بررسی آزمایشگاهی اثر شرایط تنش‌های اعمال‌شده بر روی نحوه شکست دیواره چاه‌های نفت

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، مهندسی استخراج معدن، دانشگاه بین­المللی امام خمینی قزوین (ره)

2 دانشیار گروه مهندسی معدن، دانشگاه بین­المللی امام خمینی قزوین (ره)

چکیده

حفر چاه در صنایع مختلف مانند نفت، گاز و معدن همواره با مشکل ناپایداری مواجه بوده و نیاز به‌ صرف هزینه­های زیاد دارد. با کنترل تغییر شکل و شکست در دیواره­ی چاه می­توان به حداقل ممکن ناپایداری رسید. در این مقاله، برای بررسی تغییرشکل و نحوه­ی شکست در دیواره­ی چاه­های نفت، مطالعات آزمایشگاهی به وسیله سلول هوک اصلاح ­شده بر روی نمونه­های استوانه­ای توخالی جدار ضخیم ماسه­سنگ، مارن و آهک­رسی انجام شده است. شرایط تنش اعمال ­شده از مهمترین عوامل در تغییر شکل و نحوه­ی شکست در دیواره چاه است. بنابراین شرایط تنش در دو حالت: در حالت اول تنش محوری ثابت و تنش جانبی متغیر و در حالت دوم تنش جانبی ثابت و تنش محوری متغیر، اعمال شد. نتایج آزمایش­­های انجام شده نشان داد که نحوه­ی شکست و تغییر شکل به شدت وابسته به‌ اندازه و جهت تنش­های اعمال­ شده در دیواره­ی چاه است. نحوه­ی شکست برای نمونه­های ماسه­سنگ و آهک­رسی در دیواره چاه طی شرایط تنش محوری ثابت و تنش جانبی متغیر به­صورت پوسته‌پوسته شدن به سمت داخل گمانه است. در حالت تنش جانبی ثابت و تنش محوری متغیر، نحوه­ی شکست در نمونه­های آهک­رسی و مارن با توزیع تصادفی در سه نقطه از روی دیواره­ی چاه که با یکدیگر زاویه 120 درجه می‌سازند، اتفاق می­افتد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental investigation of effect of applied stresses condition on shape of failure in wall of oil wells

نویسندگان [English]

  • Sonya Aghaei 1
  • Mahdi Hosseini 2
1 MSc Student, Department of Mining Engineering, Imam Khomeini International University, Ghazvin, Iran
2 Assistant Professor, Department of Mining Engineering, Imam Khomeini International University, Ghazvin, Iran,
چکیده [English]

The wells drilling in various industries such as oil, gas and mining have always been faced with the instability problem and the solving this need to spend a lot of money. The instability of wall of wellbore can be minimized by controlling deformation and failure. In this paper, experimental investigation has been carried out in two different stress conditions on thick-walled hollow cylindrical samples of sandstone, argillaceous limestone and marl using modified Hoek’s cell to predict the deformation and shape of failure in the wall of wellbore.
In the first series of tests, axial stress is constant and confining stress is changing and the second series of tests condition is vice versa. Experimental results indicated that, the deformation and shape of failure strongly depends upon the magnitude and direction of the imposed stress in the wall of well. Also result illustrated that, under constant axial stress condition, the wall of well, for both sandstone and argillaceous limestone specimens, broke out toward inside the wall of wellbore. Under the constant confining stress condition for argillaceous limestone as well as marl specimens, the failure occurred with random distribution in three points, which meet at 120 degrees

کلیدواژه‌ها [English]

  • Well instabilit
  • Hoek’s cell
  • deformation
  • Failure shape
  • Thick-walled hollow cylinder specimens

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