Pore structure evolution of lacustrine shales containing Type I organic matter from the Upper Cretaceous Qingshankou Formation, Songliao Basin, China: A study of artificial samples from hydrous pyrolysis experiments

Abstract To characterize the pore evolution of lacustrine shales containing Type I organic matter, we performed hydrous pyrolysis experiments on a lacustrine shale sample to make it reach various maturities. The samples with various maturities were then extracted using dichloromethane. Total organic carbon content, Rock-Eval pyrolysis, and low-pressure gas (CO 2 and N 2 ) adsorption analyses were performed on the samples before and after extraction. The results showed that the volumes and surface areas of micropores ( R o before increasing at EASY% R o values exceeding 1.08%. The changes in micropore volume of the extracted samples may be related to the formation and cracking of insoluble organic matter. During this process, mesopore volumes kept increasing, which is mainly aroused by kerogen decomposition or carbon loss. Our results could improve the understanding of pore evolution of lacustrine shales and provide some implications for shale oil storage.