摘要:
提要：四川盆地元坝地区大安寨段湖相泥页岩为研究对象，在样品实验数据分析和岩心观察的基础上，对元坝地区陆相页岩气的形成条件进行了评价，并探讨了陆相页岩气富集高产的主控因素。元坝地区大安寨段泥页岩具有厚度大、有机质丰度高、类型好、热演化程度适中、储集物性以及含气性好、并具有可压性等特点，具备陆相页岩气形成的有利地质条件。元坝地区泥页岩含气量较高，其中吸附气量明显受到温度和压力、TOC、热演化程度（Ro）以及矿物成分的控制，表现为与压力、TOC、硅质和粘土矿物呈正相关，与温度、Ro呈负相关，与碳酸盐矿物相关性不大的特点，影响程度表现为TOC>Ro>硅质>粘土矿物>碳酸盐矿物；游离气量则受孔隙和裂缝发育的影响，其与孔隙度成正相关关系；其中反映孔隙发育程度的基质孔隙度与TOC、粘土矿物含量呈正相关，与石英+长石呈先正相关后负相关（在40%左右最大），与碳酸盐含量呈负相关；裂缝发育程度则受岩性、构造作用、沉积成岩作用以及生烃作用的控制。元坝地区大安寨段陆相页岩气富集高产的主控因素包含了沉积相带、岩相和裂缝发育程度，其中浅湖—半深湖暗色泥页岩是湖相页岩气富集高产的基础；浅湖—半深湖相富有机质泥页岩所夹的薄层（条带）灰岩或砂岩有利于后期的压裂改造；裂缝和“挡板”层控制了页岩油气的高产。
Abstract:
Abstract：Taking Da'anzhai Member lacustrine shale in Yuanba area of Sichuan basin as the study area and based on the sample analysis of the experimental data and the observation of drilling cores, the authors evaluated the conditions for the formation of continental shale gas in Yuanba area and discussed the main factors controlling the enrichment and high production of the continental shale gas. Da'anzhai Member shale in Yuanba area is characterized by large thickness, high abundance of organic matter, good type of organic matter, moderate thermal evolution degree, good gas-bearing reservoir properties and fracturing performance, suggesting favorable geological conditions for the formation of continental shale gas. In Yuanba area, shale gas content of Da'anzhai Member lacustrine shale is higher, the adsorption capacity is affected by temperature and pressure, TOC, and the thermal evolution degree (Ro) and mineral composition; it is characterized by positive correlation with pressure, TOC, silica and clay minerals, negative correlation with temperature, Ro, and insignificant relationship with carbonate minerals. The influence extent is in order of TOC>Ro>siliceous>clay minerals>carbonate minerals. Free gas is influenced by the development of pores and fractures, and has a positive correlation with porosity. Matrix porosity that can reflect the porosity development degree has positive correlation with TOC, clay mineral content, positive correlation followed by negative correlation with quartz and feldspar (maximum 40%), and negative correlation with the content of carbonate. The development degree of fractures was controlled by lithology, tectonics, sedimentary diagenesis and hydrocarbon generation. The main factors controlling the enrichment and high production of Da'anzhai Member shale gas in Yuanba area included sedimentary facies, lithofacies and the degree of fracture development. The dark shale of the shallow and semi-deep lake constituted the foundation of the enrichment and high production of lacustrine shale gas. The intercalated thin layers (or stripes) of limestone or sandstone with organic-rich shale in the shallow-semi deep lake were favorable for hydraulic fracturing in the later period. The fractures and the "baffle" layer controlled high production of continental shale oil and gas.
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