نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زمینشناسی، دانشکده علوم، دانشگاه اصفهان، ایران
2 دانشگاه اصفهان
3 پژوهشگاه صنعت نفت
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In this study, the upper part of the Sarvak Formation (Upper Albian–Cenomanian) in a well from the Abadan Plain oilfields has been analyzed through petrographic and petrophysical methods. Based on thin-section studies of core samples, the Sarvak Formation contains 8 microfacies related to four sub-environments: tidal flat, lagoon, shoal, and open marine, which were deposited within a homoclinal carbonate ramp platform. Diagenetic processes such as reducing neomorphism, bioturbation, cementation, increasing neomorphism, dissolution, mechanical and chemical compaction, dolomitization, silicification, and fracturing during various stages of marine, burial, and partially meteoric diagenesis have affected the reservoir quality of these deposits. Dissolution of matrix and grains with aragonitic shells has improved reservoir quality, whereas pore-lining cementation is identified as the main factor in reservoir quality reduction. Petrophysical evidence indicates the presence of reservoir zones in skeletal grainstone to packstone facies deposited in the high-energy shoal and inner ramp settings. In contrast, mudstone and fine-grained packstones belonging to the lagoon and tidal flat environments show the poorest reservoir quality. SEM images confirm the presence of mainly intergranular and dissolution porosity in reservoir zones, while non-reservoir intervals are characterized by isolated, mostly intragranular pores. Additionally, seven electrofacies were identified based on well-log data. The studied interval was divided into five flow units using the modified Lorenz method based on porosity and permeability derived from well logs. Core-measured porosity and permeability place the studied rock sequence within Lucia’s Class 2 and Class 3 classifications. Pore size estimations using the Winland and Pittman methods indicate that the existing pores are predominantly in the microscopic to mesoscopic range.
کلیدواژهها [English]
)