Petrophysical Evaluation and Geochemical Characterization of Abu Roash F Member Abu Gharadig Basin, Western Desert, Egypt

Abstract

Abu Roash F Member (ARF) is a carbonate formation extended all over the Western Desert in Egypt, ARF has good lateral continuity in all western desert basins but has very poor connectivity and very low permeability. it can be considered as an example of unconventional reservoir. This work aims to evaluate the reservoir quality of Abu Roash "F" Member and compare with the unconventional play commercial developed all over the world. in this study, the key parameters to define reservoir quality; include mineralogy, porosity, water saturation, permeability, organic matter content, Kerogen type and thermal maturity has been investigated. More than 30 Rock-Eval pyrolysis samples from different fields where ARF at significantly different level has been used to evaluate and understand ARF geochemical reservoir quality. On the other side, core and well log data from different fields at different level has been inspected and integrated to evaluate ARF mineralogy, porosity, permeability, water saturation, and identify Potential sweet spots. The results of Rock-Eval analysis show that most of the investigated samples have the total organic carbon content (TOC) values between 1.6 and 6.63 wt% indicating good to very good source rocks and the pyrolysis Yield (PY) ranged from 6 to 20 indicating good to very good potential generation. Based on Tmax and Hydrogen index (HI), the deepest well samples have Tmax values in the range of 435 and 441°C and Hydrogen index (HI) values in the range of 311 to 570 indicating that the organic matter has reached the early to intermediate stages of thermal maturity with dominate kerogen type I-II. While the shallower well samples have Tmax values in the range of 421 and 430°C and Hydrogen index (HI) values in the range of 127 to 687 indicating that the organic matter immature with mixed kerogen type II-III. Petrophysical results supporting that ARF is a carbonate rock deposit under marine conditions and has mixed layer clay (montomonlionite, Kolonite and illite). Numerous techniques to estimate ARF permeability from wireline logs have been investigated, using the available core data porosity permeability relationship has been established. Moreover, the results of petrophysical analysis indicate that Lucia class 3 permeability has good math with core permeability. So, Lucia class 3 permeability can be used to estimate ARF permeability using the calculated effective porosity from well log data. Generally, the results of geochemical and petrophysical evaluation of this study show that ARF has very good reservoir quality comparing with the most of commercially developed unconventional resources all over the world. Moreover, the results show that ARF has a similarity with Eagle Ford Shale in terms of Age, mineralogy, pressure, depth, thickness, and TOC which reflect the potentiality of ARF commercial development.