Thermal conductivity of gas-bearing shale of the Longmaxi Formation in the southern Sichuan

The deep gas-bearing shale in the Longmaxi Formation in the southern Sichuan Basin was used to explore basic characteristics of deep gas-bearing shale and factors controlling those characteristics, such as mineral composition, TOC content, porosity and thermal conductivity. The thermal conductivity of the gas-bearing shale in the Longmaxi Formation in the study area mainly ranged 2.0-3.0 W/(m·K), with a maximum measured value of 5.15 W/(m·K), and a minimum value of 1.22 W/(m·K), averaging 2.50 W/(m·K). On this basis, the relationships between thermal conductivity and mineral composition, porosity, TOC content and temperature were discussed, and the influencing factors of thermal conductivity were analyzed. The thermal conductivity of shale is closely related to mineral composition. Pyrite and quartz are the minerals that have a great influence on thermal conductivity. Furthermore, thermal conductivity decreases with the increasing porosity of shale reservoir. With the increase of TOC content, thermal conductivity decreases. When the value of TOC content is low, the corresponding thermal conductivity decreases rapidly. When the value of TOC content is high, thermal conductivity decreases slowly. Temperature is a most important factor affecting thermal conductivity, which is restricted by the TOC content of shale. When TOC content is low, thermal conductivity decreases with the increase of temperature. When TOC content is high, thermal conductivity increases with the increase of temperature.