Hydrocarbon Generation Characteristics of Coal‐measure Source Rocks and their Contribution to Natural Gas: A Case Study of the Middle and Lower Jurassic Targets from the Southern Margin of Junggar Basin

Abstract

AbstractIn order to study the hydrocarbon generation (HC‐GE) characteristics of coal‐bearing basins, the coal measure source rocks of the Middle‐Lower Jurassic (ML‐J) in the southern margin of the Junggar Basin (study area) are taken as the research objects. More than 60 samples of the ML‐J were collected from outcrops and wells. Total organic carbon (TOC), rock pyrolysis (Rock‐eval), organic petrological, vitrinite reflectance (%Ro), and hydrous pyrolysis were performed on the relevant samples. The pyrolysis gases and liquid products were measured respectively, and then the chemical composition, as well as carbon isotopes of the gases, were analyzed. The results indicate that the ML‐J source rocks have the capacity for large‐scale gas generation. In addition, for coal measure source rocks, the heavier the carbon isotope of kerogen (δ13Ckerogen) is, the lower the liquid hydrocarbon and hydrocarbon gas yield, and the easier it is to produce non‐hydrocarbon gas. It is worth noting that when the δ13Ckerogen in organic matter (OM) is relatively heavier, the fractionation of its products may be weaker in the evolution process. The vital contribution of the ML‐J source rock to natural gas resources in the study area was further confirmed by comparing it with the Jurassic source gas.