glossary_of_terms/glossary_of_term s_f.html [3]
Abalt Solution Limited, Well Intervention and Workovers, 2005
[4]
Schlumberger, Subsea Well Intervention, 2006
[5]
http://www.offshore-mag.com/index/articledisplay/9023750908/articles/offshore/subsea/us-gulf-of-mexico/2009/12/shell_oceaneering.html
[6] http://www.worldoil.com/Blue_Ocean_ATP_set_subsea_well_intervention_recor ds.html [7]
Deepstar report, 2002
[8]
http://aberdeen.spe.org/images/aberdeen/setup%20Jensen,%20StaoilHydro.pdf
[9]
Bill Sierdorfer, Rigless Subsea Intervention: A Nove System Enabling Deepwater Coiled Tubing, Electric Line, and Slickline Operations
OTHER REFERENCES OT5301 Subsea Systems Engineering Lecture Notes. 2010 http://www.weatherford.com http://www.slb.com http://www.fmcthecnologies.com http://www. spe.org
