埃及西沙漠盆地中生界烃源岩特征及剩余资源分布

西沙漠盆地是埃及三大主要含油气区之一，已发现大量的油气田，现处勘探发现中期，预探风险增大。为此，在详细评价盆地烃源岩地球化学特征基础上，运用盆地数值模拟技术定量分析剩余资源潜力。研究认为，中侏罗统Khatatba组Safa段和Zahra段煤系暗色泥页岩以及上白垩统Abu Roash组AR-F段暗色泥页岩是盆地的3套主力烃源岩，各凹陷烃源岩广泛分布，厚度变化较大。Khatatba组烃源岩TOC含量在0.5%~10%，裂解烃S₂含量高，为中等-很好烃源岩；Abu Roash组AR-F段烃源岩TOC主要在0.5%~3%，裂解烃S₂含量中-高，属中等-好烃源岩。这3套烃源岩有机质干酪根类型以混合Ⅱ型为主，其次是Ⅲ型，少量为Ⅰ型。指出Khatatba组2套烃源岩全盆处于热演化成熟大量生排烃阶段，凹陷中心达高熟生烃、局部过熟生气阶段，油气并生；Abu Roash组AR-F段烃源岩仅Abu Gharadig和Natrun凹陷进入成熟生烃阶段。提出盆地北部地区主要由侏罗系Khatatba组烃源岩供给油气，东南部地区则有侏罗系Khatatba组和白垩系AR-F段双源供烃。计算表明，盆地剩余可采资源量达6.51×10⁸ t，剩余资源潜力很好；其中，南部Abu Gharadig凹陷古生界、侏罗系和下白垩统AEB，北部Matruh凹陷古生界、Faghur凹陷上白垩统，油气探明程度低，剩余资源可观，为下步勘探的有利方向。

Geochemical characteristics of the Mesozoic source rocks and the remaining resources in the Western Desert Basin,Egypt

The West Desert Basin is one of the three major hydrocarbon-bearing areas in Egypt, with a large number of oil and gas fields discovered therein.At the middle stage of exploration and discovery now, the risk of preliminary prospecting increases.The study focuses on the quantitative analysis of remaining resource potential by basin numerical simulation technology following the detailed evaluation of geochemical characteristics of the source rocks.The results show that the dark shale of coal measures in the Safa and Zahra members of the Middle Jurassic Khatatba Fm and that of the AR-F member in the Upper Cretaceous Abu Roash Fm are the three sets of major source rocks in the basin; and the source rocks are widely distributed in each depression with the thickness varying greatly.The source rocks in the Khatatba Fm have a TOC content ranging from 0.5% to 10% and a high content of cracked hydrocarbon S₂, thus are fair-to-very good source rocks.While the AR-F source rocks in the Abu Roash Fm have a TOC content varying between 0.5% and 3% and a moderate-to-high content of cracked hydrocarbon S₂, thus belong to fair-to-good source rocks.The kerogen of these source rocks is dominated by mixed Type II, followed by Type III and minor Type I.It is pointed out that the two sets of source rocks in the Khatatba Fm within the whole basin are at the thermal evolution stage of hydrocarbon generation and expulsion in a large amount; that in the center of the depression reaches high mature stage and even over mature stage locally, with oil and gas co-generated.As for the AR-F section of the Abu Roash Fm, only the source rocks in Abu Gharadig and Natrun Sags enter the mature stage of hydrocarbon generation.It is suggested that the hydrocarbons in the northern part of the basin are mainly contributed by the source rocks of the Jurassic Khatatba Fm, while those in the southeastern part are supplied by source rocks in both the Jurassic Khatatba Fm and the Cretaceous AR-F section.The calculation shows that the remaining volume of recoverable resources in the basin reaches up to 6.51 x 108t, indicating huge resource potential.The Paleozoic, Jurassic and Lower Cretaceous AEB in the Abu Gharadig Sag in the south, and the Paleozoic in the Matruh Sag and the Upper Cretaceous in the Faghur Sag in the north, are low in exploration maturity and high in remaining resource potential, thus being favorable targets for future exploration.