川西孝泉构造上三叠统超致密储层演化特征

川西坳陷孝泉构造上三叠统储层普遍为超致密储层,其中蕴藏的丰富天然气资源可能与天然气的早期聚集有关,认识超致密储层的孔隙演化史有助于确立天然气的大规模聚集时期.作者利用显微镜下观察、扫描电镜分析、阴极发光分析等认识了储层的成岩作用特征,结合自生矿物中流体包体的均一温度、同位素地质温度计和古地温梯度等建立了储层的成岩作用序列.根据储层在压实过程中的原生孔隙损失规律、成岩矿物形成时期及其对孔隙度破坏的定量化统计、次生孔隙的定量化研究等,认识了储层的致密化进程,即储层致密于早-中侏罗世,但在侏罗纪前一般具较好孔隙度.有利于天然气大规模聚集时期为自上三叠统须四段沉积到中侏罗统沙溪庙组沉积末期间.

Evolutionary characteristics of Upper Triassic reservoir in Xiaoquan structure in West Sichuan, China

The Upper Triassic reservoir in Xiaoquan structure in West Sichuan is generally a super tight reservoir, in which abundant natural gas possibly relates to early gathering. It is useful for assuring gas's extensively gathering period to know porosity evolving history of the super tight reservoir. By observing under microscope and analysing under scanning electron microprobe and cathodeluminescence, the author knows the diagenetic characteristics of the resevoir and sets up the diagenetic series combined with homogenization temperatures of inclusions, isotopes, and paleotemperature grades. Through quantitative research on the original pore loss during compaction, porosity change because of diagenesis minerals and secondary pore, the author knows the tightening process of the reservoir. The reservoir had commonly better porosity before Jurassic and was tightened between Early and Middle Jurassic. Above all, the useful period for gas gathering extensively is from the sedimentary period of the Xujiahe 4 section in Upper Triassic to that of Shaximiao Formation in Middle Jurassic.