نقش مشخصات رخساره رسوبی در رفتار مکانیکی سنگ، مطالعه موردی در سازند آسماری، جنوب- غرب ایران

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشکده زمین‌شناسی، پردیس علوم پایه، دانشگاه تهران، ایران

2 بخش زمین‌شناسی، شرکت نفت مناطق مرکزی ایران

چکیده

از آنجایی‌که در اکتشاف و تولید نفت به مطالعات ژئومکانیک مخزن توجه ویژه‌ای دارند، در این پژوهش تأثیر رخساره، محیط رسوبی، بافت و دیاژنز بر رفتار ژئومکانیکی سازند آسماری بررسی شده است. داده‌های استفاده شده شامل 1) داده‌های رسوب‌شناسی مانند پتروگرافی مقطع نازک، تخلخل و چگالی؛ 2) داده‌های مکانیک سنگ مانند مقاوت تراکمی تک‌محوری و سه‌محرری سنگ، ضریب چسبندگی و زاویه اصطکاک داخلی سنگ، مقاومت کششی سنگ و اندیس شکستگی و حفاری؛ 3) داده‌های سرعت موج S و P. که برروی 140 عدد مغزه رخنمون و چاه انجام شدند. به‌منظور مطالعه رابطه ممکن بین خصوصیات رسوب‌شناسی و مکانیکی سنگی، خصوصیات رسوب شناسی با اندیس رخساره براساس ویژگی‌های بافتی و دیاژنزی رقومی شده‌اند. براساس اندیس رخساره، مقدار تخلخل و مقاومت تراکمی تک محوری سنگ پنج رخساره ژئومکانیکی در سازند آسماری مشخص شد که از رخساره ژئومکانیکی 1 تا 5 از رفتار شکل‌پذیر به شکننده تبدیل می‌شوند. نتایج این مطالعه نشان می‌دهد که رفتار مکانیکی سنگ توسط محیط رسوبی و فرآیندهای دیاژنزی کنترل می‌شود که با رقومی کردن خصوصیات رسوب‌شناسی و ایجاد ارتباط با پارامترهای مکانیک سنگی امکان پیش‌بینی مقاومت تراکمی تک محوری سنگ با استفاده از پتروگرافی ایجاد شده است. چنین مطالعاتی کمک موثری در کاهش وقت و هزینه آزمایشات مکانیک سنگ و همچنین در منطقه‌بندی مکانیکی- چینه‌ای مخزن دارد.
 

کلیدواژه‌ها


عنوان مقاله [English]

Role of Sedimentary Microfacies Characteristics in Rock Mechanical Behavior, a Case Study in Asmari Formation, SW Iran

نویسندگان [English]

  • Sajjad Gharechelou 1
  • Abdolhossein Amini 1
  • Mozhdeh Shirazi 1
  • Abbasali Nikandish 2
  • Vahid Farajpour 2
1 Department of Geology, College of Science, University of Tehran, Iran
2 Division of Geology, Iranian Central Oilfields Company, Iran
چکیده [English]

Nowadays, geomechanical studies in hydrocarbon reservoirs are interesting; therefore, the objective of this paper is to investigate the impact of facies, texture and diagenesis on the geomechanical behavior of the Asmari Formation. Three sets of data were used in this research: 1) sedimentological data including thin section petrography, porosity and density, 2) rock mechanical data comprising (1) uniaxial compressive strength, (2) cohesion, (3) friction angle, (4) tensile strength, and (5) brittleness and drillability indexes, and 3) ultrasonic data including S- and P-wave velocities. To investigate a possible relationship between the sedimentological features and rock mechanical behaviors, a facies index was defined based on the textural and diagenetic features allowing to quantify a sedimentary microfacies. Based on facies index, porosity and UCS five different geomechanical facies were determined for the Asmari Formation, where GMF1 to GMF5 represent very ductile to very brittle behavior respectively. Finally, the results of the study showed that mechanical behavior is controlled by the depositional and diagenetic overprints. Furthermore, by facies index, the rock strength may be predicted based on petrographical observations. Such studies are helpful for reducing the costs/time for acquiring geomechanical datasets and zoning mechanical stratigraphy.
 

کلیدواژه‌ها [English]

  • Geomechanical Units
  • Asmari Formation
  • uniaxial compressive strength
  • facies index
  • Geomechanical Tacies
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