Hydrocarbon generating-potential and maturity-related changes of the Khatatba Formation, Western Desert, Egypt

Abstract

Abstract The petroliferous province of the Western Desert comprises several sedimentary basins with different hydrocarbon potentiality and production capability. The middle Jurassic Khatatba Formation was proved a potential source rock in some basins and active/effective in others. The current study aims to give a comprehensive assessment and evaluation of the potential organic-rich intervals of the Khatatba Formation across JG and JD fields, northeast Abu Gharadig Basin (NEAG). The hydrocarbon generating capability and sourcing of the Khatatba Formation studied through organic geochemistry calibrated with well logging. However, the efficiency of some widely used plots of geochemistry is re-evaluated according to their accuracy and consistency. Forty cuttings, thirteen cores and two oil samples obtained from three wells (JG-2, JG-3 and JD-4) were evaluated. The samples revealed total organic carbon (TOC) values ranging from 1 to 9\u202fwt%, exhibiting a good-excellent potential source rock. A single sample in the JD-4 well attained a TOC value of 21.3\u202fwt% with a generating potential (represented by S2 parameter) exceeding 146 mgHc/g rock required a special evaluation. Most of the samples (mainly in the JD-4 well) attained a sufficient level of thermal maturity for hydrocarbon generation with a Tmax up to 449\u202f°C. The vitrinite reflectance (%Ro) values (a common maturity-related indicator) acquired from the JD-4 well ranging between 0.76% and 0.92%. These values are tediously increasing with depth indicating a uniform geothermal regime. The Khatatba organofacies, with wide variety of kerogen types (I, II, II-S and II/III), contain marine organic matter with a slight terrigenous input, exhibiting anoxic-suboxic environmental conditions. Oil-source correlations define the organic-rich intervals responsible for charging the accumulated hydrocarbon in the NEAG concession.