Hydrocarbon Forming Regularity And Exploration Potential Evaluation In Nanyang Depression

From the tectonic movement, deposition evolvement and their space-time allocation relationship in Nanyang Depression, the basin settlement history, petroleum structure analysis and other technologies and theories were adopted to analyze the formative mechanism of Nanyang Depression, movement period of rifting, characteristics of faults distribution, deposition evolvement feature and the space-time allocation relation between deposition and tectonics in the North Slope of Nanyang Depression.Taking full advantage of hydrocarbon forming theory, the analysis on hydrocarbon forming dominant factors and space-time configuration of reservoir formation process in Weigang, Zhangdian, and Dongzhuang oilfields in Nanyang Depression, the discussion on hydrocarbon migration accumulation mechanism, generaliztion of hydrocarbon forming modes, as well as prediction of reservoir geological feature and enrichment regularity are carried out.The pathway of hydrocarbon migration focused on the ridge of carrier bed is analyized. Two types of carrier-ridge, nose-like structure and lithology, as well as anticline-lithology, are mainly appeared in Nanyang Depression; the carrier-ridge of nose-like structure and lithology appeared in the area of Weiguang, Beimazhuang, and Zhuangdian, the carrier-ridge of anticline-lithology located in Dongzhuang Depression. The carrier-ridge is characteristics of obvious succession, which controls hydrocarbon migration and accumulation in Nanyang Depression, and indicates that the direction of carrier-ridge is the pathway of main hydrocarbon migration.The analysis on the types, dominant factors, and distribution rules of reservoirs in various tectonic provinces is conducted. The reservoirs in Nanyang Depression are mainly distributed in maturation zone and boundary of source rock on the plane, and mainly distributed in H2 and H3 Members on vertical direction; the reservoir is the oil & gas assemblage of self-generation and self-accumulation. The key dominant factors are tectonic units (northern slope, central depression and southern fault overlap zones), and lithologic assemblage and source reservoir cap rock assemblages as well. Various reservoirs are distributed in different positions in the three structural zones; the faulted nose, faulted block and fault–lithology reservoirs mainly distributed in northern slope zone, the faulted nose, faulted block and fault–lithology reservoirs distributed in central depression also, while the anticline, faulted anticline and up-dip pinch out reservoirs mainly distributed in southern fault overlap zone.Hydrocrbon forming regularity in Nanyang Depression is generalized systematacially, and the assemblage modes of Weigang, Zhangdian, and Dongzhuang oilfields are built. The reservoir-forming in Weigang oilfield is fault-nose and fault-block mode of vertical migration accompanied with lateral migration, and hydrocarbon maturation and enrichmententral controlled by fault, namely, the fault effects on vertical connection; The reservoir-forming in Zhangdian oilfield is fault-nose mode of lateral migration and fault seal, namely, the fault effecting on vertical connection is limited ; The reservoir-forming in Dongzhuang oilfield is fault-anticline mode of vertical migration and fault transection.Focusing on the topic of hydrocrbon forming regularity in Nanyang Depression, the techonic mechanism in the depression is improved further, the migration and accumulation mode is built, the evaluation and describtion of exploraion targets on the basis of divided zones are implemented, and therefore the future exploration in Nanyang Depression is designated.