| Slip fracture is a special and mechanically complex fracture system in sedimentary basins,which has the dual role of blocking and transporting,and is crucial for oil and gas transportation and reservoir formation as well as preservation.The Mo-Yong area of Junggar Basin is located in the abdomen of Junggar Basin and is influenced by the complex tectonic action of the periphery,and the slip fractures are developed.The degree of oil and gas enrichment varies from slip fracture zone to slip fracture zone,and different parts of the same slip fracture zone contain different oil.To address the above-mentioned problems,this thesis is guided by the basic theories of tectonic geology,fracture hydrocarbon control theory,petroleum geology,etc.Through the interpretation of seismic data,field geological investigation,core observation and description,and systematic collection of samples for analysis and testing,a fine description of the spreading of the strike-slip fractures and their internal structure in the study area is made,and the fracture closure is clarified through a comprehensive multi-factor fuzzy evaluation,combined with the analysis of oil and gas reservoirs in typical strike-slip fracture zones,a comprehensive reservoir formation model of the study area is finally established,and the reservoir control significance of the strike-slip fractures is clarified.The results of the study show that:(1)The study area is influenced by the circumferential tectonic movements and has complex tectonic stress and fracture characteristics.According to the scale and characteristics of fracture development,the fractures can be divided into three types: main faults of floriform faults,branch faults of floriform faults and isolated intra-stratigraphic low-order faults.The profile combination style is mainly flower faults and "y" faults,but there are also steeply dipping upright faults,and five combination styles of parallel,oblique intersection,broom,comb and grid are mainly developed in the plane.According to the results of tectonic evolution,the study area can be divided into three stages of fracture evolution.(2)By observing the outcrops of fracture zones in the field,a binary structural model of sliding fracture zone and induced fracture zone in the strike-slip fracture zone is established,and on the basis of this model,data from cores and logs of typical wells are used to comprehensively divide the structure of fracture zones in the study area.The pore-permeability tests and microscopic characteristics of field samples and core samples reveal that the permeability of fault mud in the sliding fracture zone is lower than that of the original rock,which is the key factor to determine the closure,and the permeability of the induced fracture zone is related to the magnitude of its diagenesis.The key factors affecting the structural development of the fracture zone are summarized in the above studies.(3)Based on the anatomy of the fracture zone structure in the field and in the study area,four mechanisms of lateral fracture closure are clarified,five closure factors are preferentially selected,and the fuzzy comprehensive evaluation method is used to evaluate the closure of the main control faults in the study area.The evaluation results show that the near-east-west fault closure in Yongjin area is the best,the near-north-south fault closure is poorer,and the transmission and conduction are the main factors,and the overall fault closure in Moxizhuang area is poorer than that in Yongjin area.Finally,combined with the typical reservoir anatomy,it is clear that the study area has a good matching relationship between fracture transmission and conduction and oil and gas transport and accumulation formation,and the fracture has a certain controlling effect on oil and gas distribution. |
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