Research on the Structural Characteristics and Fault Sealing of the Northern Fault Zone in Depression A

The P oil layer in the S block of A sag developed shallow water delta deposition, which formed the thin interbedded sand and mudstone. After long-term water flooding development, it has been in the high water cut stage, and the remaining oil is scattered. The remaining oil at the edge of the fault can be used as an important potential tapping object in the later stage. It is necessary to consider the width of fault fracture zone and fault sealing when determining the safe distance of well location deployment and optimizing the potential area of well deployment. Based on core, logging and seismic data, the internal structural characteristics of faults in the block are studied. It is confirmed that the fault zone of sand-mudstone thin interbedded strata in the study area has a dual structure of fault core and fracture zone. Mudstone smear is developed in the fault core, mudstone fractures and sandstone deformation zones are developed in the fracture zone. The width of the fault fracture zone is positively correlated with the fault distance. It is predicted that the width of the fault fracture zone is generally less than 15 m. The fault gouge ratio (SGR) method is used to quantitatively evaluate the lateral sealing of the fault. The virtual well is used to calculate the shale content in the absence of wells at the edge of the fault. The shale content of the virtual well is obtained by the well-seismic joint inversion method, which ensures the fine and reliable evaluation of the fault sealing, and clarifies the sealing ability and difference of the fault in different parts of the plane and vertical direction. In response to the research needs of tapping the remaining oil at the edge of faults in high water cut blocks of old oil fields for the study of internal structural characteristics and fault sealing, the focus is on conducting research on the internal structure and characterization of fault zones, quantitative evaluation of fault sealing, etc., to achieve quantitative characterization of the internal structure and fault sealing of sandstone mudstone thin interbedded faults, which has significant guiding significance for the deployment of well positions at the edge of faults.