Accumulation Conditions of Hydrocarbon Generated by Marine Source Rock in Southern Depression of Southern Yellow Sea Basin

Abstract

The energy situation of China has been very tough. Our country’s oil is heavily dependent on imports and lack of oil and gas reserve. The shortage of oil and gas resource has become an important factor which restricts our national economy health and sustainable development. Guided by the theory of petroleum system, we analyzed the Mesozoic-Palaeozoic marine strata hydrocarbon accumulation elements and conditions of the sourthern depression in Southern Yellow Sea Basin and concluded the hydrocarbon accumulation pattern in order to find the reserving oil and gas. There are seven source-reservoir-cap assemblages. Different tectonic units experienced different tectonic evolution history. The source rock of Lower Palaeozoic, Upper Palaeozoic and Lower Triassic have experienced four, three and two hydrocarbon generation stages separately in the depression. But the source rock of Lower Palaeozoic and Upper Palaeozoic in the salient have only experienced two and one hydrocarbon generation stages separately. Hydrocarbon generated by Mesozoic-Palaeozoic source rock migrated to the traps by fault, crack and unconformity. Lithologic trap, broad anticlinal trap and fault-lithologic trap are the main types in the study area. By the analysis of Mesozoic-Palaeozoic marine hydrocarbon accumulation in the sourthern depresssion, we concluded two accumulation patterns which are the original lithologic reservoir in the Mesozoic-Palaeozoic marine strata and fault-lithologic reservoir in the Mesozoic-Cenozoic terrestrial strata. These results will help to predict the oil and gas resources.