اثر بارگذاری هیدرواستاتیک بر خواص پتروفیزیکی، ژئومکانیکی و ساختاری سنگ مخزن کربناته

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی معدن، پردیس دانشکده‌های فنی، دانشگاه تهران، ایران

2 پردیس پژوهش و توسعه صنایع بالادستی نفت، پژوهشگاه صنعت نفت، ایران

3 گروه مهندسی معدن و نفت دانشگاه نظربایف، آستانا، قزاقستان

چکیده

حین تولید از مخازن هیدروکربنی و فرآیند تزریق، تغییرات فشار منفذی باعث تراکم مخزن می‌گردد که منجر به اثرگذاری مستقیم روی خواص پتروفیزیکی سنگ مخزن می‌شود. بنابراین، شناخت تغییرات رفتار سنگ و خواص مخزنی وابسته به تنش مانند تخلخل و نفوذپذیری بسیار با اهمیت است. در این مطالعه، تلاش می‌شود اثر بارگذاری هیدرواستاتیک بر خواص پتروفیزیکی، ژئومکانیکی و ساختاری سنگ مخزن کربناته بررسی شده و تغییرات تخلخل، نفوذپذیری و توزیع اندازه حفرات مورد تجزیه و تحلیل قرار گیرند. جهت بررسی تغییرات صورت گرفته در رفتار ژئومکانیکی سنگ مخزن کربناته، سرعت موج برشی و تراکمی دو نمونه سنگ مخزن با خواص ظاهری و فیزیکی مشابه تحت بارهای مختلف اندازه‌گیری شد. همچنین، به‌منظور بررسی ساختار و تغییرات داخلی نمونه‌های سنگ مخزن از تصاویر میکروسکوپ الکترونی روبشی (SEM) استفاده شد. نتایج حاصل از این مطالعه حاکی از آن است که با افزایش بارگذاری، نفوذپذیری و تخلخل در آخرین مرحله بارگذاری به‌ترتیب 14/36% و 39/7% روند کاهشی از خود نشان می‌دهند. بررسی سرعت‌های موج برشی و تراکمی نشان دادند که با افزایش فشار آنها روند افزایشی داشته و این مسئله ناشی از میزان نسبت حجم فضای ماتریکس سنگ به فضای خالی آن است. تلفیق آنالیز تصاویر SEM و تغییرات اندازه حفرات نشان می‌دهد که در اثر بارگذاری، حفرات ریزتر و متراکم‌تر گشته و میانگین اندازه دانه‌ها کوچک‌تر می‌گردد، که این خردشدن و قرارگیری ذرات ریزتر در میان ذرات درشت‌تر میزان تخلخل و تراوایی را کاهش می‌دهد. شناخت روند تغییرات خواص پتروفیزیکی به‌همراه بررسی تغییرات ساختاری و ژئومکانیکی متناظر آنها در استراتژی‌های تولید از مخازن نفتی و فرآیندهای تخلیه سیالات از مخازن از اهمیت به‌سزایی برخوردار هستند.
 

کلیدواژه‌ها


عنوان مقاله [English]

Effect of Hydrostatic Stress Loading on Petrophysical, Geomechanical and Structural Properties of Carbonate Reservoir Rock

نویسندگان [English]

  • Yaser Salimidelshad 1
  • Ali Moradzadeh 1
  • Ezzatallah Kazemzadeh 2
  • Peyman Pourafshary 3
  • Abbas Majdi 1
1 School of Mining Engineering, College of Engineering, University of Tehran, Iran
2 Upstream Research Center of Petroleum Industry, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
3 epartment of Petroleum Engineering, School of Mining and Geosciences, Nazarbayev University, Astana, Kazakhstan
چکیده [English]

During the production of hydrocarbon reservoirs and the injection process, pore pressure changes lead to reservoir compaction, which directly affects the petrophysical properties of the reservoir rock. Therefore, it is very important to recognize the changes in rock behavior and reservoir properties such as porosity and permeability which are significant. In this study, the effect of hydrostatic loading on petrophysical, geomechanical and structural properties of carbonate reservoir is investigated, which the investigation is followed by analyzing the porosity, permeability and pore size distribution. In order to investigate the changes in the geomechanical behavior of the carbonate reservoir, the compressional and shear wave velocities of two reservoir rock samples with similar geometrical and physical properties have been measured under different loading conditions. Scanning electron microscopy (SEM) images have also been used to examine the structural changes of rock samples. The results of this study show that under loading, permeability and porosity have a decreasing trend in 36.14% and 7.39% respectively in the last loading step. The study of compressional and shear wave velocities demonstrate that there is an increasing trend by increasing pressure, which it is due to the volume ratio of rock matrix to pore space. Combining the analysis of SEM images and pore size distribution shows that pores have become compacted, and the mean pore size has been reduced, in which this pore collapse and the placement of smaller particles among coarse particles have decreased porosity and permeability. Ultimately, understanding the changes in petrophysical properties along with their corresponding structural and geomechanical changes is very important in production planning of hydrocarbon reservoirs.
 

کلیدواژه‌ها [English]

  • Hydrostatic loading
  • Geomechanical properties
  • Carbonate reservoir rock
  • Microscopic Analysis
  • Sonic Wave Velocity
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