川东南綦江丁山地区上奥陶统五峰组—下志留统龙马溪组页岩气地质条件综合评价

Comprehensive Evaluation on Geological Conditions of the Shale Gas in Upper Ordovician Wufeng Formation—Lower Silurian Longmaxi Formation in Dingshan Area,Qijiang,Southeastern Sichuan

本文综合利用钻井、测井、地震及分析化验等资料,在对川东南綦江丁山地区DY1井、DY2井上奥陶统五峰组一下志留统龙马溪组页岩气层含气性分析基础上,探讨了各地质要素对气藏富集和产量的影响。结果表明:丁山地区页岩气地质条件好,具有TOC高、热演化程度适中、储集性能好、含气性较好等特点;构造样式是控制页岩气富集的一个重要因素,正向构造是四川盆地内最有利于页岩气富集的构造类型,而位于盆缘、靠近齐岳山断裂的丁山鼻状断背斜构造,同样有利于页岩气富集,但齐岳山断裂决定了其不同构造部位的含气性;在离齐岳山断裂距离较近、埋深较浅的构造部位,裂缝更加发育,页岩横、纵向渗透性增大,页岩气更容易发生大规模逸散,最终造成页岩气层含气性差。在此基础上,综合页岩埋深、构造特征,将丁山构造划分为浅埋平缓区、西部高角度斜坡区、中部低缓区、东部高角度斜坡区、深埋平缓区5个区带;以优质页岩厚度为基础,"构造与保存条件"为关键,并结合页岩埋深,优选出丁山地区中部低缓斜坡区为最有利区带。

Objectives：Based on the analysis of shale gas-bearing of the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in Well DY1, DY2 in Dingshan Basin, the paper discusses the influences of various geological factors area, Qijiang County, Southeastern Sichuan on the enrichment and productivity of shale gas reservoir. Methods：This paper carries out research with well and logging data comparison, seismic data interpretation and test data et al. Results：The shale gas geological conditions in Dingshan area are advantageous with high TOC, moderate thermal evolution degree, good reservoir properties and gas-bearing. Tectonic style is an important factor for controlling the shale gas enrichment, and positive structure is the most conducive type for the enrichment of shale gas in the Sichuan basin. The Dingshan structure is a nose-like faulted anticline which located in the edge of the Sichuan basin and adjacent to the Qiyueshan fault, it is also favorable for shale gas enrichment. And the Qiyueshan fault controls gas-bearing level in different locations of the Dingshan structure. Fractures are more developed in the locations with short distance to the Qiyueshan fault and shallow buried depth, the horizontal and vertical permeability of shale has obvious increased, shale gas is more prone to large-scale emissions, then finally resulting in poor gas-bearing of shale gas reservoir. Conclusions ：Integrating with shale depth and structural feature, we divide the Dingshan structure into five zones as shallow buried gentle area, western slope area with high angle, middle fiat zone, eastern slope area with high angle and deep buried gentle area. Based on the thickness of high shale, and taking ＂ structure and preservation condition＂ as the key with combination of shale depth, this paper chooses middle fiat zone as the most favorable for shale gas exploration in Dingshan Area