Study on the Difference of Hydrocarbon Generation and Transformation of Lacustrine Shale in China Based on the Kinetic Mechanism Method

Investigation of the dynamic transformation characteristics of hydrocarbon generation and evaluation of hydrocarbon potential and expulsion are of guiding significance for the evaluation of lacustrine shale oil and gas resources. A total of 1977 pyrolysis dataset points were collected from lacustrine shale samples selected from 202 wells across eight regions within five basins in China. The kinetic parameters were derived, and the original hydrogen index was obtained to identify the kerogen types. Subsequently, the original total organic carbon was estimated to analyse organic matter enrichment. Finally, the hydrocarbon generation, retention and expulsion characteristics of the lacustrine shales were compared. The results demonstrate that lacustrine shales in China exhibit different hydrocarbon generation, retention and expulsion characteristics, which are controlled by both basin lake type and primary productivity. Type I kerogens exhibit the largest hydrocarbon generation and retention amounts and the highest hydrocarbon expulsion efficiency. These kerogens also exhibit the narrowest hydrocarbon generation window and the earliest hydrocarbon expulsion. However, when the source rocks have a high sulphur content, hydrocarbon generation and expulsion occur earlier. Furthermore, when the source rock contains large amounts of terrestrial organic matter input, the hydrocarbon generation and expulsion windows broaden.