湖南扬子地区志留系龙马溪组页岩气成藏条件及前景评价

湖南地处扬子陆块和华夏古陆过渡区,湘西北地区至雪峰山东南缘基本位于扬子地台,此区域属南方海相页岩气远景区。本文主要选取地质构造条件优越、页岩气特征较为明显的龙马溪组黑色页岩层作为主要研究对象。研究表明,龙马溪组黑色页岩分布面积广、有机碳含量高(TOC平均值为2.0%)、热演化程度高(Ro平均值为2.59%)、低孔低渗(孔隙度平均值为2.3%、渗透率小于0.04×10-3μm2);黑色页岩产出厚度在石门-桑植复向斜至龙山、来凤一带较厚,基本大于30 m。而其整体埋深范围在1000~2000m之间为主,产出较为平缓。总体认为,此套含气页岩有待进一步详细勘探和研究,也是十分有开发潜力的页岩气目标层。优选区集中在石门-桑植复向斜至雪峰山东南缘。

Reservoir-forming conditions and perspectives of shale gas in the Silurian Longmaxi Formation of Yangtze area,Hunan Province

Hunan Province is located in excessive belt between Yangtze and Cathaysia, and the northwestern Hunan to the southeast Xuefeng orogeny locate in Yangtze platform which belongs to the prospects Of shale gas in southern marine. To select the Longrnaxi Formation black shale as the main study object which have a favorable geological conditions and the more obvious features of shale gas. The results shows that the shale is characterized with wide distribution, high organic content （the average of TOC is 2.0%）, high organic thermal evolution degree （the average of Ro is 2.59%）; the low-porosity and low-permeability （the average of porosity is 2.3%, and the av- erage of permeability is less than 0.04 ×10-3 μm2）; the output thickness of black shale in Shimen-Sangzhi synclinorium to Longshan-Laifeng area is above 30 m; depth range is mainly between 1000 - 2000 m, and rock occurrence is relatively fiat. In short, this set of black shale should do further explorate and study. At the same time, it is a very promising shale gas target layer. Preferred areas are concentrated in Shimen-Sangzhi synclinorium to the southern edge of the Xuefeng Mountain.