Seismic Attribute Analysis Of Diffraction Wave Of Carbonate Fractured Reservoir

At present,with the continuous progress of oil and gas exploration technology,the prospecting direction will turn to unconventional oil and gas exploration and residual oil exploration.Carbonate reservoirs in China contain a large number of oil and gas resources.Most of these reservoirs are fractured-vuggy reservoirs and fractured-vuggy reservoirs,which are widely distributed in superimposed basins.In seismic prospecting,diffracted waves often occur in faults or pinches,often submerged by the strong energy of reflected waves.When migrating and relocating,they are rejected as interference waves,which is not conducive to reflecting small-scale anomalies.In seismic data,the seismic profile of carbonate fractured-vuggy reservoir is beaded,and the small-scale anomalous body is clearly depicted by the diffraction wave.The diffraction wave can be separated and the information provided by it can be fully utilized to reflect the geological anomalous body.This is an important research direction for detecting small-scale anomalies in seismic exploration.The purpose of this paper is to analyze the attributes of the diffracted wave,and to obtain the general rules of the diffracted wave in the characterization of small-scale geological bodies such as holes,cracks and karst caves.Shuntuo area is chosen as the research area in this paper.The pore,fracture and karst cave are well developed in this area,and the geological conditions are changeable.Based on the conventional imaging data of carbonate fractured-vuggy reservoir and the separated imaging data of diffraction wave,the seismic attributes of the data are compared and analyzed.Firstly,the fractured-vuggy carbonate reservoir is studied,the reservoir space and types are summarized,and the formation process of pore and Fracture-vuggy reservoirs with different scales as the main reservoir and the differences between different reservoirs in spatial distribution and spatial morphology are understood.Then,through stratigraphic framework model and fracture Combining the method of cavern medium,the forward modeling and diffraction wave separation of fractured-cavern reservoir model are established,and then the diffraction wave is separated from the actual seismic data after well data analysis,well seismic calibration,structural interpretation,etc.The conventional imaging and diffraction wave imaging of the reflection wave of the three-dimensional model data and the three-dimensional actual seismic data are carried out.Through analysis and comparison of different time slices and data along layers,it is found that the coherence and curvature attributesin diffraction data are more accurate in describing small-scale cracks and underground anomalies,and the reflection wave retains 25% of the data to give consideration to both continuity and detail and better reflect the plane distribution characteristics.The inversion experiments of two-dimensional fracture-cave model show that the results of constrained sparse pulse inversion can only invert a large set of continuous stratigraphic interfaces,but can not invert the karst cave shape.The results of recursive inversion can not reflect the continuous stratigraphic interface,but can invert the details of karst caves and other small geological bodies.As far as inversion results are concerned,recursive inversion is better than constrained sparse pulse inversion in describing irregular geological bodies.Combining the diffraction wave information with the reflection wave information,the imaging accuracy of carbonate fracture and cave body and micro-fracture can be improved obviously,and the underground structure can be described more accurately,which is conducive to the prediction of carbonate fracture-cave reservoir.