Geochemical parameters of thermal simulation of gas generation on lacustrine Type II shales in semi-open pyrolysis system

A semi-open thermal simulation of hydrocarbon generation experiment was conducted on the lacustrine Type II rocks (the Chang 7 member shale in the Ordos Basin, China). Geochemical characteristics of the hydrocarbon and non-hydrocarbon gas were studied. The yield of hydrocarbon and non-hydrocarbon gas is approximately the same in the whole process of hydrocarbon generation. The cumulative and net increased yield of the hydrocarbon gas were measured and quantified. Gas generation stages are divided and the source of the generation of different gases are studied. Carbon isotopic values of gases generated were tested. The pyrolysis residues at each temperature point were collected and subjected to routine pyrolysis analysis. Based on the experiment, the gas generation can be divided into 3 stages, and different stages have different gas source.