四川盆地中部上三叠统香溪群岩性油气藏圈闭类型及其特征

四川盆地川中地区构造平缓,大型断裂欠发育,已发现的油气藏与背斜关系并不十分密切。研究认为,川中地区香溪群主要发育岩性圈闭,根据圈闭形成主控因素,结合香溪群沉积前的古地貌特征和裂缝发育特点,将川中香溪群岩性圈闭划分为4种类型:①与地层尖灭相关的地层—岩性圈闭;②与沉积—成岩相变密切相关的成岩—岩性圈闭;③与古地貌有关的差异压实作用形成的岩性圈闭;④与断层转化调节相关的裂缝—岩性复合圈闭。其中成岩—岩性圈闭和地层—岩性圈闭,是川中香溪群最重要的、分布最广泛的圈闭类型。

Trap Types and Their Characteristics of Lithologic Oil-gas Reservoirs in Xiangxi Group in Upper Triassic, Central Sichuan Basin

There are several gentle structure traps and small faults developed in central Sichuan Basin, some discovered oil-gas reservoirs are not related to anticlines. It is thought through related research that the lithologic traps mainly developed in Xiangxi Group. According to the factors that controlled the formation of traps , paleo-geomorphology feature before Xiangxi Group deposition and fracture feature, lithologic trap types can be divided to four types, including: (1) stratigraphic-lithologic trap is related with stratigraphic pinch out;(2) diagenesis-lithologic trap is related with the facies variation of deposition and diagenersis;(3) differential compaction-lithologic trap is related with paleo-geomorphology;(4) fracture-lithologic trap is related with the transformation and adjustment of faults. Among theses, diagenesis-lithologic trap and stratigraphic-lithologic trap are regarded as the most important and extensive type distributed in central Sichuan Basin.