PETROLEUM SYSTEMS AND EXPLORATION PROSPECT OF MESOZOICIN ORDOS BASIN, CHINA

摘要

The Ordos basin is the third largest sedimentary basin in China. It is famous forthe largest natural gas field of Paleozoic and abundant oil resources of Mesozoic in China. In this study,mudstones, coal rocks and oil samples from the Triassic Yanchang Formation and the Jurassic Yan’anFormation in the basin were analyzed geochemically in detail. The abundance, property and thermalmaturity of organic matter indicate that the Yanchang Formation has a larger and strongerhydrocarbon-generating potential than Yan’an. Burial history and thermal history study indicate that thecritical moment is 105Ma..The time extent of oil generation, migration and accumulation is from 110Ma through 100 Ma.. Oil –rock correlations indicate that the oil reserved in the Yanchang Formationhas the same geochemical properties with the oil reserved in the Yan’an Formation, and all of the oilshave the same and only source rock of the Triassic Yanchang Formation. Based on the basic conceptsof petroleum system, fully considering the characteristics of the geological and sedimentarybackground of the Ordos basin, two petroleum systems of Mesozoic in the basin were classified. Theyare Northeast Yanchan - (Yan’an+Yanchang) System (!) and Southwest Yanchang - (Yan’an+Yanchang)System (!). After a comprehensive study of petroleum geochemistry and geology, three target areas forthe next exploration of Mesozoic in the basin were suggested.