Controlling factors of oil-gas accumulation in the foreland basin of North Sichuan Basin

Northern part in Sichuan basin was controlled by multistage actions of surrounding orogenic-zones which result in many superpositions and recombinations of structure and multiple favorable sources- reservoir-cap combinations in vertical direction.The migration transporting systems in the research area was classified into four kinds:fault form,reservoir form,fracture form,and unconformity plane form.According to oil-gas accumulation characteristic of northwest and northeast area of Sichuan Basin,controlling factors of oil-gas accumulation are following as:(1) the paleo-liftes which controlled the distribution of oil and gas;(2) communication of insidious fault in vertical direction which provided a favorable condition for oil-gas migration and accumulation;(3) reservoir developments which controlled the distribution of oil and gas in the foreland basin;(4) the structural overlay action in later period which accelerated the hydrocarbon reservoir′s evolution.