Assessing shale gas resources of Wufeng-Longmaxi shale (O-3w-S-1l) in Jiaoshiba area, SE Sichuan (China) using Petromod I: Burial and thermal histories

摘要

Burial and thermal histories of Wufeng-Longmaxi shale (O-3w-S-1l) in Jiaoshiba, an important shale gas exploration target in SE Sichuan, were modeled using PetroMod software. Results of Well JY4 show the shale was buried to 2000 m in Silurian, uplifted 1000 m due to a later erosion, subsided again at Permian, and reburied to maximum depth around 6200 m at the end of Cretaceous (K3). Finally, the shale uplifted to the current depth of 2500 m. Thermal history of the shale was reconstructed based on the burial evolution after constrained by measurements. The shale entered oil-window in later Silurian and passed gas generation peak at early Triassic. Thermal maturation accelerated significantly since the Triassic and finalized its maximum maturation (2.0-2.5% Ro) at K3.