بررسی تأثیر افزایش فشار منفذی ناشی از تزریق گاز بر پایداری گسل‌های نرمال یکی از میادین جنوب غرب ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه زمین‌شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران

2 گروه زمین‌شناسی، دانشکده علوم پایه، دانشگاه فردوسی مشهد، مشهد، ایران

3 کارشناس ارشد زمین شناسی مهندسی، مناطق نفت خیز جنوب

چکیده

 یکی از مهم‌ترین مسائل مربوط به مخازن نفتی، افت فشار مخزن ناشی از برداشت هیدروکربن‌ها از آن‌ها است. به منظور حفظ میزان تولید یک چاه، انرژی از دست رفته مخزن باید به گونه‌ای جبران شود. یکی از روش‌های افزایش فشار مخزن تزریق گاز طبیعی است که در مخازن جنوب غرب ایران به طور عمده‌ای انجام می‌شود. از جمله مشکلات احتمالی مرتبط با تزریق گاز، ایجاد شکستگی‌های جدید و فعال شدن مجدد گسل‌های از پیش موجود می‌باشد. در این پژوهش با استفاده از روش تحلیلی تمایل لغزش اصلاح شده، امکان فعالیت مجدد چهار گسل موجود در منطقه بررسی و فشار منفذی بحرانی تزریق تخمین زده شده است. نتایج محاسبات تمایل لغزش نشان می‌دهند که تمامی گسل‌ها در شرایط تنش کنونی مخزن پایدار هستند و  گسل F2 پایدارترین گسل پس از تزریق بوده که می‌تواند یک افزایش فشار منفذی تا 57 مگاپاسکال را تا قبل از لغزش بر روی صفحه خود تحمل کند. نتایج تخمین پایداری شکستگی نشان می‌دهد که بیشترین میزان تغییرات تنش افقی لازم برای فعالیت مجدد نیز مرتبط با گسل F2 است که بیانگر پایداری بیشتر گسل‌های دارای امتداد شرقی-غربی نسبت به گسل‌های با امتداد شمال شرق-جنوب غرب در میدان می‌باشد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the effect of pore pressure increase due to gas injection on the stability of normal faults in one of the SW Iranian oil fields

نویسندگان [English]

  • Mohammad Ghafoori 1
  • Majid Taghipour 2
  • Gholam Reza Lashkaripour 1
  • Naser Hafezi Moghaddas 1
  • Abdollah Molaghab 3
1 Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
2 Geology Department, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
3 National Iranian South Oil Company, (NIOSC), Ahwaz, Iran
چکیده [English]

Decreasing reservoir pressure caused by hydrocarbon exploitation is one of the major problems related to oil reservoirs. In order to maintain the current production rate the lost energy should be compensated. Gas injection is a common method for increasing reservoir pressure and is mainly used in SW Iranian oil fields. Reactivation of pre-existing faults is one of the potential risks related to gas injection. In this study, using the analytical method of modified slip tendency, the reactivation possibility of four faults in an SW Iranian oil field has been investigated, and the critical pore pressure is estimated. Results suggest that all the faults are stable in the current stress field, and F2 is the most stable fault that can undergo a maximum pore pressure of 57 MPa before reactivation. Results of fracture stability analysis show that the highest increase in horizontal stress needed for reactivation is for F2. This means that faults with an east-west strike are more stable than the faults with a north east-south west strike in the field.

کلیدواژه‌ها [English]

  • Gas injection
  • Fault stability
  • Geomechanical analysis
  • Slip tendency
  • Asmari Reservoir
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