Facies and petrophysical modeling of the Upper Bahariya Member in Abu Gharadig oil and gas field, north Western Desert, Egypt

Abstract

The Upper Bahariya Member represents an argillaceous sandstone reservoir and it is one the Late Cretaceous units. There is a need for understanding the detailed facies and petrophysics of this member and identifying whether its petrophysical parameters are related to the facies changes or the present structures. Therefore, the present study aims at determining the facies and petrophysical characteristics of the Upper Bahariya Member and their distribution in the Abu Gharadig field. This field is located in the central portion of Abu Gharadig basin in the northern part of the Western Desert of Egypt. The available data for the present study includes four digital well logs, twenty 2D seismic sections and a checkshot survey. This is achieved through building the 3D facies and petrophysical models using Petrel™ Schlumberger Modeling software. These models were built on a predefined 3D stratigraphic and structural framework. The interpreted lithology of the Upper Bahariya Member is represented by sandstone cemented by argillaceous and/or calcareous materials, siltstone, shale and minor limestone inter-beds. A new lithofacies subdivision for the Upper Bahariya is introduced in the present study through the study area. This subdivision is represented by three lithofacies (an upper shale-silt-carbonate lithofacies, a middle sand-silt lithofacies and a lower shale-silt lithofacies). The Upper Bahariya Member is evaluated as a good quality reservoir and it exhibits rapid variations in the conditions of deposition, from continental fluvial to marine passing through the tidal flood plain conditions. The sandstone source is mainly from the southeast and southwest directions. The vertical and lateral changes of the different petrophysical parameters are directly related to vertical and lateral facies changes.