中上扬子地区下古生界海相页岩气储层特征及勘探潜力

Characteristics and exploration potential of Lower Paleozoic marine shale gas reservoir in middle-upper Yangtze area,China

中上扬子地区下古生界海相地层中发育多套富有机质泥(页)岩,成为中国南方页岩气勘探开发的重点地区。作者在对油气藏成因类型进行划分的基础上,认为该类泥(页)岩油气藏属于源岩油气藏的一种。按照控制源岩型气藏分布的主要地质参数,分析了中上扬子地区下寒武统筇竹寺组/牛蹄塘组和下志留统龙马溪组2套富有机质页岩储层的有机碳含量、有机碳质量分数>2%的页岩层厚度及Ro分布特征。通过分析认为这2套地层有机质丰度高、热演化程度高、分布广泛,具备页岩气赋存的基本地质条件。根据这2套页岩气储层分布特征,确定筇竹寺组/牛蹄塘组泥(页)岩气藏有利勘探区块在川南、鄂西和黔北地区;龙马溪组泥(页)岩气藏勘探有利区块分布在川南-滇北区块、川东-鄂西区块和川北区块。

In the Lower Paleozoic marine facies of the middle-upper Yangtze area of China, there develop sets of mud shale source rocks. They become the important areas of the shale gas exploration and development in the south of China. On the basis of classifying the genetic types of oil and gas reservoirs, the authors consider that this mud shale oil and gas reservoir belongs to one of the source rock oil and gas reservoirs. Based on controlling the main geological parameters of the source rock type gas reservoir distribution, the authors analyse the distribution characteristics of the content of TOC, the mass fraction of TOC （V0;oc））2% shale rock thickness and Ro of the two rich in organic shale reservoirs in Qiongzhusi Group and Niutitang Group of the middle-upper Yangtze area. The authors think that the abundance of organic mass of these two reservoirs is high, the degree of thermal evolution is high and the distribution of the mud shale in the two strata is wide based on the analysis results and that these two reservoirs have the basic geological conditions for the occurrence of shale gas. Based on the characteristics of the shale reservoir distribution, it can be sure that the favorable exploration blocks of the Qiongzhusi Group and Niutitang Group mud shale gas reservoir are located in South Sichuan, North Guizhou, and West Hubei, and that of the Longmaxi mud shale gas reservoir in South Sichuan-North Yunnan, East Sichuan-West Hubei and North Sichuan.