بررسی نفوذپذیری وابسته به تنش در مخازن شکاف‌دار با استفاده از روش عددی المان مجزاء

نوع مقاله: مقاله پژوهشی

نویسندگان

گروه مکانیک سنگ، دانشکده فنی و مهندسی، دانشگاه تربیت مدرس، تهران، ایران

چکیده

موضوع حساسیت نفوذپذیری نسبت به تنش در مخازن نفتی و گازی یک موضوع بسیار مهم و حیاتی می‌باشد، به‌طوری که تولید از یک مخزن ارتباط تنگاتنگی با ضریب حساسیت تنش آن دارد. در واقع این پدیده بدین صورت است که کاهش فشار مخازن در حالی که تنش روباره دارای مقدار ثابتی است، باعث افزایش تنش موثر و در نتیجه کاهش نفوذپذیری خواهد شد. چنانچه ارتباط دقیق بین کاهش نفوذپذیری با کاهش فشار مخازن به خوبی شناخته شود، می‌توان استخراج هیدروکربور از مخازن را اقتصادی‌تر نمود. در این مقاله با استفاده از روش عددی المان مجزاء یک کد عددی توسط نرم‌افزار UDEC توسعه داده شده است. در کد عددی توسعه داده شده تاثیر ضریب حساسیت بر‌روی پارامترهایی همانند میدان تولید چاه و ضریب پوسته در اطراف یک مخزن با جریان شعاعی بررسی شده است. برای بررسی تاثیر تنش بر‌روی نفوذپذیری شکاف‌های موجود در یک مخزن رابطه بین تنش و نفوذپذیری به‌صورت نمایی فرض شده است. بررسی‌های انجام شده نشان می‌دهد که با افزایش ضریب تراکم‌پذیری شکاف‌ها، ضریب پوسته مخزن دچار افزایش و میزان تولید از چاه دچار کاهش می‌شود. 
 

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

A Numerical Investigation on Stress Dependent Permeability in Jointed Reservoirs

نویسندگان [English]

  • Behnam Ghobadi
  • Hamid Reza Nejati
  • Kamran Goshtasbi
Rock Mechanics Division, School of Engineering, Tarbiat Modares University, Tehran, Iran
چکیده [English]

Stress dependent permeability is a great problem in petroleum engineering and natural fractured reservoirs. Permeability in a fractured porous medium is mainly controlled by the geometry and interaction of the pores and fractures as well as stress state. Interaction between stress and permeability in jointed reservoirs is a crucial factor during different stages of life of  a reservoir such as assessment, productivity and management. Also, reduction in reservoir pressure significantly influence on the reservoir permeability. In this study, it is intended to find the relationship between the stress sensitivity and production rate. For this purpose, distinct element code is used to develop numerical modeling of a reservoir to evaluate the relationship between stress sensitivity and productivity rate. The results of numerical simulations indicated that with increasing the bulk modulus of rock joints, the skin factor increases and consequently the well productivity decreases.
 

کلیدواژه‌ها [English]

  • Stress Dependent Permeability
  • Productivity Rate
  • Skin Factor
  • Distinct Element Method
  • UDEC Software

[1]. Fatt I. and Davis D. H., “Reduction in permeability with overburden pressure,” J. Petroleum Transactions,” AIME, Vol. 4, Issue12, December 1952.##

[2]. Chen J. H., Kang Y. L., You L. J., and Fang J. W., “Review and prospect about study on stress-sensitivity of low-permeability reservoir,” J. Natural Gas Geoscience, 2011.##

[3]. Davies J. P., and Davies D. K., “Stress-dependent permeability: characterization and modeling,” In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, Jan.1999.##

[4]. Haifeng Z., Jun S., Erfei M., Hang C. and Guohua L. “Scale model of stress sensitivity for fractured low-permeability reservoirs,” Proceedings, Fortieth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, SGP-TR-204, January 26-28, 2015.##

[5]. Lei G., Dong P., Wu Z., Mo S., Gai S., Zhao C., and Liu Z. K., “A fractal model for the stress-dependent permeability and relative permeability in tight sandstones,” Journal of Canadian Petroleum Technology, Vol. 54(01), pp. 36-48, 2015.##

[6]. Ojagbohunmi and Hamoud, M. T., “Coupling of stress dependent relative permeability and reservoir simulation,” Influence of Geomechanical Processes on Relative Permeability,Ph.D. Thesis, University of Alberta, 2012.##

[8]. Oldakowski k. “Stress induced permeability changes of Athabasca oil sands,” M.Sc. Thesis, University of Alberta, Edmonton, Canada, 2009.##

[9]. Lei Q., Xiong W., Yuang J., Cui Y., and Wu Y. S., “Analysis of stress sensitivity and its influence on oil production from tight reservoirs,” In Eastern Regional Meeting. Society of Petroleum Engineers, Jan. 2007. ##

[10]. Jolly R. J. H., Wei L., and Pine R. J., “Stress-sensitive fracture-flow modelling in fractured reservoirs,” In SPE International Petroleum Conference and Exhibition in Mexico. Society of Petroleum Engineers, Jan.2000.##

[11]. قبادی ب.، نجاتی ح. ر. و گشتاسبی ک.، "بررسی عددی رفتار هیدرومکانیکی درزه‎های سنگی منفرد تحت بارگذاری برش مستقیم،" روش های تحلیلی و عددی در مهندسی معدن، 7 (13)، ص 44-35، 1396.#3

[12]. Tao Q., Ehlig-Economides C. A., and Ghassemi A., “Investigation of stress-dependent permeability in naturally fractured reservoirs using a fully Coupled poroelastic displacement discontinuity model,” In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, Jan. 2000. ##

[13]. Tao Q., Ehlig-Economides C. A. and Ghassemi, A., “Modeling variation of stress and permeability in naturally fractured reservoirs using displacement discontinuity method,” In 43rd US Rock Mechanics Symposium & 4th US-Canada Rock Mechanics Symposium. American Rock Mechanics Association, Jan.2000.##

[14]. Zimmerman R. W. and Bodvarsson G. S., “Hydraulic conductivity of rock fractures. Transport in porous media,” Vol. 23, No. 1, pp. 1-30, 1996.##

[15]. Chacon A. “Effect of  pressure depletion on hydrocarbon recovery in naturally fractured reservoirs,” Total Edition Press, Paris, 1987.##

[16]. Wei L. and Hudson J. A., “DEM modelling of water flow in jointed rocks,” 70th International Congress on Rock Mechanics, Aachen, Vol. 1, pp. 823-826, 1991.##

[17]. Saidi A. M., “Reservoir engineering of fractured reservoirs,” Ph.D. Dissertation, The University of Oklahama, Norman, OK, 2006.##

[18]. Snow D T., “Anisotropic permeability of fractured media,” Water Resources Research, Vol. 5, No. 6, pp. 1273–1289, 1968.##

[19]. Raven K. G., and Gale J. E., “Water flow in a natural rock fracture as a function of stress and sample size,” In International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Vol. 22, No. 4, pp. 251-261, Pergamon, Aug. 1985.##

[20]. Brace W., Walsh J. B. and Frangos W. T., “Permeability of granite under high pressure,” Journal of Geophysical research, Vol. 73, No. 6, pp.2225-2236, 1968.##

[21]. Swan G., “Determination of stiffness and other joint properties from roughness measurements,” Rock Mechanics and Rock Engineering, Vol. 16, No. 1, pp. 19-38, 1983.##

[22]. Gale J. E., “The effects of fracture type (induced versus natural) on the stress-fracture closure-fracture permeability relationships,” In The 23rd US Symposium on Rock Mechanics (USRMS). American Rock Mechanics Association, Jan. 1982. ##

[23]. Detournay E., “Hydraulic conductivity of closed rock fracture: an experimental and analytical study,” In Proceedings of the 13th Canadian Rock Mechanics Symposium, pp. 168-173, May 1980.##

[24]. Walsh J. B., Grosenbaugh M. A., “A new model for analyzing the effect of fractures on compressibility,” Journal of Geophysical Research, Vol. 84, (B7): pp. 3532–3536, 1979.##

[25]. Gangi A. F., “Variation of whole and fractured porous rocks permeability with confining pressure,” International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Vol. 15, No. 5, pp. 249–354, 1978.##

[26]. Louis C. A., Dessenne J. L. and Feuga B., “Interaction between water flow phenomena and the mechanical behavior of soil or rock masses,” In: Gudehus G, eds. Finite Elements in Geomechanics, New York: Wiley, pp. 479–511, 1977.##

[27]. Jones F. O., “A laboratory study of the effects of confining pressure on fracture flow and storage capacity in carbonate rocks,” Journal of Petroleum Technology, Vol. 21, pp. 21–27, 1975.##

[28]. Nelson R. “Fracture permeability in porous reservoirs: Experimental and field approach, PhD. Thesist,” Texas: Texas A&M University, 1975. ##

[29]. Tiller F. M., “The role of porosity in filtration: Numerical methods for constant rate and constant pressure n. filtration based on Kozeny’s law,” Chemical Engineering Progress, Vol. 49, No. 9, pp. 467–479, 1953.##

[30]. Raghavan R., and Chin L. Y., “Productivity changes in reservoirs with stress-dependent permeability,” In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, Jan. 2002,.##

[31]. Itasca U D EC., Universal Distinct Element Code. “Version 5.0.,” 2011.##

[32]. Fatehi Marji M., and Arash P., “The effect of fracture orientation and coupled stress-fluid flow on permeability and productivity index of naturally fractured hydrocarbon reservoirs,” In 45th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Associatio, Jan. 2011.##