| Fault is an important geological structure,which largely determines the distribution,migration and storage of oil and gas.Therefore,it is very important to identify faults accurately in the field of seismic image processing.However,most fault identification methods are data-driven and do not consider the geological laws and structural features contained in seismic images,which are prone to be interfered by noise in the processing process and often fail to achieve the expected recognition effect.In this thesis,based on the theory of geology and seismic exploration,the direction and structure information of geological structure are extracted from seismic images,the geological pattern constraint mechanism is summarized,and the 3D seismic fault identification method with geological pattern constraint is formed.The work is mainly carried out in the following aspects:1.Combined with geology and seismic exploration theory,two kinds of geological pattern constraint mechanisms are summarized from the formation law and structural characteristics of different geological structures: one is the stratigraphic pattern with the direction information and structural characteristics of strata as the main content;The other is the fault pattern with the planar linear structure of faults as the main content,which plays an important role in seismic data processing and fault attribute extraction.2.Under the constraints of geological pattern,seismic data are processed by vector median filtering and anisotropic diffusion filtering,and seismic data volume with enhanced fault features is obtained.By constructing and decomposing the structure tensor of seismic data,the direction and structure information contained in seismic data are obtained,and the geological pattern constraint conditions are formed,which are introduced into vector median filtering and anisotropic diffusion filtering.By comparing the data before and after filtering,it can be seen that the seismic data noise is suppressed effectively by the vector median filtering constrained by geological pattern,and the signal-to-noise ratio of seismic data is improved.Anisotropic diffusion filtering with geological pattern constraint realizes filtering processing with different intensity in different structural directions.It not only enhances the resolution of seismic reflection in phase axis,but also protects the discontinuous information such as fault,which is beneficial to the subsequent extraction of fault attributes.3.The fault likelihood attribute is obtained by geological pattern semblance,and enhanced by tensor voting technique,and more complete and continuous attribute image of fault structure is obtained.Based on the traditional semblance attribute,the semblance attribute of geological pattern constraint is obtained,and the discontinuous information such as fault is accurately described.In order to further highlight the linear structure characteristics of faults,the fault likelihood attribute is obtained from the semblance of geological pattern,and the fault is described more clearly and accurately,but there are still some problems such as poor continuity of linear structures.Therefore,tensor voting technique is used to enhance the image of fault attributes,which improves the integrity and continuity of the linear structure of the fault.Through experimental comparison and analysis,the enhanced fault attribute image can effectively weaken the "stepped" segmentation of the fault,make the linear structure of the fault more complete and continuous,and improve the imaging quality of the fault image.In this thesis,the orientation and structure information of important geological structures such as strata and faults are extracted from seismic images,forming geological model constraint mechanism.On this basis,fault feature enhancement and attribute extraction are carried out for seismic data,which effectively suppress noise interference,improve the accuracy of fault identification,and make it more consistent with geological laws and characteristics. |
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