School of Energy Resources, China University of Geosciences (Beiing)

为寻找页岩气有利富集区,就我国页岩气勘探开发正所处起步阶段所获得页岩气富集成藏机理以及形成条件的主要地质控制因素进行了研究。结果表明:页岩气成藏过程兼具典型煤层气、典型,根缘气和典型常规圈闭气成藏特点,并受总有机碳(TOC)含量、有机质成熟度、矿物组成、孔裂隙和裂缝、页岩层厚度、埋深以及地层压力等多种地质因素影响,其中前4种为主要控制因素;TOC含量越大,生烃潜力越大,且气体储集能力越大,越有利于页岩气富集;热成因气藏页岩有机质成熟度越高,越有利于气体富集,最大镜质组反射率R o为1.1%~3.0%;生物成因气藏页岩Ro越大,越不利于成藏;矿物成分反映了页岩的沉积环境,其对气体含量的影响,主要是影响有机碳含量;微小孔隙影响吸附气含量,粒间孔隙及裂隙影响游离气含量;裂缝对页岩气藏具有破坏作用。

For finding out the favorable enrichment zone, it is significant to study the mechanism and conditions of shale gas enrichment at the early stage of explo ration and development.The mechanisms and conditions controlling shale gas enrichment were summarized in this paper.The results show that the accumulation proces s of the shale gas possesses the comprehensive characteristics of typical coalbed methane, source-contracting gas and entrapped gas enrichments.The shale gas enri chment is influenced by multiple geologic factors including total organic carbon (TOC) content, maturity of organic matter, mineral composition, pore-fracture and crack, thickness, burial depth and reservoir pressure and others, among which the former four factors are the main shale gas reservoir-forming conditions.Higher TOC content in shale is much favorable for gas enrichment due to the larger hydrocarbon-generating potential and storage capacity for shale.Thermogenic gas content will increase with the increasing thermal maturity (R 0) of shale, particular in the range of 1. 1%3.0%, while it is unfavorable for the accumulation of shale gas as R 0 increase for biog enic gas reservoir.Mineral matters reflect the depositional environment of shale, which affects the gas enrichment resulting from affecting the organic carbon content.Mi cropores affect adsorbed gas content, and intergranular pores and fractures influence free gas content.Cracks have destructive effects on shale gas reservoir.

国家自然科学基金与中国石油化工联合基金资助项目(U1262104)；