Method And Application Of The 3-D Deviated Well VSP Ray Tracing

Be aimed at a number of issues in the 3D-VSP seismic exploration, this paper uses iteration segment by segment to realize 3-D deviated well VSP ray tracing. Through numerical tests, not only the availability of 3-D well deviated well VSP multi-wave records, and obtain the distribution of reflection points, superimposed frequency distribution, the incident angle distribution, AVA characteristics and so on. All of these parameters have application value in 3-D deviated well VSP geometry designing, reservoir characterization analyzing and parameter inversion.In this study, three aspects: First, any complex layered media-ray forward modeling methods; the second part is that a complex multi-layered media three-dimensional deviated VSP forward ray-tracing; the third part is analysis and application the parameters of 3-D deviated well VSP multi-wave forward ray-tracing From the Eikonal equation, this paper study iteration segment by segment ray tracing that can adapt to any complex layered media. This method is based on Snell theorem and Fermat's principle .The main idea is by use of one-order Taylor incomplete expansion to expand Travel time equation, and ignore the second entry point to get a computational reflection (transmission point) formula. Starting from an arbitrary given initial ray path, ray-t racing is iteratively calculated segment by segment. The procedure is kept on until the sum of adjustment quantity in the whole path is in the range of precision. Formula contains only include add, subtract, multiply, divide calculated to improve the computational efficiency.In complex multi-layered media three-dimensional inclined VSP forward ray-tracing, through the horizontally layered model, tilted layered model and a random fluctuation layered media model modeling, iteration segment by segment to realize 3-D deviated well VSP ray tracing in the application of results; by using the ray path and the AVA to analyze the method's feasibility and effectiveness in 3D VSP ray tracing forward.3-D VSP ray-trace forwarding can get reflected point coverage of the reflective layer, the number of covering and angle of incidence. These parameters have a significant role on the 3D deviated VSP survey design. By studying the change of the distribution of shot, shot missing, shot distance, depth and distance of receiver points in the purpose of the different depth layers of the P wave and P-SV wave reflection point coverage and frequency of change, provide the basis for three-dimensional deviated VSP survey designing to select the best parameters.Forward ray tracing applications: using P6 QK 18-2 oil field well's 3D observation system, forward the stratigraphic model of this region, and analyze this model's VSP wave field characteristics, and different depth layer's covering of the frequency and incidence angle distribution, and characteristics of the AVA.