构造几何分析在川东油气勘探中的应用

THE APPLICATION OF STRUCTURAL GEOMETRIC ANALYSIS TO HYDROCARBON PROSPECTING IN EAST SICHUAN

川东地区的裂缝性气藏,均受构造变形特征所制约。作者应用构造几何分析与定向滤波分析相结合的方法,将本区构造划分为四个褶皱系和四个世代,均属喜山期形成。并认为:形成早的构造(圈闭)气藏富集程度高,反之则低;隆起幅度高、出露地层老的背斜气藏的保存条件差,反之则好。按此法部署探井的构造,钻探成功率达75%。

The fractured gas reservoirs in east Sichuan,no matter they are anticline traped ones or structuralfracture pinch traped ones,are all controlled by tectonic deformation.The hydrocarbon enrichment isclosely ralated to Himalayan tectonic evolution.The tectonic evolution of the present region inHimalayan orogen has always been disputed,and the division of formation stages differs from eachother.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.Thenthe evolution of these folds is divided into four generation based on the alternative relationship of bigand medium sized folds and the displaced fabric type of the pivots of small sized folds.The distributionand superimposition of the fold systems in south,north and central blocks differ greatly from eachother 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.