نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده مهندسی نفت، دانشگاه صنعتی امیرکبیر، تهران، ایران
2 گروه زمین شناسی، دانشکده زمین شناسی، دانشگاه خوارزمی، تهران، ایران
3 دانشکده زمین شناسی، دانشگاه تهران
4 شرکت ملی مناطق نفت‌خیز جنوب
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The study of reservoir quality in carbonates requires a detailed investigation of sedimentology and diagenesis processes. In this paper, the factors controlling the reservoir quality of Asmari-Jahrum formations in the Nargesi oil field in the framework of sequence stratigraphy were evaluated by a comprehensive petrographic study to identify the microfacies and diagenesis processes. By studying 209 microscopic thin sections in the NI-06 well, 14 microfacies were introduced in the sub-environments of the intertidal zone, lagoon, shoal, and middle ramp which have deposited along a homoclinal ramp. Petrographic evidence indicates the occurrence of two diagenesis stages (eogenesis and mesogenesis) and three diagenesis environments (marine, meteoric, and burial) in the paragenesis sequence of the studied formations. The obtained results showed that the dissolution and fracturing processes have increased the reservoir quality, but the compaction, cementation, and anhydritization processes have decreased the reservoir quality in the studied formations. Sequence stratigraphic studies using the Transgressive-Regressive sequence method, investigation of sedimentary characteristics and early diagenesis, and examining the variations of petrophysical logs show six third-order sedimentary sequences in the Asmari-Jahrum formations from the Nargesi field. Also, the rock types (Wineland, Lucia, and Flow Zone Index), sedimentary sequences, diagenetic processes, facies, and petrophysical logs variations imply 8 different zones (e.g., reservoir, speed, and baffle zones) in the Asmari-Jahrum reservoir. The influence of sedimentary microfacies, the diversity of diagenesis processes in each zone and considering their position in the sequences, corroborate the observed changes trend of the reservoir characteristics in the identified zones. In general, the Asmari Formation in zones#1, 2, and 3 (upper part) in the Nargesi oil field has a better reservoir quality than the Jahrum Formation, and this indicates that the diagenesis processes especially fracturing, played a vital role in controlling the reservoir potential of the Asmari Formation. In the Jahrum Formation in Zone 7, mud-dominated microfacies are abundant in the lagoon and middle ramp environments. Dissolution in the form of vuggy porosity, microfracture, and intercrystalline porosity caused by dolomitization has had the most important effect in improving the quality of this reservoir zone.
کلیدواژه‌ها [English]
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