四川盆地五指山地区烃源岩特征与评价

五指山构造区位于四川盆地西南边缘，由于构造运动频繁、地质条件复杂，在一定程度上制约了其油气勘探进程。根据区域地质调查结果以及实测的有机地球化学数据，分别从残余有机碳含量、有机质类型、有机质成熟度以及生烃强度等4个方面对其烃源岩进行定量评价。结果表明：该区烃源岩主要发育在下寒武统筇竹寺组、下志留统龙马溪组、下二叠统；烃源岩有机质类型好，主要以腐泥-偏腐泥混合型为主；成熟度较高，现今处于高成熟-过成熟阶段，以产气为主；生烃强度计算结果表明，下寒武统、下志留统烃源岩条件最好，是其主力烃源层系，平均生烃强度分别为：63×10⁸m³/km²、44.5×10⁸m³/km²。从烃源岩条件看，五指山构造具备形成大中型气田的物质基础。

Features and evaluation of source rocks in Wuzhishan area of Sichuan Basin

The Wuzhishan structure, located in the southwest margin of the Sichuan Basin, has experienced frequent tectonic movements and its geologic conditions are very complex, which impedes petroleum exploration and development to some ex-tent. The data of regional geological survey and organic geochemical measurement are used to quantitatively evaluate the source rocks in aspects of residual organic carbon content, types of organic matter, maturity of organic matter, and intensity of hydro-carbon generation. The following results are obtained. (1)The source rocks are mainly distributed in the Lower Cambrian Qiongzhusi Formation, the Lower Silurian Longmaxi Formation, and the Lower Permian Yangxin Series. (2)The organic ma-terials are dominated by kerogen of type Ⅰ-Ⅱ_1 in highly mature to post mature stages and are gas prone. (3)The results of hy-drocarbon generation intensity calculation show that the source rocks in the Lower Cambrian and Lower Silurian are the best in source rock conditions, with an average hydrocarbon generation intensity of 63 × 10~8m~3/km~2 and 44.5 × 10~8m~3/km~2 respective-ly. The source rock conditions reveal that the Wuzhishan structure has the potential to form large-to medium-sized gas fields.