柴达木盆地西部侏罗系油气勘探前景

柴达木盆地西部的侏罗系发育中、下侏罗统大、小煤沟组和上侏罗统采石岭组、红水沟组两套地层。中、下侏罗统以暗色含煤建造为主，暗色泥页岩发育；上侏罗统以氧化环境下沉积的红色碎屑岩建造为主，不具备生烃能力。区域地质调查及地震解释资料揭示中、下侏罗统湖相暗色泥页岩分布广、残留厚度大, 在清水沟和月牙山北分别发育了288m和256m厚的烃源岩。有机地球化学分析表明烃源岩有机碳含量平均达1.62%；有机质类型以Ⅱ2型为主，部分为Ⅲ型；正处于成熟阶段的生、排烃高峰期，具有较强的生烃能力。该区生储盖匹配良好，圈闭发育，具有较好的石油地质条件和良好的油气勘探前景。

HYTROCARBON EXPLORATION PROSPECT OF JURASSIC IN THE WESTERN QAIDAM BASIN

Based on regional geological survey, seismic data and organic geochemistry analysis, the Jurassic sedimentary characteristics and petroleum geological condition in the western Qaidam Basin are studied in this paper. It is indicated that there are two sets of strata developed in the western Qaidam Basin, one is MiddleLower Jurassic dark coal bearing formation, including Xiaomeigou formation and Dameigou formation; another one is the Upper Jurassic red clastic rock formation developed in oxidation environment without hydrocarbon generating capacity. The dark mud shale developed in MiddleLower Jurassic lacustrine facies is widely distributed in the study area with large residual thickness. About 288m and 256m thickness of source rocks are developed in the Yueyashan and the Qingshuigou regions respectively. The organic geochemistry analysis shows that the average organic carbon abundance is 1.62%. The organic matters mainly belong to typeⅡ2 and partly typeⅢ. The source rocks is reaching the peak period of oil generation and discharging and are of better hydrocarbon generation capacity. The source rocks, reservoir beds and the cap rocks match each other well, and traps develops well, it can be concluded that the Jurassic in the western Qaidam Basin possesses relatively better petroleum geological conditions and good oil and gas exploration prospect.