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Unconventional Shale Gas Sweet Spot Identification and Characterization of the Middle Jurassic Upper Safa Sediments, Amoun Field, Shushan Basin, Western Desert, Egypt

Mohammad Ahmad Elsaqqa*, Mahmoud Yousry Zein El Din, Waleed Afify

The process of pinpointing unconventional shale gas sweet spots demands an extensive analysis of various geological, geochemical, petrophysical, and geomechanical factors. The Amoun field, which is a vital oil and gas reserve in the northern Western Desert of Egypt's Shushan Basin, was examined in this research, specifically targeting the Upper Safa shale as a potential shale gas reservoir. The geological investigation revealed that the Middle Jurassic Upper Safa member was found at a depth range of 12,036 to 12,065 ft. The gross thickness is approximately 602-790 ft., with an average of 696 ft. The potential shale gas sweet spot of the entire Upper Safa member has a net thickness range of 132-313 ft., with an average of 222 ft. Additionally, the sweet spot intervals are characterized by average TOC values range of 1.6-3 wt.% and type III kerogen, with a little contribution to type II kerogen. The maximum Tmax values were found to range from 462 to 475°C, with average values ranging from 444.3-456°C, measured Ro% values range from 0.7 to 1.09%, with an average value of 1%, and calculated Ro values range from 1.2-1.4 % indicating that the shale already reached the stage of late maturity where it is in the peak of wet gas generation stage. Furthermore, the sweet spot intervals are characterized by excellent petrophysical properties suggesting that the Upper Safa member is conducive to shale gas production. The mineralogical composition varies considerably, with quartz content ranging from 30-63%, carbonate content ranging from 8-10%, and clay content ranging from 22-55%. NMR and Dielectric logs show favorable properties for gas production, with an average NMR porosity of 5% and permeability of 1200-1400 nD. The average water saturation values range between 51-62%, and the average hydrocarbon saturation ranges from 38-49%. The geomechanical properties of the entire Upper Safa shale indicate that the sweet spot intervals have average Brittleness Average (BA) values of 0.33-0.57. The overall findings indicate that the Upper Safa shale has significant potential as a shale gas resource, with sweet spot parameters strongly falling within the typical ranges of the top 10 global productive shale gas reservoirs, including Marcellus, Haynesville, Barnett, Fayetteville, Bossier, Eagle Ford, Muskwa, Woodford, Utica, and Montney shale reservoirs. This could make it an important addition to the global shale gas market.