Solids Removal Equipment

The importance of removing drilled solids has been emphasized several times in the preceding sections. The advantages of doing so may be summarized as follows:

  1. Less barite and mud additives required.
  2. Better rheological properties because the reduction in plastic viscosity increases the YP/PV ratio, thereby promoting shear thinning.
  3. Lower plastic viscosity facilitates the removal of entrained gas, hence lower mud densities can safely be carried.
  4. Faster drilling rates, because of lower viscosity and drilled solid content.
  5. Less risk of sticking the pipe, because of thinner filter cakes.
  6. Less bit wear.

The results of a field study, shown in Figure 1-7, illustrate the relationship between rig costs and solids content. Such savings are generally much greater than the cost of renting and running solids removal equipment.

The various pieces of equipment and their purpose are briefly, as follows:

Double deck shakers41,42 are used to remove cuttings and coarse aggregates. They have a coarse screen, say 40 mesh, on top and an 80 mesh below. Double deck shakers are particularly advantageous when drilling shales because the 80 mesh screen removes aggregates of shale which would otherwise become dispersed and much more difficult to remove. Some modern high efficiency shakers are capable of removing almost all of the first time circulated solids from shale muds. Development of an improved vibratory motion enables a 150 mesh screen to be used on the lower deck.

Table 1-4 Mud System Equipment Requirements

Non-dispersed

Equipment

Water/light treated day

Dispersed weighted

Unweighted

Weighted

Oil muds

Preformed stable foam

Gas, air and mist

Wellhead

BOPs

A« required for well control

As required for kick control

As required for kick control

As required for well control

Generally 1 positive, 1 pipe ram & Hydril

As required for control

Rotating head or stripper

May be used for under bal. drlg.

May be used for under bal, drlg.

May be used for under bal. drlg.

Not used

Essential to divert foam. Use rotating head w/Kelly and a stripper w/power swivel

Essential to divert returns to waste sump

Variable choke

May be used for back pressure control

Essential for kick control

Essential for kick control. May be used for back pressure control

Essential for kick control

Essential for back pressure control

Not used

Surge chamber and mud separator

Not used

Essential for kick con

Essential for kick control to reclaim itas cut

Surg« chamber or cyclone type foam sup-preMor when foaming into a tank

Not used

trol to save gas cut mud

mud

pensive mud when gas cut

Discharge lines

Flow line to shakers

Flow line to shakers, choke line to surge tank and waste sump

Flow line to shakers, choke line to surge tank and to waste sump

Flow line to shakers, choke line to surge tank and/or separator

Blooey line to waste or surge tank

Blooey line to waste sump

Solids removal Shaker screen

Dual w/med. screens

Dual w/med. to fine screens

Double deck w/ med. & fine screens

Double deck med. & fine screens

Dual w/med. to fine. Double deck w/fine

Sand trap

20-30 bbl. w/tt* bottom-large dtftin. Jump

B* careful not to dump liquid mud

Important to settle coarse material ahead of QCMDder-desilter units

Important to settle sand. Be careful of mud loss

No solids removal equipment needed. Normally, foam is a one-pass system, foam and solids go to waste sump

No solids removal equipment used.

Air and solids to waste sump

U< jander

Importaut-run ahead of desiltera

May be used to remove coarae materia] ahead of desilting equipment

Important to prevent overloading desilters or centrifuge

Can be used by dumping into tank of solvent

Desilter

Important to remove fine silts for low weight

Not used

Essential for low solids muds

Not recommended

Not used

Mud cleaner

Important to remove fine silts for low weight

Excludes It. solids on medium weight mud

Essential for drilled solids control

Useful on Medium weight muds

Not used

Centrifuge

Not used

Eaw&tial for economic control of high wt, mnda

May be uaed to reclaim liquids and dump drilled solids

Essential for high wt. mud control

Can be used to reduce wt.

Dtcwrr

May be uarl »ht ad u( treatment if (is encountered

Ka*nii»l in kick control for true »1»

K*ential (or good kick conlrol practice

Can be used if gas cuttag a problem

Can use gas Lnp to separate ¿u and liquids

May uie low pressurn trap U> rttlaim i»

Equipment

Water/light treated clay

Dispersed weighted

N'on-ditpersed

Oil muds

Preformed stable foam

Gas, air and mist

Unweighted Weighted

Biodegradalilitf

Not tksndiWi

Lk^iKwatroiutn biodegradable >t to* i'H

Mart paly intra, »Urdu-*, CMC are biodegradable

Not de«radable

Koamers, additivo are biodegradable

Foamere used in mist are biodegradable

»flee!«

Fnsli water clay mud« can be iwy bctwiicisl to tuiU, particularly sandy soils. Sodium polyphosphates used as thinners degrade to ortho phosphate fertilizer. Lignite, lignins and tanning are humic acids

I.j ri nowulfosi at ¡nude ihouM ntii be harmful prrjVnJt J cl.n.-.jji'.p s afe uot used

Polymer mud» «htmld not 1m harmful u king aa chrwrn: aanpwivla aiwl i lilorophcnile hicKrfiaeidr* are exe'udetl-

Oil ruuda «rt ik> nwre liuardoua than oil and abould prtaent no problems with adequate controls against apill-'*t,e and an adequate daposal system

Foam drilling com pat" ibit with ecology »nice relatively small volumes of liquids are used. Drld. cuttings are large and no dust is generated

Air drl(. can result in teriotu duit problem liar* cut t i op are (round very fine and blown out with air. Addition of foamer help«, but does not cure completely

Liquid storage Active

Reserve Waste

May be small to very large, depends on depth and lost circulation

Must be adequate to fill hole on trips; normally 300 to 700 bbls.

Must be kdeuutl* to fill hole on trip«, normally 300 to i0G bbJn.

Adequate to till hrtle hi trip«

2*1 to 100 bbl divided tank lu rried 30 that foaiuable solution can be mixed & used alternately

10 to 20 bbl. fOamer tank for mist,ins

May be small to very large if used for settling

Should b« id equate to displace eem*m

Should br adequate to displace cement and for feat circulation

May require two tanks; otv> ffir new It. wt mud, one foe heavier mud

Not needed if water supply adequate, may be used to recycle foam solution

None

Mail be adequate to contain drtd. *o)h1* and wailc liquid«

Adequate to i-nnlain «mailer volume» of drW, *oUlv and tn)uxi»

Mint Iw »^tlMe nut U in targe volume of hul* »ilnda and »mailer vulunws of nwte liquid«

Minimal since only solids dumped, expensive mud saved

Lour [lit. desirable to contain surging foam return«

Dry dust difficult t<-contain

Dry storage

Aik^iuU (or (B'jd *rtd rhemtfialt

Proper heidil »nd aiie eaaent ¡«I

Mitrjld be prujier tieiiht, sire 3rd k<al«"n [of mud iru) f ljF-nina.1

Adequate for mud and chemical

Not normally needed

Not, needed

Dewatering Surplus Mud. Full-scale experiments by Wojianowicz51a have shown that it is possible to remove clay colloids from the surplus mud by flocculating it with chemicals before centrifiiging it. The process results in practically solids-free water and wet mud cake, which is much easier to dispose of than liquid mud.

Downhole solids control." A sub, which is placed directly above the bit, contains a high efficiency cone that separates the mud into two fractions: a heavy fraction containing the removed solids, which is directed through two upjets into the annulus; and a lighter fraction that passes on to the bit. In two field tests, increases in penetration rate up to 58% and improved bit life were obtained when drilling in shale.

For effective removal of drilled solids, it is essential that the shakers and hydrocyclones have enough capacity to handle the whole mud stream. Often, it is necessary to have two units operating in parallel. Dawson and Annis51 report that by using sufficient numbers and types of separators, they were able to remove all the drilled solids from an unweighted mud in a well in Wyoming. Obviously, the amount of drilled solids that can be removed depends on the dispersion of the formation being drilled and on the type of mud being used. For instance, use of a nondispersing polymer-brine mud greatly assists in solids removal.

The benefits of solids removal will be much less if the system is not properly designed and efficiently maintained. Unfortunately, this is often the case. An investigation by Williams and Hoberock42 found that virtually every one of 35 wells investigated had some significant error in design or maintenance. Similar results were found by Kelly.18 The factors to be considered in selecting and sizing the various units discussed above are given in the references quoted for them. Design of the system as a whole is discussed by Ormsby,53 and Young and Robinson,54 and Muchter and Edelbrock.54a Proper fluid routing is emphasized by Ormsby,55 56 Williams,58 and Kelly.18

A computer driven simulator that takes into account all relevant factors involved in the drilling process has been developed by Skidmore and Anderson59 to facilitate the design and optimization of solids control systems.

Optimization

Optimized drilling involves the selection of operating conditions that will require the least expense in reaching the desired depth, without sacrificing requirements of personnel safety, environmental protection, adequate information on penetrated formations, and productivity. J. L. Lummus60 states that the drilling fluid is probably the most important variable to be considered in optimization, and that hydraulics is second. Selection of the drilling fluid is based on its rela tive ability to drill the formations anticipated, while affording effective hole cleaning and well-bore stabilization. In earlier papers, Lummus61,62 identities the significant variables involved in drilling optimization, lists the sources ot information, and cites examples of applications.

In a series of papers on mud hydraulics, R. E. Walker63,64-65-66-67'^'69 examines mud characteristics and flow rates as related to optimum performance. The widespread uses of drilling assistance programs has demonstrated their applicability.70 Examples of cost reduction effected by drilling optimization on wells in Montana7' and in southwestern Oklahoma72 have been reported.

Well-site application of computers in data monitoring, storage, analysis, and presentation has made practical the critical evaluation of the program while drilling is in progress.73-74

References

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  3. Daines, S. R., "Predictions of Fracture Pressures in Wildcat Wells," 7. Petrol, Technol. (April, 1982). pp. 863-872.
  4. Stuart, C. A., "Geopressures," Supplement to Proc. Abnormal Subsurface Pro sure, Louisiana State University, (Jan. 30, 1970).
  5. Murray, A. S., and Cunningham, R. A., "Effect of Mud Column Pressure on Drilling Rates," Trans. AIME, Vol. 204 (1955). pp. 196-204.
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  7. Cunningham, R. A., and Eenink, J. G., "Laboratory Study of Effect of Overburden, Formation and Mud Column Pressures on Drilling Rate of Permeable Formations," Trans. AIME, Vol. 216 (1959). pp. 9-17.
  8. Gamier, A. J., and van Lingen, N. H., "Phenomena Affecting Drilling Rates at Depth," J. Petrol. Technol (Sept., 1959). pp. 232-239.
  9. Vidrine, D. J., and Benit, E. J., "Field Verification of the Effect of Differential Pressure on Drilling Rate," J. Petrol. Technol. (July, 1968). pp. 676-681.
  10. Burkhardt, J. A., "Wellbore Pressure Surges Produced by Pipe Movement," ./. Petrol. Technol. (June, 1961). pp. 595-605; Trans. AIME, Vol. 222.
  11. Schuh, F. J., "Computer Makes Surge-Pressure Calculations Useful," Oil Gas J., (August 3, 1964). pp. 96-104.
  12. Fontenot, J. E., and Clark, R. K., "An Improved Method for Calculating Swab and Surge Pressures and Circulating Pressures in a Drilling Well," Soc. Petrol. Eng. J, (Oct., 1974). pp. 451-462.
  13. Helmick, W. E., and Longley, A. J., "Pressure-Differential Sticking of Drill Pipe and How It Can Be Avoided or Relieved," API Drill. Prod. Prac. (1957). pp. 5560.
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  16. Annis, M. R., and Monaghan, P. H., "Differential Pressure Sticking—Laboratory Studies of Friction Between Steel and Mud Filter Cake," J. Petrol. Technol. (May, 1962). pp. 537-543; Trans. AIME, Vol. 225.
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  18. Kelly, J., "Drilling Fluids Selection, Performance and Quality Control," J. Petrol, Techno!. (May, 1983). pp. 889-898.
  19. Environmental Aspects of Chemical Use in Well-Drilling Operations, Conference Proceedings, Houston, May, 1975. Office of Toxic Substances, Environmental Protection Agency, Washington, Sept., 1985.
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  21. Monaghan. P. H., McAuIiffe, C. D., and Weiss, F. T., Environmental Aspects of Drilling Muds and Cuttings from Oil and Gas Extraction Operations in Offshore and Coastal Waters, Offshore Operators Committee, New Orleans, May, 1976.
  22. Ayers, R. C., Sauer, T. C., and Anderson, R. W., "The Generic Mud Concept for NPDES Permitting of Offshore Drilling Discharges," J. Petrol Technol (March. 1985). pp. 475-480.
  23. Hinds, A. A. and Clements, W. R., "New Mud Passes Environmental Tests," SPE paper 11113, Annual Meeting, New Orleans, Sept. 1982.
  24. Boyd, P. A., Whitfill, D. L., Carter, D. S., and Allamon, J. P., "New Base Oil Used in Low-Toxicity Oil Muds," SPE paper 12119, Annual Meeting, San Francisco, Oct. 1983; and J. Petrol. Technol. (Jan. 1985) pp. 137-142.
  25. Jackson. S. A. and Kwan, J. T., "Evaluation of a Centrifuge Drill-Cuttings Disposal System With a Mineral Oil-Based Drilling Fluid on a Gulf Coast Offshore Drilling Vessel," SPE paper 13157, Annual Meeting, Houston, Sept. 1984.
  26. Bennett. R. B., "New Drilling Fluid Technology—Mineral Oil Mud," J. Petrol. Technol. (June, 1984). pp. 975-981.
  27. Kelley, J. Jr., Wells, P., Perry, G. W., and Wilkie, S. K.. "How Using Oil Mud Solved North Sea Drilling Problems," J. Petrol. Technol. (June, 1980). pp. 931940.
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  29. Wally, B. F., Reitsema, L. A., and Nance, G. W., "Treatment of Drilling Fluids Wastes in an Environmentally Acceptable Manner," IADC/SPE paper 13456, Drilling Conference, New Orleans, March, 1985.
  30. Johancsik, C. A., and Grieve, W. A., "Oil-Based Mud Reduces Borehole Problems," Oil Gas J. (April 27, 1987) pp. 46-58 and (May 4, 1987) pp. 42-45.
  31. Burton, J . and Ford, T., "Evaluating Mineral Oils for Low-Toxicity Muds," Oil & Gas J. (July 29, 1985). pp. 129-131.
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  34. Walker, T. O., Dearing, H. L., and Simpson, J. P., "Potassium Modified Lime Muds Improve Shale Stability," World Oil (Nov., 1983). pp. 93-100.
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  47. White, D. W., "Hydrocyclones Performance Predicted by Settling Rate," Oil Gas J. (Oct. 11, 1982). pp. 151-156.
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  50. Robinson, L. H., and Heilhecker, J. K., "Solids Control in Weighted Drilling Fluids," J. Petrol. Technol. (Sept. 1975). pp. 1141-1144.
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  52. Burdyn, R. F., and Nelson, M. D., "Separator Refines Deep Well Mud Control" Petrol. Eng. (July, 1968). pp. 68-72.
  53. Dawson, R., and Annis, M. R., "Total Mechanical Solids Control," Oil Gas J. (May 30, 1977). pp. 90-100.
  54. Wojianowicz, A. K., "Modern Solids Control: A Centrifuge Dewatering Study." SPE/IADC paper 16098, Drill. Conf., March 15-18, 1987, New Orleans, LA
  55. Hayatdavoudi, A., "Downhole Solids Control: A New Theory and Field Practice," SPE paper 14383, Annual Meeting, Las Vegas, Sept. 22-25, 1985.
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  57. Young, G. H. and Robinson, L. H., "How to Design a Mud System for Optimum Solids Removal," Part 1: World Oil (Sept. 1982). pp. 57-61; Part 2: Oct. 1982, pp. 105-110; Part 3: Nov. 1982, pp. 159-174.
  58. Muchter, J. B., and Edelbrock, G. J., "Expensive Drilling Fluids Put Focus on Solid Control Systems," Oil Gas J. (Jan. 5, 1987) pp. 33-37.
  59. Ormsby, G. S., "Proper Rigging Boosts Efficiency of Solids Removing Equipment," Oil Gas J. (March 12, 1973). pp. 120-132.
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  61. White, D. L., "Good Field Practice Helps Cyclones Do the Job," Oil Gas J. (Nov 8, 1982). pp. 211-223.
  62. Williams, M. P., "Solids Control for the Man on the Rig, Part 3—Fluid Routing. Maintenance and Troubleshooting," Petrol. Eng. (Dec. 1982). pp. 50-66.
  63. Skidmore, D. B., and Anderson, C. T., "Solids Control Design and Analysis Using an Engineering Simulator for Drilling," SPE/IADC paper 73438, Drilling Confer once. New Orleans, March 5-8, 1985.
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  65. Lummus, J. L., "Drilling Optimization," J. Petrol. Technol. (Nov., 1970). pp. 1379-1389.
  66. Lummus, J. L.. "Acquisition and Analysis of Data for Optimized Drilling," J. Petrol. Technol (Nov., 1971). pp. 1285-1293.
  67. Walker. R E., "Operating Window Outlines Drilling-Mud Optimization Limits," Oil Gas J. (Aug. 9, 1976). pp. 59-62.

64 .___"Cleaning Bits Key to High Penetration Rates," Ibid. (Aug. 16, 1976). pp.

139-145

65____. "Drilling Rate Index Specifies Optimum Cleaning," Ibid. (Aug. 30, 1976).

66 ._________, "Mud Behavior Can Be Predicted," Ibid. (Sept. 13, 1976). pp. 63-68.

67 .________, "Hydraulics Limits Are Set By Flow Restrictions," Ibid. (Oct. 4, 1976). pp.

68 .______, "Annular Calculations Balance Cleaning with Pressure Losses," Ibid. (Oct.

69. _ ____, "Operating Window Gives Best Fluid Performance," Ibid. (Nov. 1, 1976).

pp. 73-82.

  1. Randall, B. V., and Estes, J. C., "Optimized Drilling Applicable Worldwide," Petrol. Eng. (June, 1977). pp. 26-36.
  2. Korry, D E., "Optimizing Deep Drilling Programs," World Oil (Sept., 1977). pp 53-58.
  3. White, D. L., "Putting Available Know-How to Use Can Cut Drilling Costs," Oil Gas J. (Sept. 5, 1977). pp. 103-108.
  4. Young, F. S., Jr., and Tinner, K. D., "Economics Is The Key to Evaluating On-Site Well Monitoring," Oil Gas J. (July 24, 1972). pp. 50-60.
  5. Taylor, K. O., "Use of Automated Logging Units for Predicting Abnormally Pressured Formations and Well Correlation," Southwestern Petroleum Short Course, Texas Tech University, Lubbock, April 17-18, 1975.

CHAPTER 2

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  • veli-pekka
    How does gas in mud effect solids removal process?
    9 years ago

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