Properties Reservoirs Assessment of Sarvak Formation in Yadavaran Oil Field Based on petrographical and Petrophysical data

Yadavaran oil field is one of the oil fields in Iran which located 130 km west of Ahwaz, at a zero point border with Iraq and in the vicinity of the Hural Hoveyzah wetland, and is located in the Iraqi Majnoon field in a joint oil reservoir. The most important reservoir of this field is the Sarvak Formation (Upper Albian- Turonian) from the Bangestan Group which, together with the Ilam Formation, forms the second major reservoir of Zagros Basin after the Asmari Formation. In order to evaluate the reservoir characteristics of the Sarvak Formation based on petrophysical and petrographical data in Yadavaran oilfield, one well was selected and analyzed. Based on the petrophysical cross plots, Sarvak Formation with the thickness of 640 meters is conformed of limestone. Based on the study of 500 thin sections of the cutting samples and cores, 10 carbonate microfacies were identified that were deposited in a carbonate ramp. Major diagenetic processes affecting the Sarvak Formation include neomorphism, bioturbation, micritization, dissolution, cementation, compaction, piritization, hematitization, and fractures. The main types of porosities identified in Sarvak Formation are vuggy porosity, intercrystaline, molding, and microscopic fractures, which have higher permeabilities than the other porosities detected. The sum of petrographic and petrophysical studies showed that the Sarvak reservoir can be divided into 5 main reservoir zones and 4 sub-reservoir zones (9 in total) in the study area. Zone number 2, sub-zone 4-1, 4-3, and some parts of sub-zone 5-2 have good reservoir quality. Studies also showed that ...