Application Of Anti-dispersion Reverse Time Migration In Dongpu Depression

Dongpu depression has the geological features of complex structure,broken block,thin reservoirs,rapid change and small reservoir height.Currently,there are mainly following geological problems in exploration and development : Complex faulted blocks are poorly imaged,small block traps are inaccurate,signal-to-noise ratio and resolution can not meet the requirement of lithologic reservoirs exploration,and special lithological reflectance has a great influence on the imaging of the underlying strata.The seismic data quality Poor,buried in the Paleozoic buried imaging unclear.The above problems bring some difficulties to the interpretation and research of the Dongpu depression structure and lithologic traps.In view of the current high-precision seismic data,a new anti-dispersion reverse time migration technology is used to improve the seismic data accuracy and effectively improve the exploration problems in Dongpu depression.Conventional reverse time migration method uses the finite difference operator for wavefield propagation.Due to the influence of the numerical dispersion,the high frequency part is lacking and the imaging frequency band is limited.Based on the original reverse time migration method,the finite difference coefficients and the parameters of reverse time migration are optimized.The anti-dispersion reverse time migration method proposed in this paper has better anti-dispersion effect,can better retain the signal of high-frequency components,improve the resolution,in order to achieve high-precision 3D exploration Dongpu depression,and meet the need of high-precision seismic imaging exploration.The newly proposed anti-dispersion reverse time migration method is tested in two ways:a complex salt model and a shengli grit model,a complex salt model created by the true structural features of the Gulf of Mexico where high-velocity rock mass with high steepness has been a difficult imaging problem.This test mainly tests the advantages of anti-dispersion reverse time migration in high-steep structures,high-speed salt imaging and sub-salt faultblock imaging.Due to the presence of high-speed fault blocks,deep illumination in the imaging process of Shengli grit model will be insufficient,combined with strong lateral speed changes and unobvious fault block boundaries,which make it more difficult for high-precision seismic imaging.After testing,it can be seen that the improved anti-dispersion reverse time migration has less noise and higher resolution than the original method in the imaging results,the structural features are clearer and the imaging effect is improved.After the model test,the anti-dispersion reverse time migration method is applied to the actual data processing in Dongpu depression.Comparing the results before and after the processing,we found that the anti-dispersion reverse-time migration method solves the existing problems in the exploration and development of Dongpu Depression effectively.