A Study On Seismic Scattering Wave Imaging Method

The scattering wave seismic exploration method is proposed for solving the challengesand problems exposed during the reflection wave exploration method in complex geologicalconditions. The scattering wave is a generalized seismic waves, which can be used to describeany form of seismic waves, and the producing conditions of seismic scattering wave arewidespread. Therefore, using the scattering wave to study the geological problems hasimportant practical significance and application prospects. Besides, its theoretical and appliedtechnology research are forefront subjects in the field of seismic exploration. This papersummarizes and researches the theory and the development status of application of seismicscattering wave, and studies the scattering wave imaging technique systematically by usingthe Common Scattered Point(CSP) gathers based on the concept of equivalent offset as thestarting point.1) The Common Scattering Point(CSP) gathers based on the concept of equivalent offsetis a new gather, which accumulates energy may come from the same scattering point of alltraces. It has a higher fold numbers and greater offset range, less dependence on the velocityfor its formation and the natural anti-aliasing and strong anti-noise ability, making it suitablefor seismic data imaging with low signal-to-noise ratio and abundant scattering energy. Thispaper systematically studies the forming principle of CSP gathers based on the equivalentoffset, deduces detailedly and gives the formula related to the mapping of CSP gathers.Particularly, the author derived the equivalent offset defined formula of rugged topographyand vertical receiver array (such as VSP, Cross-well seismic, etc.); gave the fast mappingalgorithm for the CSP gathers in several cases at length; analyzed and compared thecharacteristics between the CMP gathers and CSP gathers through several typical models;analyzed the factors affecting the CSP gathers in detail.2) CSP gathers and CMP gathers are both multi-fold seismic gathers that are consistentwith a hyperbolic law. In this papers, the velocity analysis method of CMP gathers is appliedto the CSP gathers and the velocity analysis flow of CSP gathers is summarized. Ultimately,relying on the typical model, the paper compared and analyzed the velocity spectrum andvelocity field of these two gathers, which finally proved that the velocity analysis of CSP gathers is not affected by the impact of the dip angle of strata, and the velocity modelacquired reflected the true velocity structure of the geological body.3) This paper studied three kinds of scattering wave imaging methods based on CSPgathers, and established the flows of scattered wave imaging. These three imaging methodsare based on the Kirchhoff integral principle. Among them, the equivalent offset migrationmethods is of stronger adaptability, which is suitable for the level and the rugged topography.CSP gathers formed by the surface array and vertical receiver array are with strongeranti-jamming capability. The common equivalent point stack and poststack migration imagingmethod is only suitable for the CSP gathers formed by level topography of surface array, intheory this imaging is better than the equivalent offset migration methods, but of worseanti-noise ability. Based on prestack migration method of CSP gathers is a new kind ofscattered wave imaging method proposed in this paper, which is only suitable for leveltopography of surface array; In theory, this approach combines the advantages of the twoprevious ones and avoids their shortcomings. Finally, related imaging methods were tested byusing model datas and actual datas to obtain more satisfactory results than throughconventional reflective wave imaging methods and also found some problems for furtherresearch.