Petrological Characteristics And Shale Gas Enrichment Of Organic Matter-rich Shale In Jiangxi Province

Regarding the upper Sinian Piyuancun formation and the lower Cambrian Hetang formation in the northeast of Jiangxi Province, the lower Cambrian Wangyinpu formation and the lower Cambrian Guanyintang formation in the northwest of Jiangxi Province and the upper Permian Leping formation and the upper Triassic Anyuan formation in Pingle depression as the objective strata, TOC,Ro,the type of organic and other characteristics of organic petrology and rock texture and structure, quartz mineral content, clay mineral content, pore characteristics and other routine characteristics are studied by measured field geological section and X-ray diffraction quantitative analysis of whole-rock, organic maceral test, SEM analysis, TOC analysis and other experimental test method. TOC is high(>2%),the main type of organic matter is type I, Ro is in mature-over mature stage, the main mineral composition of shales are clay minerals and quartz mineral, micro-porosity is developed,which indicates that the shale of Jiangxi Province has better material basis of shale gas development. On this basis, the effects of petrological characteristics to pore characteristics, the maximum amount of CH4 adsorbed, accumulation mechanism and recoverable conditions are analysed. It indicates that quartz minerals and clay minerals have different effects on the porosity and permeability characteristics. Diagenesis is the key factor on the formation of pore types. TOC> Clay mineral content> Ro> Quartz mineral content among degree of influence factors affecting the maximum adsorption of CH4. The conversion between minerals, the porosity evolution and the adsorption of liquid hydrocarbons in the process of diagenesis have a certain extent on the occurrence mechanism of shale gas.At the same time, the lithological characteristics of “Hydrocarbon source rocks-Reservoir bed-Cap rock” are the important constraints of the storage conditions of shale gas. In summary, the occurrence condition and preservation condition of organic matter-rich shales are overall good while the storage condition of shale gas in Pingle depression is relatively poor. Finally, the enrichment patterns and enrichment law of shale gas in Jiangxi Province are summarized. the shale gas accumulation model in Jiangxi Province is divided into the accumulation model of coastal phase, high degree of evolution and high organic matter abundance, the accumulation model of deep sea basin facies, high degree of evolution and high organic matter abundance, and the accumulation model of epicontinental sea continental shelf, low degree of evolution and low organic matter abundance. The hydrocarbon potential of shale gas under the first two shale gas accumulation model is better. The closed stable sedimentary environment, high degree of evolution, high organic matter abundance and good porosity development degree are in favor of shale gas enrichment。...