International Journal of Information Technology and Computer Science (IJITCS)
IJITCS Vol. 3, No. 3, 8 Jun. 2011
Cover page and Table of Contents: PDF (size: 195KB)
Rheological Behaviors of Bio-degradable Drilling Fluids in Horizontal Drilling of Unconsolidated Coal Seams
Full Text (PDF, 195KB), PP.1-7
Views: 0 Downloads: 0
Index Terms
Bio-degradable drilling fluid, coalbed methane, rheological, unconsolidated coal seam, enzyme
Abstract
In China, horizontal drilling techniques have been widely used in the exploration of coalbed methane (CBM). The drill-in fluids, especially in unconsolidated coal seams, are typically comprised of cellulose polymers, xanthan polymers and guar gums. However, testing and experience have shown that insufficient degradation of filter cakes resulting from even this “clean” drill-in fluids can significantly impede flow capacity at the wellbore wall. Past approaches to minimizing the damage have been the application of strong acids or oxidative breakers systems. They are often only marginally successful, particularly when applied in extended length intervals. Therefore, this paper introduced an engineered technique incorporating non-toxic, environment friendly and economically attractive bio-degradable drilling fluids (BDF).
Extensive lab tests were conducted to evaluate the effects of substrate (polymer) type, substrate concentration, enzyme type and enzyme concentration on the viscosity breaking behaviors of BDFs. We got the conclusions as follows. (1) Power Law model was the best model to matching the rheological properties of BDFs; (2) Compared with konjak, the degradations of Na-CMC and guar gum were easier to be controlled; (3) In the degradation of CMC by enzyme SE-1, the optimal weight concentration ratio of CMC to SE-1 was 3 to 1; (4) Of the three enzymes, enzyme SE-2 had the highest activity and could be used to degrade polymer in shorter time; (5) Higher enzyme concentration could speed up the degradation reaction; (6) Viscosity breaking times fluctuating from 13.5 hours to 74.5 hours and viscosity breaking ratios varying from 20% to 100% could be achieved by modifying the formulations of BDFs.
Cite This Paper
Cai Jihua, Gu Sui, "Rheological Behaviors of Bio-degradable Drilling Fluids in Horizontal Drilling of Unconsolidated Coal Seams", International Journal of Information Technology and Computer Science(IJITCS), vol.3, no.3, pp.1-7, 2011. DOI:10.5815/ijitcs.2011.03.01
Reference
[1]LeBlanc, Leonard, “Limiting, treating formation damage in horizontal, extended reach wells,” Offshore, June 1996, pp.58.
[2]Brian B. Beall, Robert Tjon-Joe-Pin, and Harold D. Brannon, “Field experience validates effectiveness of drill-in fluid cleanup system,” SPE 38570, 1997.
[3]McClarty, J.M., Dobson, J.W. and Dick, M.A, “Overview of offshore horizontal drilling/completion properties in unconsolidated sand stones in the Gulf of Mexico,” OTC 7352, 1993.
[4]Len V. Baltoiu, Brent K. Warren, Thanos A. Natras, “State-of-the-Art in Coalbed Methane Drilling Fluids,” SPE Drilling & Completion, 2008, 23(3), pp. 250-257.
[5]K. Barr, “A guideline to optimize drilling fluids for coalbed methane reservoirs”, SPE 123175, 2009.
[6]Lai Xiaoqing, Lou Yishan, Qu Yuanzhi, et al, “State-of-the-art & development clue in drilling fluid technologies of coalbed methane exploitation in China,” Journal of Oil and Gas Technology (Journal of Jianghan Petroleum Institue), 2009, 31(5), pp. 326-328.
[7]Beall, B.B., Brannon, H.D., TjonJoePin, R.M., O'Driscoll, K, “Evaluation of a new technique for removing horizontal wellbore damage attributable to drill-in filter cake,” SPE 36429 ,1996.
[8]R.M. Hodge, B.G. Augustine, R.C. Burton, W.W. Sanders, Donna Atkinson, “Evaluation and selection of drill-in-fluid candidates to minimize formation damage,” SPE Drilling & Completion, 1997, 12(3): pp.174-179.
[9]Burnett, D.B, ‘‘Using a physical wellbore model to study formation damage problems in well completions,’’ SPE 27393, 1994.
[10]Tjon-Joe-Pin, Robert, Brannon, H.D., Rickards, A. R., ‘‘Remedial treatment for polymeric damage removal provides improved well productivity,” SPE 25214, 1993.
[11]A. R. Rickards, R. M. Tjon-Joe-Pin, and J. L. Boles, ‘‘Enzymatic breaker system for non-damaging removal of cellulose-based blocking gels,” SPE 25488,1993.
[12]H.D. Brannon, R. M. Tjon-Joe-Pin, “Biotechnological breakthrough improves performance of moderate to high-temperature fracturing applications,” SPE 28513, 1994.
[13]H.D. Brannon, R. M. Tjon-Joe-Pin, ‘‘Application of damage removal treatment results in multi-fold well productivity improvement: a case study,” SPE 29677, 1995.
[14]TjonJoePin, R.M.,et al, “Method of dissolving organic filter cake obtained from polysaccharide based fluids used in production operations and completions of oil and gas wells,” U.S. Patent No 5,247,995(1993).
[15]K.P. O’Driscoll, N.M. Amin, I.Y. Tantawi, ‘‘New treatment for removal of mud-polymer damage in multilateral wells drilled using starch-based fluids,” SPE Drilling & Completion, 15(3), 2000, 167-176.
[16]Harris, R.E., McKay, I.D., ‘‘New applications for enzymes in oil and gas production,” SPE 50621, 1998.
[17]Cai Ji-hua, Gu Sui, Liu Hao, “Experimental study on bio-degradable drilling fluid in Gas extracting drilling of unconsolidated and soft coal seam”, Progress in Safety Science and Technology, Vol.VIII, 2010, pp. 1463-1469.
[18]Cai Jihua, Liu Hao, Gu Sui, “Empirical correlation to predict viscosity breaking ratio of guar-based biodegradable drilling fluid, ” ICIECS 2010, pp. 5-8.