SOLIDS CONTROL HANDBOOK Schlumberger Dowell
Solids Control Equipment Discharge Analysis, Oil Based Muds
Appendix C January 1998 Page 1 of 7
Solids Control Equipment Discharge Analysis, Oil-Based Muds 1 Introduction .........................................................................................................................1
2 Sample Collection...............................................................................................................1
3 Retort Procedure.................................................................................................................2
4 Alternate Retort Procedure for Air-Entrained Cuttings Samples .....................................2
5 Solids Analysis Calculations..............................................................................................3
6 Example Calculations .........................................................................................................5
7 Calculations.........................................................................................................................6
1 Introduction Analysis of the solids control equipment discharge provides valuable information about equipment performance and identifies the composition and rate of the discharge stream. These calculations are designed for oil-based muds, but can be used for water-based fluids as well.
2 Sample Collection For shale shakers, a box will be needed to collect the discharge from the entire width of the shaker screens. A wooden core box can be used, or have a box fabricated. For mud cleaners, hydrocyclones or centrifuges, a 5 gallon bucket may be used. The larger the sample collected, the more accurate the results. 1.
Weigh the sample container before collecting the sample.
2.
Measure the sample collection time.
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Appendix C
SOLIDS CONTROL HANDBOOK
January 1998
Solids Control Equipment Discharge Analysis, Oil Based Muds
Page 2 of 7
Schlumberger Dowell
3.
Record the weight of the container and wet solids.
4.
Calculate the mass flow rate of the wet solids, mws, in lbm/min.
3 Retort Procedure 1.
Weigh the empty retort W1, gm.:
2.
Fill with a representative sample of wet solids and weight, W2, gm.
3.
Run retort. Weigh retort and dry cuttings, W3, gm.
4.
Record Volume of oil, Vo, and Volume of water, Vw, recovered.
5.
Weight of wet solids, gm: W ws = W2 - W1
6.
Density of wet solids:
rs = Wws/Vt 7.
Weight of dry solids (including salt), gm: W ds = W3 - W1
4 Alternate Retort Procedure for Air-Entrained Cuttings Samples Occasionally, there will not be sufficient liquid on the wet solids to avoid entrainment of air in the retort. This will cause errors in the retort calculations. The following procedure may be used if a problem with air entrainment is anticipated: 1.
Place the retort cup lid on the retort cup. Place entire assembly on a balance. Record the weight of retort cup, lid, expansion chamber and steel wool as W1, gm.
2.
Fill the cup approximately 3/4 full with wet cuttings. Weigh the wet cuttings, retort cup, lid, expansion chamber and steel wool. Record as W 2, gm.
3.
With a syringe, fill the retort cup with oil until the cuttings are covered. Carefully stir cuttings to remove entrapped air.
4.
Place the lid on retort cup. Using the syringe and needle, fill retort cup with oil through the hole in the cup lid.
5.
Weigh the wet cuttings/oil mixture, retort cup, lid, expansion chamber and steel wool. Record as W3.
6.
Run retort. Record Volume of oil, Vto, and Volume of water, Vw, recovered.
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Appendix C
SOLIDS CONTROL HANDBOOK Schlumberger Dowell
January 1998
Solids Control Equipment Discharge Analysis, Oil Based Muds
Page 3 of 7
7.
Allow retort to cool. Weigh dry solids, retort cup, lid, expansion chamber and steel wool. Record as W4.
8.
Weight of wet solids, gm: W ws = W2 - W1
9.
Weight of dry solids (including salt), gm: W ds = W4 - W1 3
10. Volume of oil added by syringe, cm : Voa = (W3 - W2)/SGoil 3
11. Corrected oil on cuttings Volume, cm : Vo = Vto - Voa 3
12. Corrected retort Volume, cm : Vt = 50 ml - Voa
5 Solids Analysis Calculations Note: Use brine density, rb, and Wt% salt, %S, recorded on mud check. 1.
Density of wet solids:
rws = Wws /Vt 2.
Weight of oil, gm: W o = Vo * SGoil
3.
3
Volume of brine, cm : Vb = 100 (Vw)/(rb(100 - %S))
4.
3
Corrected dry solids Volume, cm : Vs = (Vt - Vo - Vb)
5.
Corrected dry solids weight, gm: W s = (Wws - Wo - (Vb * rb)
6.
3
Dry solids density, gm/cm :
rs = Ws/Vs 7.
Corrected Volume% solids: %Vs = 100 * Vs/Vt
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Appendix C
SOLIDS CONTROL HANDBOOK
January 1998
Solids Control Equipment Discharge Analysis, Oil Based Muds
Page 4 of 7
8.
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Volume% high-density solids (% of wet slurry): %HDS = %Vs (rs - 2.65)/(SGHDS - 2.65)
9.
Volume% low-density solids (% of wet slurry): %LDS = %Vs - %HDS
10. High-density solids concentration, lb/bbl: HDS = 3.5 (SGHDS) (%HDS) 11. Low-density solids concentration, lb/bbl: LGS = 3.5 (SGLGS) (%LGS) 12. Weight% oil to dry solids: %Oil = (Wo/Ws) * 100 13. Total discharge rate, bbl/hr: Qt = (60) (ms)/((350) (rws)) 14. Solid discharge rate, bbl/hr: Qs = (%Vs) (Qt)/100 15. Liquid discharge rate, bbl/hr: Ql = Qt - Qs 16. High-density solids mass flow rate, lb/hr: mHDS = (Qt) (HDS) 17. Low-density solids mass flow rate, lb/hr: mLDS = (Qt) (LDS) 18. Check HDS/LDS ratio of discharge to HDS/LDS ratio of mud If HDS/LDS > HDS/LDS of mud, then barite is being preferentially removed.
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Appendix C
SOLIDS CONTROL HANDBOOK Schlumberger Dowell
January 1998
Solids Control Equipment Discharge Analysis, Oil Based Muds
Page 5 of 7
6 Example Calculations The following example calculations are designed to show how the equations listed in this section may be used to determine the composition and rate of the solid and liquid discharge streams.
Sample Source: Shaker discharge Mud Check Data Brine phase density, gm/cm
Symbol 3
rb
1.24
Wt% Salt in Brine
%S
26.7
Barite, lb/bbl
HDS
100.0
Low Gravity Solids, lb/bbl
LDS
75.0
Drilled Solids Specific Gravity
SGLGS
2.65
Barite Specific Gravity
SGHDS
4.2
Sample Data Net Sample Weight, lb
60.0
Sampling time, min
1.0
Mass flow rate, lb/min
mws
60.0
Weight of empty retort, gm
W1
297.0
Weight of retort and wet solids, gm
W2
391.5
Weight of retort and dry solids, gm
W3
378.0
Vo
17.0
Vw
6.0
Vt
50.0
Retort Data
Volume of oil recovered, cm
3
Volume of water recovered, cm Total Volume retorted, cm
3
3
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Appendix C
SOLIDS CONTROL HANDBOOK
January 1998
Solids Control Equipment Discharge Analysis, Oil Based Muds
Page 6 of 7
7 Calculations 1.
Weight of wet solids: W ws = W2 - W1 = 391.5 - 297 = 94.5 gm
2.
Density of wet solids:
rws = Wws/Vt = 94.5/50.0 = 1.89 gm/cm 3.
3
Weight of dry solids (including salt), gm: W ds = W3 - W1 = 378 - 297 = 81 gm
4.
Weight of oil, gm: W o = Vo * SGoil = (17) (0.84) = 14.28 gm
5.
3
Volume of brine, cm : Vb = 100 (Vw)/(rb(100 - %S)) 3
= (100) (6)/(1.24 (100 - 26.7)) = 6.6 cm 6.
3
Corrected dry solids volume, cm : Vs = (Vt - Vo - Vb) 3
= 50 - 17 - 6.6 = 26.4 cm 7.
Corrected dry solids weight, gm: W s = (Wws - Wo - (Vb * rb) = 94.5 - 14.3 - (6.6) (1.24) = 72.0 gm
8.
3
Dry solids density, gm/cm :
rs = Ws/Vs = 72.0/26.4 = 2.73 gm/cm 9.
3
Corrected Volume% solids: %Vs = 100 * Vs/Vt = (100) (26.4)/(50) = 52.8%
10. Volume% high-density solids (% of wet slurry): %HDS = %Vs (rs - 2.65)/(rHDS - 2.65) = 52.8 (2.73 - 2.65) / (4.2 - 2.65) = 2.73%
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Schlumberger Dowell
SOLIDS CONTROL HANDBOOK Schlumberger Dowell
Solids Control Equipment Discharge Analysis, Oil Based Muds
Appendix C January 1998 Page 7 of 7
11. Volume% low-density solids (% of wet slurry): %LDS = %Vs - %HDS = 52.8 - 2.73 = 50.07% 12. High-density solids concentration, lb/bbl: HDSdis = 3.5 (rHDS) (%HDS) = 3.5 (4.2) (2.73) = 40 lb/bbl 13. Low-density solids concentration, lb/bbl: LGSdis = 3.5 (SGLGS) (%LGS) = 3.5 (2.65) (50.07) = 464 lb/bbl 14. Weight% oil to dry solids: %Oil = (Wo/Ws) * 100 = (14.28/72.04) (100) = 19.8% 15. Total discharge rate, bbl/hr: Qt = (60) (ms)/((350) (rws)) = (60) (60)/((350) (1.89) = 5.44 bbl/hr 16. Solid discharge rate, bbl/hr: Qs = (%Vs) (Qt)/100 = (52.8) (5.44)/100 = 2.87 bbl/hr 17. Liquid discharge rate, bbl/hr: Ql = Qt - Qs = 5.44 - 2.87 = 2.57 bbl/hr 18. High-density solids mass flow rate, lb/hr: mHDS = (Qt) (HDS) = (5.44) (40) = 216 lb/hr 19. Low-density solids mass flow rate, lb/hr: mLDS = (Qt) (LDS) = (5.44) (464) = 2523 lb/hr 20. Check HDS/LDS ratio of discharge to HDS/LDS ratio of mud Discharge HDS/LDS/Mud HDS/LDS (40/464)/(100/75) = 0.06 Since ratio is << 1.0, shaker is not preferentially removing barite.
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