نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده زمین شناسی، دانشکدگان علوم، دانشگاه تهران، تهران، ایران
2 دانشکده زمینشناسی، دانشکدگان علوم، دانشگاه تهران، تهران، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The Ilam Formation is one of the important hydrocarbon reservoirs in the Abadan Plain. Facies analysis led to the identification of 7 microfacies that were deposited in a range of inner-,, middle- and outer ramp settings. Important diagenetic processes affecting reservoir properties include microscopic dissolution,, dolomitization, compaction, and cementation. The determination of hydraulic flow units based on the flow zone indicator led to the separation of 5 flow units. Using the stratigraphic modified Lorenz method,, the entire studied sequence was separated into 4 reservoir, baffle and barrier zones. Electrical facies were separated using gamma-ray, neutron, sonic, density, effective water saturation and effective porosity logs. Electrofacies were correlated with facies, flow units and sequence stratigraphic positions. The results of the above studies showed that the accumulation of open marine facies (mudstone, wackestone to packstone containing oligostegina and plankton foraminifera) with high amounts (up to 20%) of microscopic porosities creates a zone with suitable reservoir quality in the lower part of the Ilam formation. In this zone, the micro-porosities between the micrite particles along with micro-molds and intra-skeletal pores have led to the creation of a significant storage capacity in the reservoir. The permeability of these facies is often low and they have low flow capacity. This reservoir zone corresponds to the transgressive systems tract of the third-order sedimentary sequence of the Ilam Formation. The middle part of the formation showed poor reservoir quality, and in the upper part, the values of porosity and permeability are improved again. The reason for the increase in reservoir quality in this section is the predominance of high-energy and grain-dominant facies belonging to the Shoal setting along with the occurrence of dissolution in these facies. This zone corresponds to the upper part of the regressive systems tract of the third-order sequence of the Ilam Formation.
کلیدواژهها [English]
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