Info

Dtcwrr

May be uari »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 liquid»

May oie 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 deniable

Lk^iKwatroiutn biodegradable >t to* i'H

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

Not de«radable

Koamers, additivo *f« 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 not be luf rnfui prrjVnJt J cl.n.-.jji'.p s afe uot used

Polymer mud» «htmld not 1m bifrtifid u king aa chromic <xanp<niivia aiwl i lilorophcnile hicKrfiaeidr* are exe'udctl-

Oil ruuda art ik> more liuardoua than oil and abould praent no problems with adequate controls against spillage and an adequate daposal system

Foam drilling compatible with ecology »nice relatively »mill volumes of liquids are used. Drld. cuttings are large and no dust is generated

Air drl(. can result in teriotu duit problem line* 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 kdeuual* to fill hole on trip«, normally 300 to i0G bbJn.

Adequate to till hrtle hi trip«

2*1 to 100 bbl divided tank in rJed so that foaiuable solution can be mixed & used alternately

10 to 20 bbl. fOamer tank for misting

May be small to very large if used for settling

Should b« id equate to displace eem*nt

Should br adequate to displace cement and for feat circulation

May require two tanks; one 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 waitc liquid«

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

Mint be »^tiMe ronUin tarse volume of hul* »ilnda and »mailer volumes 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 raaent ¡«I

Mitrjld be prujier tie 1tht, sire 3r d k<al inn [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 centrifuging 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

1. Fertl, W. H. and Chilingar, G. V., "Importance of Abnormal Formation Pressures" J. Petrol, Tech. (April, 1977). pp. 347-354.

2. Breckels, I. M., and Van Eekelen, H. A. M., "Relationship Between Horizontal Stress and Depth in Sedimentary Basins," J. Petrol. Technol. (Sept., 1982) pp. 2191-2199.

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.

6. Eckel, J. R., "Effect of Pressure on Rock Drillability," Trans. AIME, Vol 213 (1958). pp. 1-6.

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.

14. Outmans, H. D., "Mechanics of Differential-Pressure Sticking of Drill Collars," Trans. AIME, Vol. 213 (1958). pp. 265-274.

15. Haden, E. L., and Welch, G. R., "Techniques for Preventing Differential-Pressure Sticking of Drill Pipe," API Drill. Prod. Prac. (1961). pp. 36-41.

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.

17. Hutchison, S.O., and Anderson, G. W, "What to Consider When Selecting Drilling Fluids," World Oil (Oct., 1974). pp. 83-94.

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.

20. McAuIiffe, C, D., and Palmer, L. L., "Environmental Aspects of Offshore Disposal of Drilling Fluids and Cuttings," SPE Paper 5864, Regional Meeting, Long Beach. April 8-9, 1976.

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.

28. Carter, T. S., "Rig Preparation for Drilling with Oil Based Muds," IADC/SPE paper 13436, Drilling Conference, New Orleans, March, 1985.

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.

29a. 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.

30. Burton, J . and Ford, T., "Evaluating Mineral Oils for Low-Toxicity Muds," Oil & Gas J. (July 29, 1985). pp. 129-131.

31. Goodman, M. A., "Arctic Drilling Operations Present Unique Problems," World Oil (Nov., 1977). pp. 95-110.

31a. Fräser, I. M., and Moore, R. H., "Guidelines for Stable Foam Drilling through Permafrost," SPE/IADC paper 16055, Drill. Conf., March 15-18, 1987, New Orleans, LA.

32. Walker, T. O., Dearing, H. L., and Simpson, J. P., "Potassium Modified Lime Muds Improve Shale Stability," World Oil (Nov., 1983). pp. 93-100.

33. Walker, T. O., Dearing, H. L., and Simpson, J. P., "The Role of Potassium in Lime Muds," SPE paper 13161, Annual Meeting, Houston, Sept. 16-19, 1984.

34. de Boisblanc, C. W., "Water Mud Gives Advantages with PCD Bits," Oil & Ga^ J (April 1, 1985). pp. 134-137.

35. Thomas, D. C., "Thermal Stability of Starch and Carboxymethyl Cellulose-Based Polymer," Soc. Petrol. Technol. J. (April, 1982). pp. 171-180.

36. Sheffield, J. S., and Sitzman, J. J., "Air Drilling Practices in the Midcontinent and Rocky Mountain Areas," IADC/SPE paper 13490. Drilling Conference, New Orleans, March, 1985.

37. Zcidler, H. U., "Better Understanding Permits Deeper Clear Water Drilling." World Oil (June, 1981). pp. 167-178.

38. Simpson, J. P., "Low-Colloid Oil Muds Cut Drilling Costs," World Oil (April. 1979). pp. 167-174.

39. Golis, S. W., "Oil Mud Techniques Improve Performance in Deep, Hostile Environment Wells," SPE paper 13156, Annual Meeting, Houston, Sept. 1984.

40. Denny, J. P., and Shannon, J. L., "New Way to Inhibit Troublesome Shale," World Oil. (July, 1968). pp. 111-117.

41. Hoberock, L. L., "Shale-Shaker Selection and Operation," Part 1: Oil Gas J. (Nov. 23. 1981). pp. 107-113; Part 2: Oil Gas J. (Dec. 7, 1981). p. 130-141.

42. Williams, M., and Hoberock, L., "Solids Control for the Man on the Rig, Pt. 1 —Solids Removal Economics and Shaker Selection," Petrol. Eng. (Oct. 1982). pp. 58-84.

43. Ormsby, G. S., "Desilting Drilling Muds with Hydrocy clones," Drilling Contract. (March/April, 1965). pp. 55-65.

44. Ormsby, G. S,, "How Proper Desilting Helps in Unweighted Mud Drilling," Drilling (June, 1966). pp. 53, 54.

45. White, D. W., "Hydrocyclones Performance Predicted by Settling Rate," Oil Gas J. (Oct. 11, 1982). pp. 151-156.

46. White, D. L., "Tests Show Differences in Cyclones," Oil Gas J. (Oct. 25, 1982). pp. 151-157.

47. Williams, M. P., "Solids Control for the Man on the Rig, Part 2—Hydrocyclonc and Centrifugal Pump Sizing," Petrol. Eng. (Nov. 1982). pp. 102-110.

48. Robinson, L. H., and Heilhecker, J. K., "Solids Control in Weighted Drilling Fluids," J. Petrol. Technol. (Sept. 1975). pp. 1141-1144.

49. Bobo, R. A., and Hoch, R. S., "Mechanical Treatment of Weighted Drilling Muds," Trans. AIME, Vol. 201 (1954). pp. 93-96.

50. Burdyn, R. F., and Nelson, M. D., "Separator Refines Deep Well Mud Control" Petrol. Eng. (July, 1968). pp. 68-72.

51. Dawson, R., and Annis, M. R., "Total Mechanical Solids Control," Oil Gas J. (May 30, 1977). pp. 90-100.

51a. Wojianowicz, A. K., "Modern Solids Control: A Centrifuge Dewatering Study." SPE/IADC paper 16098, Drill. Conf., March 15-18, 1987, New Orleans, LA

52. Hayatdavoudi, A., "Downhole Solids Control: A New Theory and Field Practice," SPE paper 14383, Annual Meeting, Las Vegas, Sept. 22-25, 1985.

53. Ormsby, G. S., "Drilling Fluid Solid Removal," in "Drilling Practices Manual" by P.,L. Moore, The Petroleum Publishing Co., Tulsa, 1974, pp. 133-204.

54. 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.

54a. 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.

55. Ormsby, G. S., "Proper Rigging Boosts Efficiency of Solids Removing Equipment," Oil Gas J. (March 12, 1973). pp. 120-132.

56. Ormsby, G. S., "Correction of Common Errors in Drilled Solids Removal Sy stems" Proc. Second Adriatic Symp. on Oil Well Drilling, Porec, Yugoslavia, May 7-10, 1973. pp. 284-302.

57. White, D. L., "Good Field Practice Helps Cyclones Do the Job," Oil Gas J. (Nov 8, 1982). pp. 211-223.

58. 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.

59. 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.

60. Lummus, J. L., "Analysis of Mud Hydraulics Interactions," Petrol. Eng. (Feb 1974). pp. 60-69.

61. Lummus, J. L., "Drilling Optimization," J. Petrol. Technol. (Nov., 1970). pp. 1379-1389.

62. Lummus, J. L.. "Acquisition and Analysis of Data for Optimized Drilling," J. Petrol. Technol. (Nov., 1971). pp. 1285-1293.

63. 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.

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