Abstract:

The fractured gas reservoirs in east Sichuan,no matter they are anticline traped ones or structural fracture pinch traped ones,are all controlled by tectonic deformation.The hydrocarbon enrichment is closely ralated to Himalayan tectonic evolution.The tectonic evolution of the present region in Himalayan orogen has always been disputed,and the division of formation stages differs from each other.Therefore,the evolution in hydrocarbon-bearing structurs may also be different.In application of structural geometric and directional filter analysis,the structures can be divided into four fold sys-tems in this paper according to the folds strikes,the dipping direction of pivots,the closure,cross-sectionpattern,amplitude and depth of folds as well as the configuration on sterographic projection map.Then the evolution of these folds is divided into four generation based on the alternative relationship of big and medium sized folds and the displaced fabric type of the pivots of small sized folds.The distribution and superim position of the fold systems in south,north and central blocks differ greatly from each other due to the control of two northwest strike basement rifts.Through rebuilding tectonic evolution history,the authors consider that,traps formed earlier havethe priority to trap oil and higher enrichment,conversely,the enrichment may low;synclines that up-lifted higher in amplitude and emerged older in strata may have poor preservation condition,otherwise,the condition may good.Exploration in this area has proved that the ratio of success can reach 75% for the wells located according to the above mentioned.