Authors
1
Head of sedimentary basin and petroleum department, faculty of earth sciences, Shahid beheshti university, tehran, iran
2
National Iranian Oil Company, Exploration Directorate
3
Petroleum and Sedimentary Basin Group, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
4
Department of Sedimentary Basin and Petroleum, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
Abstract
The Sarvak carbonate Formation is an important formation in the Zagros region, known as the second largest oil reserve, after the Asmari Formation. This study focused on studying two oil wells of the Sarvak Formation in the Dezful Embayment, which is from the Late Albian-Early Turonian. The lower boundary of this formation is undetermined as a result of the incomplete drilling of wells, and it changes into the Surgah Formation at the upper border. Examination of thin sections of cuttings samples indicates the development of microfacies within this formation in the platform settings of a lagoon, barrier, and open marine in an inner, middle, and outer carbonate platform. According to this study, the Sarvak Formation consists of four 3rd-order depositional sequences, labeled A, B, C, and D, which correlated with its equivalent in the Arabian plate. Except for depositional sequence A in the examined oil fields, included part of highstand system tract (HST), in result of incomplete well drilling, the other depositional sequences consist of transgressive system tract (TST) and highstand system tract (HST). Based on the two-dimensional panel obtained from the analyzed fields in the research area, it can be observed that the process of facies changes and subsequent formation of depositional facies settings prograde from the X oil field toward the Y oil field. Additionally, the thickness of this depositional sequence in compared to the other sequences is the lowest. According to the research, the sedimentary basin of the Sarvak Formation during the formation of the final sequence (i.e., depositional sequence D) includes deeper microfacies compared to other sequences. The main diagenesis processes examined in the thin sections microscopy of this formation include cementation: syntaxial overgrowth rime, equant, drusy, blocky, poikilotopic. The other diagenetic processes in this formation are: dissolution, bioturbations (boring and barrowing), micritization, compaction, pyritization, porosity, and dolomitization.
Keywords
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