| Based on observation and test analysis of the gas-bearing shale samples from eight drilled wells and two outcrops, it is shown that the Lower Silurian lower Longmaxi shale reservoir is organic-rich and over-mature in Dianqianbei Depression and its adjacent area. The analysis of X-ray diffraction indicates that the Longmaxi shale is composed of clay minerals, quartz, calcite, feldspar, dolomite, pyrite etc., and illite is predominant in clay minerals. The average brittleness index of the shale is distributed from 56.11% to 73.21%, which makes it easy to form the network fractures.The test of conventional physical properties shows that porosity and permeability are low in the shale, but the observation by ESEM shows that nanometer-scaled pores and fissures develop. |
