Petrophysical analysis of early cretaceous Saar carbonates from Sharyoof oilfield in the Masila Basin, eastern Yemen, and their impact on reservoir properties and quality

The Saar Formation, the late Early Cretaceous in age, is a secondary reservoir rock containing low amounts of proven oil in the Sharyoof oilfield, Masila Basin. The lithofacies of the Saar Formation at Sharyoof oilfield is mainly composed of dolomite and dolomitic limestone with limestone intercalations, reflecting a marine setting. Petrophysical properties and some petrographic characteristics were used to evaluate the reservoir characteristics and quality of the Saar carbonates. Generally, the Saar carbonates have poor to good reservoir quality. The porosity ranges from 6 to 21 %, and permeability varies from 0.01 to 500 md. The pore types are secondary pores in form vugs and fractures as identified under microscope. The good reservoir quality of the Saar carbonates is characterized by a relatively high secondary porosity and permeability. Therefore, the dolomite and dolomitic limestone intervals of the Saar Formation have good reservoir quality and reveal promising reservoir characteristics, which should be taken into consideration during future development of the Sharyoof oilfield. The Saar carbonates have hydrocarbon saturation exceeding 70 %, with low oil movability, indicating high residual oil saturation and the production is mainly water with limited oil.