湘中-湘东南拗陷泥页岩层系沉积模式及储层特征

中扬子地区湘中、湘东南拗陷泥盆系-二叠系主要发育4套泥页岩层系,其中泥盆系佘田桥组与棋梓桥组泥页岩主要发育于海相台盆内,二叠系龙潭组、石炭系测水组泥页岩则主要发育于海陆交互环境中的滨海-沼泽相内。利用X射线衍射技术、扫描电镜技术、等温吸附技术,并结合区域沉积背景,对湘中、湘东南拗陷页岩层系储层特征进行了全面的分析研究。结果表明,湘中、湘东南拗陷泥页岩层系的岩石矿物成分中石英、碳酸盐矿物、黏土矿物的平均质量分数分别为29.4%、21.2%和44.6%。孔隙类型中既包括连通性较好的格架孔、有机质孔、生物体腔孔等,也包括连通性较差的溶蚀孔。整体孔喉关系较好。湘中地区吸附气量Langmuir体积平均为1.72cm3/g;湘东南地区吸附气量Langmuir体积平均为1.775cm3/g。对比美国Barnett页岩储层特征,认为湘中、湘东南地区泥页岩层系具有良好的储层特征及含气性,具有较高的勘探开发潜力。

Sedimentary mode and reservoir properties of mud shale series of strata in Xiangzhong-Xiangdongnan depression,Hunan,China

In the Middle Yangtze region,there mainly develop four set of mud shale series of strata in Devonian-Permian System of the Xiangzhong-Xiangdongnan depression.Among them,the mud shale of the Devonian Shetianqiao Formation and Qiziqiao Formation mainly develops in the marine basin and that of the Permian Longtan Formation as well as the Carboniferous Ceshui Formation mainly develops in the littoral-swamp facies of the sea and land interaction environments. This paper comprehensively analyzes and studies the reservoir properties of the shale series of strata in the middle of Hunan and the southeast of Hunan using X-ray diffraction technique,scanning electron microscopes technology and adsorption isotherm technique,and considering the sedimentary background.The study result shows that in the shale series of strata in the middle of Hunan and the southeast of Hunan,the contents of quartz,carbonate minerals and clay minerals are 29.4%,21.2% and 44.6%, respectively.The pore types include well-connected hack pore,organic matter pole,biological cavity pole,and poor-connected corrosion poles.The total pore throat relationship is good.The adsorption capacity Langmuir volume in the middle of Hunan is 1 .72 cm3/g on an average and that in the southeast of Hunan is 1.775 cm3/g on an average.Compared with the Barnett shale reservoir properties,this paper indicates that the mud shale series of strata in the middle and the southeast of Hunan have a good gas-bearing property and reservoir properties and great exploration and development potentials.