川西坳陷侏罗系沉积岩相与生烃关系研究

Jurassic sedimentary facies and hydrocarbon generation in the West Sichuan depression

笔者从生烃角度分析和研究了川西坳陷侏罗系沉积岩相 ,川西坳陷早侏罗世—中侏罗世早期最好的生烃沉积环境是长年湖 ,其次为时令湖。在对烃源岩的系统采样分析与研究的基础上 ,对有机碳、有机质类型、有机质演化程度、生气率、生聚系数和体积参数进行了深入的研究 ,并取得了可靠的参数。采用天然气有机碳发生率法与有机显微组分发生率法 ,计算了川西坳陷侏罗系生烃量为 (2 92 4 83 3～ 33342 5 0 )×10 8m3,生烃聚集的资源量为 (350 9 8～4 0 0 1 1)×10 8m3,这对侏罗系远源成藏聚集效率有不可忽视的重要作用。目前川西坳陷所获储量仅占远景资源量的 10 % ,川西坳陷侏罗系勘探高峰远未来到 ,仍有大量的油气资源量待发现 ,储量仍将有一个高速增长期。笔者通过综合研究认为侏罗系为勘探前景与经济效益较好的区域。

The Jurassic sedimentary facies in the West Sichuan depression are discussed in this paper. The most favourable hydrocarbon generating conditions in the study area during the Early Jurassic and early Middle Jurassic consist primarily of perennial lakes and subordinately of seasonal lakes. The organic carbon and organic matter types, organic matter evolution, gas generation rates, coefficients for generation and accumulation, and parameters for volumetric variations are dealt with in detail and reliable results have been obtained. The hydrocarbon production varies between 292483.3 and 333425.0×10 8m 3 for the Jurassic sedimentary rocks, and inferred oil and gas reserves range between 3509.8 and 4001.1×10 8m 3 in terms of organic carbon production and organic microcomponient production in natural gas. This is significant for the study of the Jurassic distant gas accumulation efficiency. Up to now, only about 10% of the total gas reserves are found in the study area. The bulk of future gas will be found and the promise of large discoveries lies also in this area with significant investment in research and development. In these cases, the target areas and prolific areas are both delineated in this study.