基于沉积区域分类的鄂尔多斯盆地延长组长7段页岩孔隙发育影响因素研究OA

The Chang-7 Member of the Yanchang Formation in the south-central Ordos Basin was selected as the research object.Based on the measured data from 41 wells,the Kriging interpolation and Partial Least Squares Regression(PLSR)were adopted to systematically analyze the main controlling factors of pore development under different geological conditions.The results show that when the Total Organic Carbon(TOC)content is less than 6%,the samples are mainly distributed at the lake basin margin,and the total content of the main brittle minerals(quartz and feldspar)exhibits a significant negative correlation with TOC.When the TOC content exceeds 6%,the samples are mainly distributed in the central lake basin,and there is no obvious correlation between the total quartz and feldspar content and TOC.There are remarkable differences in the main controlling factors of pore development in different regions of the lake basin around the TOC critical point(6%).Pore development in the central lake basin is mainly controlled by TOC and pyrite content,where the negative impact of TOC on pore development is manifested as pore filling by solid bitumen.In contrast,pore development at the lake basin margin is mainly dominated by the content of carbonate minerals and chlorite:the cementation of carbonate minerals damages reservoir pores,while chlorite protects reservoir pores by weakening cementation and enhancing the compaction resistance of rocks.