مدلسازی فیزیکی و مطالعه آزمایشگاهی تأثیر رژیم تنش ها بر شکست هیدرولیکی

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی معدن، دانشگاه صنعتی سهند تبریز، تبریز، ایران

چکیده

شکست هیدرولیکی، یکی از مهم ترین روش های تحریک مخازن نفت و گاز می باشد که برای افزایش جریان سیال از مخازن با تراوایی پایین به سمت چاه استفاده می شود. عوامل مختلفی، همچون رژیم تنش ها، درزه ها و شکستگی های طبیعی سازند، رئولوژی سیال، خواص مکانیکی سازند، شدت جریان سیال تزریقی و مشبک کاری بر روی فشار و هندسه شکست هیدرولیکی تأثیرگذار هستند. در این تحقیق، برای بررسی آزمایشگاهی تأثیر رژیم تنش ها بر شکست هیدرولیکی، با در نظر گرفتن شرایط مخزن، دستگاه سه محوره ای طراحی و ساخته شد. این دستگاه، توانایی اعمال تنش های ناهمسانگرد برجای زمین در مقیاس آزمایشگاهی را دارا می باشد. سپس 32 نمونه مکعبی سیمانی با ابعاد 10×10×10 سانتیمتر ساخته شد و تأثیر رژیم تنش ها، بر روی هندسه و فشار شکست هیدرولیکی، نمودار فشار-زمان و نحوه گسترش ریز ترک ها و شکستگی های متقاطع در دو حالت چاه قائم و افقی بررسی شد. نتایج مطالعات آزمایشگاهی نشان داد، با افزایش تنش افقی حداکثر در چاه قائم، فشار شکست، یک روند افزایشی- کاهشی و در چاه افقی، فشار شکست، یک روند تقریباً کاهشی را نشان می دهد. در چاه قائم، تأثیر تنش افقی حداکثر بر روی فشار شکست، بیشتر از تنش قائم است، در حالی که در چاه افقی، تأثیر تنش قائم، بیشتر از تنش افقی است. همچنین، با کاهش تنش تفاضلی افقی، در هر دو چاه قائم و افقی، ریز ترک ها و ترک های شاخه ای کوتاه بیشتر می شود. بررسی های آزمایشگاهی این تحقیق با استفاده از مواد شبه سنگی، رفتار مواد سنگی مطالعات قبلی را تأیید می کند.

کلیدواژه‌ها


عنوان مقاله [English]

A laboratory study of the effects of stress regimes on hydraulic fracturing

نویسندگان [English]

  • Mohammad Darbor
  • Hadi Shakeri
Mining Engineering Faculty, Sahand University of Technology, Tabriz, Iran
چکیده [English]

Hydraulic fracturing is one of the most important stimulation methods for oil and gas reservoirs to increase fluid flow from low permeability reservoirs to wellbores. Various factors, such as in-situ stresses, joints and natural fractures of the formation, fluid rheology, mechanical properties of the formation, injection fluid flow rate and perforation operation, effect on the pressure and hydraulic fracture geometry. In this research, for the experimental investigation of the hydraulic fracturing, considering the reservoir condition, a three-axial machine with the ability to apply the main stresses was designed and built. Then, 32 concrete cubic samples with 10 × 10 × 10 cm dimensions were constructed and cured in the laboratory and the effect of the in-situ stress field and stress regime on the geometry and breakdown pressure, the pressure-time diagram, the pattern of crack propagation and finally the cross fractures in both vertical and horizontal wellbores were investigated. The results showed that increasing the maximum horizontal stress in the vertical wellbore leads to increased breakdown pressure and increasing deviatoric stress in the horizontal wellbore reduces the breakdown pressure.

کلیدواژه‌ها [English]

  • Physical modelling
  • hydraulic fracturing
  • stress regime
  • breakdown pressure
  • fracture geometry
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