Hydrocarbon accumulation conditions analysis of Cretaceous reservoirs in southern Liupanshan basin

Liupanshan Cretaceous basin is one of the most important exploration strata and there are more hydrocarbon shows in lower Cretaceous in the south,which shows a good exploration potential in this area.Through analysis and evaluation of hydrocarbon accumulation elements such as hydrocarbon source rocks,reservoir-cover features,trap,hydrocarbon migration and accumulation history,the controlling effect of these geological elements on hydrocarbon accumulation has been clarified.The results indicate two sets of source rocks,namely the middle member of Liwaxia formation and Madongshan formation from lower Cretaceous in southern Liupanshan basin,are considered to be capable of generating hydrocarbon.Two sets of reservoir-cap assemblages have been developed,among which the reservoir is characterized by low porosity and low permeability,superimposing with source rocks and large gross thickness.Influenced by the tectonic activities,two phase of hydrocarbon filling have occurred in late Cretaceous and late Oligocene.The matching relationship among different accumulation elements is reasonable,the paleo-oil reservoir in weakly reworked area and complete structural traps in intensely reworked area are the most favorable targets for further exploration.