Abstract
Wadi El-Rayan oil field is located in one of the most prolific basins in the northern part of the Western Desert of Egypt. This field produces oil mainly from Abu-Roash Formation which is differentiated into various members of which Abu Roash G and F Members are the most important. This study aims to investigate the different reservoir properties of the Abu Roash G Member (ARG) and evaluate the potential contribution of Abu Roash F Member (ARF) as a source. The well logging data of 10 wells are utilized mainly for enhancing the petrophysical and the source rock analyses. The standard logging analyses usually used for characterizing the hydrocarbon reservoirs are applied. A mixed clastic and carbonate approach is applied for detecting the lithology. Fluid saturations (water and hydrocarbon) are estimated using clean and shaley modules. Estimation of total organic carbon (TOC) is based on Delta logR method as matched with geochemical and Rock Eval pyrolysis measurements. The deduced petrophysical parameters are represented vertically as reservoir analogs and distributed laterally in a number of property variation maps. The study revealed that Abu Roash G Member is divided into zones, of which the reservoir pay zone (RP zone) attains the best reservoir properties. Ranges of 16.5-52.5 and 3.0-19.5 m and 8-26, 19-26, and 45-73% are given for gross and net pay thicknesses, shale volume, effective porosity, and hydrocarbon saturation, respectively. The lateral distribution maps of the reservoir and source rock parameters showed that net reservoir thickness, hydrocarbon saturation, and TOC content increase toward the central of the study area. The Delta logR overlays revealed that ARF Member is a good source rock which is classified into two overlying zones. The upper zone (ARF-SR1) has fair to good source characteristics, while the lower zone (AFR-SR2) is the main source rock with TOC content range of 2.13 to 4.12%. The Rock Eval and geochemical measurements strongly indicate oil-prone facies with hydrogen indices of 509-705 and S2 yields of 9.42-23.26 mg HC/g. In conclusion, the ARG Member showed good hydrocarbon potentiality and reservoir properties. The organic enrichment of the overlying ARF-SR2 zone offered the main source potentiality. Based on the petrophysical data logs and distribution maps, it is recommended to consider central part of the field for any further hydrocarbon exploration/production activity.