Petroleum System Distribution And Hydrocarbon Accumulation Correlation Of Typical Cratonic Basins In Eurasia

The craton basin is an important petroliferous region because of its relatively stable and wide distribution of tectonic activities and rich oil and gas resources.At present,the predecessors have obtained a preliminary understanding of the overall study of craton basins,but there is still a lack of systematic summary about the oil and gas systematic summary of different types of basins.Based on a large number of investigations on the global craton basins,this paper selects three typical basins in Eurasia to depict the distribution of source reservoir cap rocks,summarizes the corresponding reservoir forming assemblages and petroleum systems,and analyzes the main controlling factors of hydrocarbon enrichment from the perspective of structure and sedimentation.On this basis,the similarities and differences of the three basins in structural evolution,petroleum system and accumulation combination are discussed,and the evaluation methods for cratonic basins with different ranges and horizons are put forward.The corresponding oil and gas enrichment rules and their prospective areas are clarified,and the application of oil and gas zonal distribution theory in cratonic basins is expanded1.According to the basin scale and formation age,this three basins are divided into Precambrian giant craton basin(East Siberian Basin),Precambrian middle basin(Baltic basin)and Paleozoic small craton basin(Paris basin).The oil and gas resources in each basin are analyzed,and the source reservoir cap rock horizons and ranges of different basins are studied,The main factors controlling hydrocarbon accumulation are proposed.It is pointed out that the degree of geothermal evolution in Precambrian basin is relatively high,the maturity of corresponding source rocks is high,and there are relatively many oil and gas enrichment horizons with a wide range;The Paleozoic craton basin has poor enrichment and high maturity of source rocks.2.The tectonic evolution of the three main cratonic basins in the Eurasian plate can be divided into two stages: early extension,late multi-stage subsidence and short-term compression.It is pointed out that the early extension of the basin resulted in the development of a wide range of stable thick crystalline basement and sedimentary cap rocks,and the later compression resulted in structural inversion and reactivation,which promoted the migration and enrichment of oil and gas.3.In this study,the source reservoir cap rock development horizons and parameter characteristics of the three basins are counted,the lithofacies paleogeographic map of the main horizons and the plane distribution map of source rocks and reservoirs are drawn,and the favorable oil and gas bearing areas are divided.Compared with the geological background,it is pointed out that the oil and gas reservoirs in this area are generally developed with high quality source reservoir cap rocks,lateral changes in sedimentary facies,long lateral migration(mainly Precambrian basin)and short vertical migration(mainly Paleozoic basin),and multistage episodic hydrocarbon expulsion.4.In this study,the evaluation method based on basin scale is proposed,and the sand body superposition method is used for the "sedimentary control reservoir and facies belt distribution" of the giant basin,and the "source rock control reservoir and ring belt distribution" of the two small and medium-sized basins is used for the prediction of oil and gas prospects by the theory of hydrocarbon generating stove ring belt.Comparing with the cratonic basins of Eurasia plate,it is considered that the oil and gas in Precambrian basins are concentrated in the uplift and other high parts,and the oil and gas in Paleozoic basins are concentrated in the depression,graben and other low structural parts.