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Appendix A SOLIDS CONTROL HANDBOOK Schlumberger Dowell

Solids Control Programs

January 1998 Page 1 of 10

Solids Control Programs 1 “SHAKCAP” Spreadsheet Program ...................................................................................1 1.1 Input ..............................................................................................................................2 1.1.1 Screen Data .........................................................................................................2 1.1.2 Mud Data .............................................................................................................3 1.1.3 Drilling Data .........................................................................................................3 1.2 Output............................................................................................................................3 1.3 Using Shakcap ..............................................................................................................4

2 “DEWATER” Spreadsheet Program...................................................................................5 2.1 Dewatering and Disposal Cost Section ..........................................................................5 2.1.1 Dewatering Equipment Used................................................................................6 2.1.2 Manpower Costs ..................................................................................................6 2.1.3 Per Barrel Costs...................................................................................................6 2.2 Interval Data and Analysis Section ................................................................................7 2.2.1 Input Data ............................................................................................................7 2.2.2 Output Data..........................................................................................................8

3 Summary Section..............................................................................................................10 FIGURES Fig. 1. Fig. 2. Fig. 3. Fig. 4.

SHAKCAP spreadsheet. ..............................................................................................2 Input section of the DEWATER spreadsheet................................................................5 Interval data and analysis section of the DEWATER spreadsheet. ..............................7 Summary section of the DEWATER spreadsheet. ..................................................... 10

1 “SHAKCAP” Spreadsheet Program The spreadsheet file SHAKCAP can be used to calculate the flow capacity of shale shakers for a specified screen. This spreadsheet replaces the flow curves and hand calculations published in the previous solids control handbook. The flow capacity equations contained in SHAKCAP are based on empirical relationships developed from full-scale testing of numerous linear motion shakers. This model is also available in the solids control economics program SECOP. Fig. 1 is an example of the spreadsheet.

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Appendix A SOLIDS CONTROL HANDBOOK

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There are three versions of SHAKCAP. They are: SHAKCAP.WQ1

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for Quattro Pro 3.0 or higher

SHAKCAP.WK1

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for Lotus 123 2.1 or higher

SHAKCAP.WB1

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for Quattro Pro for Windows

Fig. 1. SHAKCAP spreadsheet.

1.1 Input 1.1.1 Screen Data The new shaker screen designations are required for input to describe the screen panel. A complete listing of screen designations for the most common shale shakers is included below the INPUT/OUTPUT window in the spreadsheet. 1.

2.

Screen Name (Optional)

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typically the manufacturer's designation

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use this field to identify screen

Conductance (kd/mm)

3.

conductance value listed in the screen designation

Area (sq ft)

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4.

the usable area of the panel, listed in the designation

the number of panels required by the shaker

Deck Angle

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use 3 degrees as the default angle, lower for sticky cuttings, higher only when necessary (refer to Deck Angle discussion, Chapter 3).

1.1.2 Mud Data 6.

Mud Wt (ppg)

7.

Mud PV (cp)

8.

Mud Type (Polymer or Non-polymer)

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enter 0.6 for polymer muds (e.g., PHPA).

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enter 1.0 for all other muds.

1.1.3 Drilling Data 9.

ROP (ft/hr)

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estimated average ROP for the interval

10. Hole Diam (in)

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bit diameter is normally sufficient

11. Flow Rate (gpm)

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total circulating rate

1.2 Output 1.

2

Usable Screen Area, (ft )

2.

2/3 of the total available screening area

Drl. Solids Generated, (gpm)

3.

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Number of Panels

5.

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rate at which solids will be returned

Solids Loading Factor, (%)

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the percent drilled solids in the mud

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4.

Flow Capacity-Fluid Only, (gpm)

5.

the estimated flow capacity of one shaker without solids

Flow Capacity-With Solids, (gpm)

6.

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the estimated flow capacity of one shaker with the effect of solids loading taken into account

No. of Shakers Required

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the total number of shakers required to process the entire flow rate using the specified screens

1.3 Using Shakcap 1.

The flow capacities are calculated for single deck shakers. Adjustment for tandem deck shakers or cascading systems can be made by reducing ROP by 25-50% to account for the solids removed by the scalping deck.

2.

Acceleration is assumed to be constant for all shaker types. This model assumes 3.0 g's normal to the screen. This may cause some discrepancies between actual and predicted flow capacities for shakers with significantly different accelerations.

3.

To estimate the screen size required for a given number of shakers, the following procedure is recommended:

4.

A.

Enter all input data except screen name. Choose a screen series from the supplied designation tables and use an area value common to that series. For example, all screens in Derrick's PWP 2 HP series have an area of 5.3 ft .

B.

Enter some starting value for conductance as a “first guess”.

C.

Adjust the conductance value in the input column until the number of shakers required matches the actual number available.

D.

Decrease the conductance in 0.2 or smaller increments until the “Flow Capacity-With Solids” output closely matches the anticipated circulation rate per shaker.

E.

Find the screen in the series with a conductance that most closely matches the required conductance. Enter that screen's name and conductance into the input table. Check that the number of shakers is correct.

The flow capacity for polymer muds, such as PHPA, is impossible to predict with any certainty. The spreadsheet uses 0.6 as an “average” flow capacity reduction factor. Actual throughput will depend heavily upon the concentration of the polymer and the amount of shear imparted.

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2 “DEWATER” Spreadsheet Program This spreadsheet was developed to help assess the economics of using a chemically-enhanced dewatering unit to reduce liquid discharge volumes. Dilution volumes, liquid and sludge discharge volumes are predicted for up to 4 drilling intervals with and without the dewatering option. The total costs of each case are compared to determine the most economical option. The output also can be used to estimate reserve pit or cuttings haul-off requirements. Computations are based on the mass balance equations presented in the economics chapter of the Solids Control Handbook and will not be repeated here. The spreadsheet is provided in two formats: Lotus .wk1 and Quattro Pro .wq1. The spreadsheet is divided into 3 sections: Dewatering and disposal cost input (Fig. 2), interval data (Fig. 3), and cost analysis summary (Fig. 4). Required input cells are highlighted or shaded, depending on the spreadsheet software. Scroll down through the spreadsheet to view the sections.

2.1 Dewatering and Disposal Cost Section

Fig. 2. Input section of the DEWATER spreadsheet. Cells A1.G22 contain the input data required for the dewatering economics calculations.

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2.1.1 Dewatering Equipment Used Input the number and unit cost for the listed equipment. These costs can be obtained from a service company in your area. The spreadsheet uses only the total equipment cost in the calculations; individual entries do not have to be precise, provided the total equipment cost is correct.

2.1.2 Manpower Costs ENGINEER, TECH Enter the estimated daily cost for each service engineer or technician. The number of personnel required will be made as a separate entry for each interval, since the number of service personnel will often depend on the average daily processing rate.

2.1.3 Per Barrel Costs VALUE OF RECOVERED LIQUID This is applicable when the liquid phase recovered from the dewatering unit can be used to defray the cost of the dilution mud. For example, if the base fluid is a brine costing $2/bbl, the cost of dilution will be reduced by $2 for each barrel of liquid recovered by the dewatering unit. If the liquid is to be treated and discharged, or if the recovered liquid has little value, enter a “0” in this cell. LIQUID, SOLID DISPOSAL COSTS Input the estimated cost per bbl for disposal of liquids and solids. The disposal costs should include any applicable charges for pit construction, liquid or cuttings haul-off, spreading, and remedial treatment to reclaim the site. Offshore site charges include cuttings box rental, transportation and material disposal. DEWATERING COST Chemical dewatering cost will depend primarily on the mud and solids type presented to the dewatering unit. Low solids non-dispersed muds may cost as little as $1/bbl to treat. Heavily dispersed mud systems and fine, reactive solids can push chemical treatment costs to near $10/bbl. Refer to the Dewatering chapter for more information regarding dewatering chemical costs. When possible, have the service company pilot test a sample of the mud to provide an estimate of chemical treatment cost to flocculate. Further chemical treatment, such as pH adjustment, may be necessary to reuse the recovered liquid in the mud system. This cost should also be included in the chemical treatment cost.

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2.2 Interval Data and Analysis Section Four intervals are provided in the spreadsheet. Each interval will require an estimate of drilling time, section length and hole size, existing solids control efficiency, low gravity solids content and initial circulating volume. The spreadsheet will calculate the predicted dilution and disposal volumes for the interval, and provide an analysis of dewatering costs per barrel and interval dewatering cost.

Fig. 3. Interval data and analysis section of the DEWATER spreadsheet. (1 of 4 intervals)

2.2.1 Input Data DRILLING DAYS Input the number of rotating days anticipated for this interval. START/STOP DEPTH, ft Enter the beginning and ending depth of the interval. BIT SIZE, in. Enter the bit size for the interval.

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WASHOUT,% This is the estimated average volume % washout. This less than 10% for hard, consolidated formations. Highly dispersive or unconsolidated formation may wash out as much as 50%. INITIAL CIRCULATING VOLUME, bbls Enter the estimated volume in the surface pits and downhole at the beginning of the interval. INITIAL/ENDING LGS, % For the purposes of this spreadsheet, LGS pertains to the drilled solids content. If the mud is new, enter 0 as the initial drill solids content. The ending LGS should be the maximum percent drilled solids to be tolerated in the mud. EQUIPMENT EFFICIENCY, % Enter the estimated efficiency of the active system solids control system. This value can be determined by running the solids control equipment performance and economics program, SECOP. Usually, this figure will range from 30% for poor solids control systems and fine drilled solids to 75% for excellent solids control and coarse drilled solids.

2.2.2 Output Data SOLIDS GENERATED, bbls This is the total volume of drilled solids generated in the specified interval. SOLIDS REMAINING, bbls The solids left in the mud after processing by the solids removal equipment. DILUTION REQUIRED, bbls This is the dilution volume required to reduce the mud system to the maximum specified LGS content at the efficiency specified for the solids removal equipment. MUD VOLUME TO TREAT, bbls This is the volume of whole mud which must be dumped to accommodate the required dilution volume. EQUIPMENT SLUDGE, bbls The volume of wet solids discharged by the solids removal equipment, assuming a 1:1 ratio of liquid to solids. This program does not account for weight material which may be discharged by the equipment. In weighted mud applications, the actual equipment sludge volume may be higher.

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DEWATERING SLUDGE, bbls The volume of wet solids discharged by the dewatering equipment, assuming a 1:1 volume ratio of liquid to solids. TOTAL SLUDGE, bbls The total sludge volume is the sum of the equipment sludge and the dewatering sludge volumes. LIQUID SAVED, bbls This the estimated total volume of liquid recovered by the dewatering unit. DEWATERING RATE, bbl/day This is the average volume which must be treated daily to accommodate the required dilution volume. DEWATERING COST, $/bbl This is the average cost per barrel to treat the expected volume of whole mud discharged, based on the dewatering chemical cost and the daily equipment and manpower costs. INTERVAL COST w/ DEWATERING, $ This is the total waste disposal and dewatering cost less the value of the recovered fluid. SAVINGS (LOSSES), $ The interval cost with dewatering is subtracted from the total disposal cost without dewatering. Positive values indicate savings, or the reduction in cost attributable to dewatering, for this interval.

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3 Summary Section The summary section begins at line 100. This section of the spreadsheet provides cumulative cost data on interval savings or losses and total liquid and sludge discharge volumes. At the bottom of this section, a recommendation is displayed regarding the deployment of a dewatering unit based on the economics of each interval. Savings of less than $1000 for an interval are considered uneconomic.

Fig. 4. Summary section of the DEWATER spreadsheet.

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APP_A

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