GEOCHEMISTRY OF THE JURASSIC SOURCE ROCKS IN HAILAR BASIN, INNER MONGOLIA

In the periphery and surrounding areas of the Hailar Basin, 31 samples of Jurassic source rocks from the field are selected to analyze rock pyrolysis, extraction of soluble organic matter from rocks and total organic carbon. In order to study the Jurassic hydrocarbon source rocks in this area, cores from 17 wells are sampled and analyzed. The chloroform extracts of the hydrocarbon source rocks and significant biomarkers are detected qualitatively and quantitatively with gas chromatography-mass spectrometry, aiming to systematically evaluate the geochemical characteristics of the source rocks for further geological survey of oil and gas. The results show that the source rocks in the periphery and surrounding areas of Hailar Basin are of high organic matter abundance, with good hydrocarbon generating condition. The environment of the Jurassic source rocks in Hailar Basin belongs to fresh water-brackish water, with diverse types of organic matter and generally high maturity. The steroids are of mainly regular sterane type. The sediment contains high abundance of tricyclic terpane, mainly as pentacyclic triterpane, reflecting a high content of algae. The content of gammacerane is very low. The advantage of even carbon number of OEP and the absence of high molecular normal paraffin shows that the maturity of hydrocarbon source rock has been degraded by microorganisms in the early stage.