Organic richness and thermal maturation of the F and G members of the Abu Roash Formation in Central Beni Suef Basin, Western Desert, Egypt: Integrated organic geochemical and geophysical approaches

Beni Suef Basin has a promising prospect for hydrocarbon production in the Egyptian Western Desert, so it has been given priority in exploration plans. Geochemically determined TOC data are expensive and are usually obtained from limited samples as in the Beni Suef Basin. Thus, geophysical methods will be used to provide a cost effective continuum of organic richness and maturation data of the latest Cenomanian "G" and the Turonian "F" members of the Abu Roash Formation in the Azhar E-2X well. An attempt was made to differentiate between total organic carbon (TOC) content of kerogen in potential source intervals and TOC content in hydrocarbon bearing reservoir intervals using the Δlog R technique and the gas chromatography data (Gas wetness ratio: GWR%, Light to heavy hydrocarbon ratio: LHR%, Oil character qualifier: OCQ). In the source rock intervals, a good match between the geochemically determined TOC and log-derived TOC data was found, where the later TOC data reliably determined the organic richness. Additionally, the geophysically estimated maturation index (MI) values were calibrated with the geochemical Tmax data. A continuum of MI data successfully provided a reliable assessment of thermal maturation of source rock intervals. Conversely, in gas bearing reservoir intervals, both the log-derived TOC and MI data were hampered by the gas effect. Carefully distinction between reservoir and source intervals in unconventional source rocks having intraformational reservoir interbeds is necessary to determine correctly the organic richness and maturation of these source rocks.