四川盆地及其周缘上奥陶统—下志留统页岩气聚集条件

通过对25处野外露头的观测、采样以及吸附气含量、地化参数和物性参数等测试分析,研究了四川盆地及其周缘上奥陶统—下志留统黑色页岩的沉积相、厚度及分布、有机质类型及含量、成熟度、孔隙度和含气量等页岩气成藏条件。与美国主要产气页岩相比,研究区发育的页岩具有沉积相有利、厚度大、有机碳含量高、成熟度高、孔隙度高和含气量高等特点,具备页岩气藏发育的良好地质条件。此外,建立了预测页岩气藏发育有利区的参数模型,采用综合信息叠合法预测四川盆地及其周缘上奥陶统—下志留统页岩气藏的有利发育区位于川南-黔北、鄂西-渝东和川(渝)东北-鄂西北等地。在各个有利区的具体指标中,川南-黔北有利区具有较高页岩含气量,是目前勘探较为现实的地区。根据实测含气量,采用体积法计算研究区上奥陶统—下志留统页岩气资源量为(2.2～8.5)×1012m3,中值为5.3×1012m3。

Shale gas accumulation conditions of the Upper Ordovician-Lower Silurian in Sichuan Basin and its periphery

The sedimentary facies,thickness,distribution,organic matter types and content,maturity,porosity,and gas content,of the Upper Ordovician-Lower Silurian dark shale in the Sichuan Basin and its periphery are investigated by field observation and sampling on 25 outcrops and laboratory test of adsorbed gas content,geochemical and physical parameters.In comparison with the major producing gas shales in U.S.,the shale in the study area features in favorable sedimentary facies,large thickness,high TOC,high maturity,high porosity,and high gas content,all being favorable geological conditions for shale gas reservoir development.Parameter models were built for predicting shale gas play fairways.The results show that the shale gas play fairways in the study area occur in the Southern Sichuan-Northern Guizhou,Western Hubei-Eastern Chongqing and Northeastern Sichuan(Chongqing)-Northwestern Hubei,among which the Southern Sichuan-Northern Guizhou play fairway is relatively high in gas content,thus is most prospective in shale gas exploration at present.With the measured gas content,the volumetric method gave a resource volume in the range of 2.2-8.5 TCM and a median value of 5.3 TCM.