五科1井下古生界流体包裹体特征与天然气成藏期分析

The Characteristics of Fluid Inclusions in Lower Paleozoic System of the Well Wuke 1 and the Analysis of the Reservoir-forming Stage

五科1井位于四川盆地川东高陡构造带五百梯构造,钻达寒武系地层,并在下志留统小河坝组角砾泥岩中发现天然气藏。通过对该井下古生界地层裂缝充填物的系统取样分析,发现志留系样品包裹体均一温度为210℃左右,含有大量天然气,而寒武系包裹体样品均一温度较低,为150℃左右,不含天然气。综合包裹体信息和地质研究认为,五科1井下志留统小河坝组气藏中的天然气来自龙马溪组黑色页岩,成藏期为燕山晚期。下寒武统源岩对中上寒武统以上地层天然气成藏没有贡献。

Well Wuke 1 is located in Wubaiti structure, eastern Sichuan basin. This drilling well has intersected the Cambrian strata and a natural gas reservoir in the brecciated mudstone of the Lower Silurian Xiaoheba Formation. A series of fluid inclusion samples were collected from the core of the I.ower Paleozoic strata. The homogenization temperatures of natural gas-bearing inclusions in Lower Silurian samples are around 210℃ while those of inclusions without natural gas in Upper-Middle Cambrian strata are about 150℃. Based on the comprehensive fluid inclusion and geological studies, it is believed that the natural gas in the Xiaoheba Formation was sourced from the dark shale of the Lower Silurian Longmaxi Formation, and the pool was formed in late Yanshanian. The Lower Cambrian strata has made no contribution to form the gas reservoir in the strata above the Upper-Middle Cambrian strata.