The Geological Structures In The Northern Slope Of Gaoyou Sag And Their Constraints On Petroleum Accumulation

The Northern Slope of Gaoyou Sag is one of the important and difficult exploration area in Jiangsu Oilfield. This thesis analyzes the structural features and the hydrocarbon distribution of the Northern Slope of Gaoyou Sag, further discusses the controlling of structures to oil and gas reservoir, and be able to provide more beneficial help in exploration of the research area.Aiming to geology features of complex fault-block, this thesis successively studies Subei Basin, Gaoyou Sag and Northern Slope according to the comprehensive application of geology, seismic interpretation, drilling and well log data, and under the guidance of Structural Geology, Petroleum Region Analysis, Petroliferous Basin Analysis and Petroleum Geology, and the geometry, kinematics, dynamics and time are also taken into consideration. The main contents includes structural evolution stages, structure styles and their origin of Subei Basin; structure and geometry features, reservoir types and genesis and accumulation model of Gaoyou Sag; characteristics of regional structures, faults and fault assemblages as well as structural trap belts and their genesis of the Northern Slope. The thesis summarizes the controlling of structures to the distribution of oil and gas, and search for favorable structural traps.Main conclusions are as followings: There are four structure styles developed in Subei Basin, such as extensional structure style, strike-slip structure style, compressional structure style and reverse structure style, which formed in the same strike-slip extensional stress field; The traps of Gaoyou sag can be divided into four types such as structural traps in Northern Slope, fault-block traps adjacent to main faults, fault nose traps and block traps developed at the transfer zone which occurs at the intersection part of the main control faults, complex fault-block traps in South Terrace, and the dominant reservoir-forming factors of different petroleum accumulation are different; The Northern Slope of Gaoyou Sag can be divided into four regional structure belts, such as Chian structure belt, Matouzhuang structure belt, Xiejiazhuang-Shanian-Wazhuang structure belt, and Wuchahe structure belt, numerous faults developed in the Northern Slope of Gaoyou Sag but their scale is small and length is short and so their vertical fault throw is also very small; The fault is the main control factor of petroleum accumulation, and the controlling mainly manifested in the following five aspects: the fault size, the matching relationship of fault active stage and petroleum accumulation stage, fault stress state, lateral barrier of antithetic faults, fault shape and fault combination. Guided by structural traps and petroleum distribution characteristics in Gaoyou sag, put forward four favorable structural traps such as zones adjacent to Liuling Fault and the southern slope of Linze Sag as well as the structural traps controlled by Fudong Fault and its sub-faults on the slope of Hai'an Sag. Compared to references existed, this paper brings innovation in stucture styles and their genesis of Subei Basin, and stucture trap belt divisions and their genesis of Gaoyou Sag.