Method Research Of Multiscale Seismic Data Modeling And Inversion

Reservoir geophysics is a new discipline that geophysics technique towards the integrated application of oilfield development and production, the reservoir description and reservoir management is included. The geophysics technique is adapted to determin the reservoir, descript the reservoir and monitor the change in the production. It is relying on the development of 3-D high-precision seismic technique, borehole seismic technique, time-lapse seismic technique and multi-wave/multi-component technique, the integrated research of high-precision 3-D seismic and other methods is the key technology of reservoir geophysics. Research the modeling and inversion method of multiscale seismic data is improving the capacity of seismic data to resolve the geology problem. Develop the high precision seismic modeling method of wave-equation in viscoelastic media, determine the mulitscale seismic response characteristics of geology with different observation system. Build up the multiscale seismic data joint inversion method based on the Bayes theory, overcome the multiple solution of inversion problem and improve the resolution of seismic data inversion, then service for the oilfield development with seismic data.The nature attenuation law of seismic propagating in actual media is very complicated. many attenuation model of attenuation model is present in theory. The approximation to Q is obvious to most models in seismic wave-equation modeling at viscoelastic media in time domain. Based on the rheology theory, the adaptability of SLS (Standard Linear Solid), Kelvin and other attenuation model is researched in viscoelastic seismic modeling. The generalized rheology models that can be use to accurately describe the seismic wave propagating and attenuation characteristics have been analysied, the equivalence of generalize Maxwell model and generalized SLS model is proofed. The fitting degree to the constant Q of different order generalized Maxwell model is analysized and compared with the Futterman model and other models, the foundation is perfecing to modeling the constant Q characteristics in viscoelastic media. One dimension plane wave modeling is done with these attenuation models, the difference of seismic wave propagation and attenuation characteristic can be inteprated with these results, the advantage of generalized rheology model is clear.The generalized rheology model is used in wave-equation seismic modeling at viscoelastic media in time domain. For the generalized Maxwell model, two kinds of unelastic function is adapted to derive the wave-equation. The unelastic modulus and relaxed modulus have been used to build up the wave-equation for generalized SLS model. The unified expression between these two kinds of generalized rheology model after the memory variable is redefined. The expression of displacement equation, the displacement-stress equation, the displacement-velocity-stress equation and the velocity-stress equation is presented according different modulus form.With the equation expansion or variable transform, the commom viscoelastic wave equation in articles can be get, the disadvantage of early equation expressed by relaxed modulus is clear. The high-order staggered grid finite difference scheme of high-precision viscoelastic wave equation based on five-order generalized Maxwell model is present. It is the high-precision wave-equation modeling method to constant Q in viscoelastic media. The PML boundary condition is used to absorb the artificial boundary reflection, the stability condition and source problem is discussed, the high-order finite difference scheme is accurate enough according to the comparison with the analytical resolution of 2D homogeneous viscoelastic media.According the high-precision viscoelastic modeling, the attenuation and dispersion characterstic of seismic wave is obvious in viscoelastic media. With the Q decrease and the propagation distance increase, the amplitude is attenuated. the phase is lagged. the dominant frequency is decreased. Modeling with different observation system and compare with the wave field, common shot gather and migrated section characteristic, the relationship and difference among multiscale seismic data can be recognized. The relationship is multiscale seimic data is the seismic wave reflection response of the same geological body under different observation way. The difference is represented at the wave field information richness, the geological range and the detail characteristic in the multiscale seismic data. When the near-surface strong attenuation layer is considered, the phase difference is obvious between surface seismic data and others, the relationship and difference among multiscale seismic data can be inteprated.Based on the Bayesian theorem, the new likelihood fundction is integrated with surface, vsp and crosswell seismic data, the multiscale seismic data joint inversion framework is built with modified Cauchy distribution and the inversion flow is improved. The one-dimension model testing shows that the method is right, the chi-square distribution is used to select the parameter range of the joint inversion with gauss noise, the joint inversion flow is valid to the two-dimension multiscale seismic data modeling according to the wave equation. For the singlescale seismic data, the crosswell seismic data inversion workflow in depth domain is improved. The high-precision interpolation function was adapted in depth-time transformation, the reflection characteristic consistence between surface seismic data and crosswell seismic data is emphasized, the transverse constraint is strengthened according to the characteristic of multi-crosswell seismic data.The multiscale sesmic data inversion method is tested in Ken71 area of Shengli oilfield. The reasonable inversion result of multi-crosswell seismic data is get, the pseudo well exracted from it can mathch the characteristics of surface seismic data well. The constraint inversion with pseudo well can improve the precision of result. The multiscale seismic joint inversion method can reduce the multiplicity of solution, improve the inversion resolution, the multiscale data can be matched with each other according to the joint inversion result.