ALBERT

Description: Late Jurassic – Early Cretaceous shales of the Naifa, Safer, and Madbi formations were studied to evaluate source rock characterization. The results of the source rock were then incorporated into basin modeling to understand the timing of hydrocarbon (HC) generation and expulsion. The Late Jurassic – Early Cretaceous shales have low to high organic matter, with total organic carbon (TOC) values in the range of 0.50%–28.01%, indicating fair to excellent source rock potential. Main oil and gas are anticipated to be generated from the Naifa, Safer, and Lam shale samples with types I and (or) II and types II–III kerogens. In contrast, the Meem samples are dominated by type III kerogen (hydrogen index, HI 〈 200 mg HC / g TOC), and are thus considered to be gas prone. The Late Jurassic – Early Cretaceous shale samples have temperatures of maximum pyrolysis yield ( T max ) in the range of 337–515 °C, consistent with immature to post-mature stages. The T max data also indicate that the Safer and Madbi shale samples have sufficient thermal maturity, i.e., peak–mature oil and gas window. The basin models indicate that the Naifa Formation is early–mature, and the onset oil generation began during the Early Miocene. The models also indicate that the main phase of oil generation in the Safer source rock began during the Late Eocene. In contrast, the Madbi source rock units had passed the peak oil generation window, and the oil was converted to gas during the Late Cretaceous to Late Eocene. The modeled HC expulsion history reveals that most oils are contributed by both Madbi units, with significant amounts of gas originating from the Meem unit.

Description: The Middle Jurassic Khatatba Formation in the northern Western Desert of Egypt was evaluated in terms of organic matter abundance, type and thermal maturity, as well as for some organic petrographic characteristics. Depositional environments were interpreted based on organic geochemical (Rock-Eval pyrolysis, extract analysis, and biomarker distributions) and organic petrological methods. Organic carbon contents range between 1.0 and 32.5 wt. %. The Khatatba shale and coaly shale samples have hydrogen index values in the range of 63 to 261 mg hydrocarbon (HC)/g total organic carbon, with mixed types 2–3 and 3 kerogens. Mean vitrinite reflectance (R o ) between 0.77 and 1.07% is in reasonably good agreement with pyrolysis T max (temperature at maximum of S 2 peak) data (438–459°C). Organic-rich sediments of the Middle Jurassic Khatatba Formation have very good source rock generative potential and have obtained thermal maturity levels equivalent to the oil window. The main generation products are gas with very limited liquid HCs (oil or condensate). Seven shale and coaly shale samples from Khatatba Formation were characterized using gas chromatography (GC) and GC–mass spectrometry techniques. The Khatatba samples are characterized by the predominance of C 14 -C 24 alkanes, a pristane/phytane ratio of less than 2, abundant C 27 regular steranes, and the presence of tricyclic terpanes. These are consistent with the suboxic marine-environment conditions for the Khatatba source rock. Biomarker parameters for these samples generally indicate a mixture of land- as well as marine-derived organic-matter input. The maturity indicators based on C 32 22S/(22S + 22R) homohopane and C 29 20S/(20S + 20R) and ββ/(ββ + αα) sterane ratios reveal that the Khatatba samples are thermally mature and have reached the peak oil-window maturity supporting the R o data.

Description: Paleogene Umm Er Radhuma and Ghaydah and Neogene Sarar source rocks from Sayhut subbasin in the Gulf of Aden Basin were studied to provide information such as organic-matter types, paleoenvironmental conditions, and petroleum-generation potential. This study is based on whole-rock organic-geochemical analyses and organic petrology. The total organic carbon (TOC) contents of the Paleogene to Neogene source rocks range from 0.43% to 6.11%, with an average TOC value of 1.00%, indicating fair to very good source-rock potential. The Paleogene Ghaydah and Umm Er Radhuma source rocks are relatively higher in genetic petroleum potential than Neogene Sarar source rocks. Mainly oil and gas are anticipated from the Ghaydah and Umm Er Radhuma source rocks with hydrogen index (HI) values ranging from 95 to 715 mg hydrocarbon (HC)/g TOC. This is supported by the presence of significant amounts of liptinite macerals in the Ghaydah and Umm Er Radhuma source rocks. The Sarar source rocks are dominated by vitrinitic type III kerogen (HI 〈 200 mg HC/g TOC) and are thus considered to be gas source rocks. The Paleogene to Neogene source rocks have vitrinite reflectance ( R o ) values in the range between 0.30% and 0.77% R o , and pyrolysis maximum temperature values range from 412°C to 444°C (774°F to 831°F), consistent with the immature to early mature oil window. Therefore, the present-day kerogen type in the Paleogene to Neogene source rocks is original and should not have been altered by thermal maturity. The biomarker of organic matter suggests that the Paleogene to Neogene source rocks were deposited in a marine environment under suboxic to anoxic conditions. The biomarkers also indicate that the Paleogene to Neogene source rocks contain a mixture of aquatic organic matter (planktonic and bacterial) and terrigenous organic matter, with increasing terrigenous influence to Sarar source-rock samples. Highly hypersaline reducing conditions are also evidenced in Ghaydah and Umm Er Radhuma source rocks, as indicated by the presence of the gammacerane biomarker, low pristane to phytane ratios, and homohopane distribution patterns.