HYDROCARBON PRESERVATION ANALYSIS FOR MARINE STRATA IN SUPERIMPOSED BASINS OF CHINA

The formation and evolution of superimposed marine basins in China usually experience two main stages: the formation stage and the reconstruction stage. Tectonic movements determine the difference of hydrocarbon accumulation and preservation conditions of the marine strata in the basins. Architecture of the basin-mountain systems formed by the basin and its surrounding orogenic belts determine the superiority and inferiority of the oil and gas preservation conditions. Gypsolyte/saline rocks and shales are the two major caprocks in superimposed basins, and the sealing effectiveness of caprocks in the multi-stage tectonic changes is an important condition for oil and gas preservation.The temporal relationship between magmatic activity and hydrocarbon generation as well as migration is closely related to hydrocarbon preservation. Hydrogeochemical and paleo-fluid geochemical characteristics of groundwater can be used as the indexes for evaluation of oil and gas preservation conditions. The simulation of oil and gas accumulation and escape provides a new idea for the quantitative study of oil and gas preservation conditions. The concepts of oil and gas preservation unit and preservation system and related evaluation system can properly reflect the partition of hydrocarbon preservation conditions. Upon the basis of regional tectonic evolution to evaluate the hydrocarbon preservation conditions through multiple perspectives of marine strata in superimposed basins, has been improved of an efficient performance for trap selection and exploration strategy determination for marine oil and gas accamulations.