Study On Relationships Between Salt-Mud Tectonics And Hydrocarbon Migration And Accumulation In Dongying Depression

Salt-mud tectonics is the most important structure for hydrocarbon accumulation in theDongying Depression. It is necessary to research on salt-mud tectonics in both theoretically andpractically. This work is supported by National Natural Science Foundation of China (NSFC).Guiding with new theories and methods on salt tectonics and mud tectonics, basin-fluid analysis,hydrocarbon migration and accumulation, the thesis focus on studying the relationships betweensalt-mud tectonics and hydrocarbon migration and accumulation, which is also a charming andchallenged theme at home and aboard. Firstly, the paper proposes the concepts of the salt-mudbed and salt-mud tectonics. Then the styles, characteristics of spatial distribution, geneticmechanics and evolution of salt-mud tectonics are refined in the Dongying Depression. Based onwhich the paper discussed the controls of salt-mud tectonics on hydrocarbon migration andaccumulation and their mechanics, subsequently established fluid dynamic system model ofhydrocarbon migration and accumulation related to salt-mud tectonics. Finally, the prospects ofpotential reservoirs are proposed related to the salt-mud tectonics. 1. The typical feature of primary sediments of saline sequence in the Dongying Depressionis the rhythmic succession characterized by interbeds of evaporite and overpressured mudstone,which is prevalent in continental fault basins in China. So the concepts of salt-mud bed andsalt-mud tectonics are proposed in this paper. Salt-mud bed refer to sedimentary sequencesconsisted of the interbeds of evaporite and overpressured mudstone, which has the ductile orfluid properties. Salt-mud tectonics is one kind of tectonics resulted from the distortion ofsalt-mud bed flow. Salt-mud tectonics is different significantly to pure salt or mud tectonics. 2. Based on the seismic profiles with seismic net spacing in almost 2km, the salt-mudtectonic styles in the Dongying Depression defined in this paper include salt-mud pillow,salt-mud roller—detachment fault family—rollover anticline, and salt-mud core anticline—keystone fault family. According to the spatial distribution features, the conventional CentralUplift Zone is re-divided into three subtectonic zones. They are the northern zone ofsalt-mud-core anticline and keystone fault family (Dongying tectonic zone ), the middle zonecomposed of salt-mud pillow, detachment fault family and rollover anticline ( Xinzhen andHaojia tectonic zones ), and the southern zone composed of salt-mud roller, detachment faultfamily and rollover anticline (Shinan-Xianhezhuang and Liangjialou tectonic zone). 3. The trigger mechanism of the salt-mud tectonics is the gravitational gliding withinregional extension. Salt-mud bed accumulating and upwelling and thin-skinned detachmentincarnate gravitational gliding. Consequently, the evolution of salt-mud tectonics is divided intotwo stages composed of salt-mud pillow developing stage (Before SB6') and detachment fault,salt-mud roller and salt-mud-core anticline developing stage (After SB6').4. Combined acoustic logs and drill stem test (DST) data, structure of pressure system arecomplied on wells, profiles and planes, all of which indicate that a huge source rock –overpressure compartment complex (SR-OPCC) exist in the Dongying Depression. The activesource rocks in third-forth member of Shahejie Formation and Kongdian Formation constitutethe main body of SR-OPCC. And two systems can be divided as overpressure fluid dynamicsystem and hydrostatic-under pressured fluid dynamic system respectively. The overpressuredexpulsion and overpressued transference are discussed dramatically in this thesis, which isregarded as the "gold key" in understanding basin fluid flow and hydrocarbon migration andaccumulation. 5. Saline fluids are defined as the fluids with Total Dissolution Solidity (TDS) over 10g/l inthis paper. There are three kinds of saline fluids including lower salinity fluids (10