Assessment of petrophysical parameters of clastics using well logs: The Upper Miocene in El-Wastani gas field, onshore Nile Delta, Egypt

Abstract

Based on logs of ten wells in the El-Wastani gas field, onshore Nile Delta, Egypt, petrophysical evaluation for the Upper-Miocene Qawasim Formation and Abu Madi Formation in the El-Wastani gas field was accomplished. The lithology of these formations was analyzed using cross plots of logging parameters, and petrophysical parameters including shale volume, porosity, water saturation and hydrocarbon pore volume were assessed. The Neutron/Density, Neutron/Gamma-ray and Litho-saturation cross plots of the wells show that the main lithology of the Lower Abu Madi unit is sandstone with shale intercalations, while the lithology of the Qawasim Formation is mainly composed of shale with sandstone intercalations. The cut-offs of shale volume, porosity and water saturation for productive hydrocarbon pay zones are 50%, 10% and 70%, respectively, which were got based on cross-plots and Gamma-ray log data. Contour maps for parameters such as net pay thickness, average porosity, shale volume and water saturation were prepared and it is found out that the Abu Madi Formation and Qawasim Formation in the study area have promising reservoir characteristics; A prospective region for gas accumulation trends northwest-southeast in the study area, especially favorable in the central part. Key words: well log, petrophysical parameter, Upper Miocene, El-Wastani gas field, Nile Delta, Egypt