بررسی مکانیسم هرزروی گل حفاری برای چاه قائم در سازند دارای شکستگی با در نظر گیری شرایط تخلخل دوگانه: مطالعه موردی چاه SIE-05 در حوزه نفتی خلیج‌فارس

نوع مقاله : مقاله پژوهشی

نویسندگان

1 معدن، مکانیک سنگ، صنعتی امیر کبیر، تهران، ایران

2 اداره زمین شناسی، شرکت نفت فلات قاره، تهران، ایران

3 دکتری ژئومکانیک، دانشگاه ارومیه

چکیده

حفاری در سازندهای دارای شکستگی و مسئله هرزروی سیال یکی از چالش‌های مهم در صنایع بالادستی نفت است. ناپایداری چاه، زمان‌های غیر مولد(NPT)، هرزروی سیال حفاری و مخاطرات ناشی از آن می‌تواند منجر به افزایش هزینه‌های حفاری شود. کنترل و مدیریت فشار حفاری (MPD) ازجمله ابزارهای مؤثر در کاهش هزینه‌های حفاری است. وجود شکستگی‌های طبیعی و پیچیدگی فرآیندهای هیدرومکانیکی در این سازندها، مسئله کنترل فشار ته چاه و تعیین مشخصه‌های بهینه گل حفاری را دشوار می‌کند. بنابراین برای تعیین یک الگوی حفاری بهینه، شناخت مکانیسم‌های هیدرومکانیکی ضروری است. در این مقاله با ایجاد مدل سه‌بعدی هیدرومکانیکی از چاه در سازند دارای شکستگی و با در نظر گرفتن شرایط تخلخل دوگانه، هرزروی سیال در ماتریکس و شکستگی بررسی‌شده است. نتایج نشان داد با افزایش نرخ تزریق سیال حفاری جابجایی‌های برشی در امتداد شکستگی افزایش و افت فشار سیال مشاهده شد. برای نرخ تزریق 10 بشکه بر ساعت سهم ماتریکس تراوا و شکستگی در هرزروی سیال برابر به دست آمد. در شرایط تنش‌های همسانگرد لغزش‌ها در امتداد شکستگی محدود و درنتیجه فشار سیال افزایش یافت. با افزایش نسبت تنش‌های افقی بیشینه به کمینه گسترش سیال در امتداد شکستگی‌ها افزایش و سهم تراوش سیال از فصل مشترک صفحات شکستگی و ماتریکس سنگی مجاور آن افزایش می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of mud loss mechanism for vertical wellbore in fractures formation considering dual porosity conditions: A case study for SIE-05 wellbore in Persian Gulf oilfield

نویسندگان [English]

  • mohammad komeilian 1
  • Mahdi Rahbar 2
  • Omid Saeidi 3
1 Department of Mining & Metallurgical Engineering
2 Geology Department, Iranian Offshore Oil Company, Tehran, Iran
3 Geomechanic Ph.D., University of Urmia
چکیده [English]

Wellbore instability and drilling fluid loss in fracture formation is one of the main issues in deep drilling. In order to determine an efficient drilling methodology it is necessary to investigate the effect of fracture on instability and fluid loss mechanism. In this article in order to evaluation of the vertical wellbore stability and fluid loss in fracture formation, three dimensional simulation of a wellbore in the Persian Gulf was carried out using Discrete Fracture Network (DFN) and Distinct Element Method (DEM). In order to investigate the Hydromechanical mechanism in fracture formation, drilling fluid was injected by rate of 10 BPH and viscosity of 1.08 cP to the wellbore. Slip in fractures, shear displacement and the volume of fluid loss was determined as main parameters for wellbore stability analysis. The effect of in-situ stresses ratio (σ_H/σ_h ) on instability mechanism and fluid loss was carried out based on 4 different scenarios for in-situ stresses ratio. By increasing in-situ stresses ratio and in an anisotropic (σ_H/σ_h =2) satat, slips and shear displacement along the discontinuity increased. In this case, for 25 BPH drilling fluid flow ratio the fluid pressure decrease along the discontinuities. The parametric study for five different fluid flow ratio showed that in (σ_H/σ_h =1.06) the fluid expansion in fracture increased. Moreover, tension failure and shear displacement decreased in low fluid flow ratio. In 5 BPH fluid flow ratio, the fluid pressure in fractures increased compared with higher fluid flow ratio. This is because of less shear displacement and fluid expansion along fracture in lower fluid flow ratio.

کلیدواژه‌ها [English]

  • Natural fractures
  • Drilling fluid loss
  • Distinct element method
  • Hydromechanical modeling
  • Double porosity
  • Stress dependent permeability
Abdideh, M. a. (2013). Estimating the reservoir permeability and fracture density using petrophysical logs in Marun oil field (SW Iran). Petroleum Science and Technology, 1048-1056.
Almagro, S. P. (2014). Sealing fractures: Advances in lost circulation control treatments. Oilfield Review, 4-13. Retrieved from Schlumberger .
Baecher, G. B. (1983). Statistical analysis of rock mass fracturing. Journal of the International Association for Mathematical Geology, 329-348.
Bour, O. a. (2002). A statistical scaling model for fracture network geometry, with validation on a multiscale mapping of a joint network (Hornelen Basin, Norway). Journal of Geophysical Research: Solid Earth, ETG-4.
Cao, N. a. (2019). Stress-Dependent Permeability of Fractures in Tight Reservoirs. Energies, 117.
Cappa, F. a.-F. (2006). Hydromechanical modelling of pulse tests that measure fluid pressure and fracture normal displacement at the Coaraze Laboratory site, France. International Journal of Rock Mechanics and Mining Sciences, 1062-1082.
Halliburton . (2018). Retrieved from Halliburton : https://www.halliburton.com/en-US/default.html Han, G. a. (2003). Description of fluid flow around a wellbore with stress-dependent porosity and permeability. Journal of Petroleum science and engineering, 1-16.
Hart, R. (2003). Enhancing rock stress understanding through numerical analysis. International journal of rock mechanics and mining sciences, 1089-1097.
Itasca. (2016). 3DEC User Manual Version 5.2. Minneapolis: Itasca Consulting Group.
Karatela, E. a. (2016). Study on effect of in-situ stress ratio and discontinuities orientation on borehole stability in heavily fractured rocks using discrete element method. Journal of Petroleum Science and Engineering, 139, 94–103.
Labenski, F. a. (2003). Drilling Fluids Approaches for Control of Wellbore Instability in Fractured Formations. SPE/IADC Middle East Drilling Technology Conference and Exhibition. Abu Dhabi: Society of Petroleum Engineers.
Lei, Q. a.-P.-F. (2017). The use of discrete fracture networks for modelling coupled geomechanical and hydrological behaviour of fractured rocks. Computers and Geotechnics, 151-176.
Li, S. a. (2012). Pore-pressure and wellbore-stability prediction to increase drilling efficiency. Journal of Petroleum Technology, 64, 98-101.
Mansour, A. a. (2019). Smart lost circulation materials for productive zones. Journal of Petroleum Exploration and Production Technology, 281-296.
Meng, M. a. (2019). Wellbore stability in naturally fractured formations featuring dual-porosity/singlepermeability and finite radial fluid discharge. Journal of Petroleum Science and Engineering, 790-803.
Min, K.-B. a.-F. (2004). Stress-dependent permeability of fractured rock masses: a numerical study. International Journal of Rock Mechanics and Mining Sciences, 1191-1210.
Nagel, N. a.-N. (2013). Coupled numerical evaluations of the geomechanical interactions between a hydraulic fracture stimulation and a natural fracture system in shale formations. Rock mechanics and rock engineering, 581-609.
Salehi, S. a. (2010). Numerical simulations of wellbore stability in under-balanced-drilling wells. Journal of Petroleum Science and Engineering, 229-235.
Sapigni, M. a. (2003). Engineering geological characterization and comparison of predicted and measured performance of a cavern in the Italian Alps. Engineering geology, 47-62.
Taheri, A. (2018). Three-dimensional hydro-mechanical model of borehole in fractured rock mass using discrete element method. Journal of Natural Gas Science and Engineering, 53 , 263–275.
Tour, J. M. (2012). Graphene compositions and drilling fluids derived therefrom. United States Patent and Trademark Office.
Valenti, N. P. (2002). A unified theory on residual oil s aturation and irreducible water saturation. SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers.
Zhang, J. (2013). Borehole stability analysis accounting for anisotropies in drilling to weak bedding planes. International journal of rock mechanics and mining sciences, 160-170.
Zhang, X. a. (1999). Numerical modelling of wellbore behaviour in fractured rock masses. Journal of Petroleum Science and Engineering, 95-115.
Zhang, Z. a. (2018). Effects of stress-dependent permeability on well performance of ultra-low permeability oil reservoir in China. Journal of Petroleum Exploration and Production Technology, 565-575.