رسائل ماجيستير
English
2024
Reservoir characterization of fluvial systems: a case study from the middle and upper members of the Permian Gharif Formation (Asfoor field, Central Oman)
Mohamed Ali K. El-Ghali, Muthanna Masoud Al-Mughairi , Iftikhar Ahmed Abbasi
كلية العلوم-جامعة السلطان قابوس · عمان
This project aims to study and characterize the fluvial sequence of the Middle and Upper Gharif Formation in the Asfoor field, located in central Oman. The Gharif Formation is one of the most prolific hydrocarbon reservoirs in the Sultanate of Oman and serves as a key target for extensive exploration and production activities.
The study focuses on understanding the reservoir architecture, depositional environments, and reservoir quality of the middle and upper members of the Gharif Formation, specifically Middle Gharif 1 (MG1), Middle Gharif 2 (MG2), Upper Gharif 3 (UG3), and Upper Gharif 4 (UG4) within the Asfoor field.
A well correlation analysis was conducted on 53 wells using Petrel (2020) software across all Gharif units. Paleogeographic maps, highlighting channel fairways of the Gharif subunits, were developed using log signature analysis, petrophysical facies logs, and paleocurrent data. These maps were integrated with reservoir descriptions and “plumbing diagrams” to build depositional scenarios linked to the paleogeographic reconstructions. Based on this integration, a conceptual depositional model for the Middle and Upper Gharif was established.
Reservoir quality evaluation for the Middle Gharif units utilized core and petrophysical data, which was correlated with the paleogeographic and depositional findings.
Key depositional interpretations from the well correlations indicate that MG3 was deposited in a shoreface environment, whereas MG2 and MG1 formed in a fluvial setting dominated by ephemeral channels and sheetflood deposits, characteristic of an arid to semi-arid climate. UG4 was deposited above an erosional surface, resulting in compensational stacking within a meandering fluvial system, while UG3 accumulated in a classic high-sinuosity meandering fluvial system associated with a humid or tropical climate.
Paleogeographic maps of MG1 and MG2 show two main channel belt orientations trending northwest-southeast (NW-SE) and northeast-southwest (NE-SW), with relatively wide channel belts. Conversely, UG3 and UG4 display channel belts oriented predominantly NE-SW, consistent with regional structural trends.
The lithology of MG1 in the Asfoor field consists primarily of arkosic to subarkosic sandstones, whereas MG2 is dominated by litharenitic to sublitharenitic sandstones. The reservoir quality of MG1 is notably affected by clay mineral infiltration occurring just below an erosional surface. In contrast, MG2’s reservoir quality is governed by rock fabric and compaction processes.
Overall, the spatial distribution of reservoir properties in the Asfoor field closely follows the paleogeographic patterns identified for these units.