The petroleum generation modeling of prospective affinities of Jurassic–Cretaceous source rocks in Tut oilfield, north Western Desert, Egypt: an integrated bulk pyrolysis and 1D-basin modeling

Abstract

Total organic carbon (TOC) and Rock-Eval pyrolysis for 27 rock samples and geochemical model of Alam El Bueib, Masajid, Khatatba, and Ras Qattara Formations from Tut-1x well in the Tut Oilfield, North Western Desert, Egypt, were used to determine the source rock characteristics and petroleum generative potentials of prospective source rocks, including quantity, type of organic matter, and their thermal maturity level. The results were then incorporated into basin modeling in order to improve our understanding of burial/thermal histories and hydrocarbon generation and extraction from Jurassic–Cretaceous source rocks. The bulk geochemical results showed that Alam El Bueib and Ras Qattara formations contain type-III kerogen, while the Masajid and Khatatba formations displaying generally contain mixed kerogen types II–III, which have the ability to generate mixed oil and gas accumulations under thermal maturation level. Vitrinite reflectance values of the Jurassic–Cretacouse source rocks range from 0.42 to 0.86 % R, indicating sufficient thermal maturity for oil generation. Meanwhile, the burial/thermal history models indicate that the Alam El Bueib and Masajid formations initiated the early-mature stage of oil generation during the Late Cretaceous till the present day and the peak oil generation has not been reached yet. The source rock of the Khatatba and Ras Qattara formations reached to the peak oil generation at vitrinite reflectance values of 0.76 Ro% between 110 and 77 million years before present (mybp), and maximum rates of oil have been generated during late Cretaceous–early Tertiary (100–58 mybp). The transformation ratio of the main phase of oil generation varied from 25 to 65 %. The modeled hydrocarbon generation evolution suggests that the timing of hydrocarbon extraction from the Khatatba and Ras Qattara source rocks began in the early Tertiary (58 mybp) and persisted to the present day. This indicates that Khatatba and Ras Qattara formations can be consider as generative potentials of prospective source rock horizons in Tut oilfield.