The Research Of Integrated Technology Of Seismic Inversion And Rock Physics Inversion

The prediction of reservoir parameters is an important content of seismic reservoir characterization.Even though the inclusion model is suitable for tight reservoir,inclusion model is rarely used in rock physics inversion because of complicated mathematical formation and strongly nonlinear.In order to invert out reservoir parameter,the elastic parameter need to be used as the input data of rock physics inversion.So,the integrated research of seismic inversion and rock physics inversion is a highlight in the current research.Considering the research statement and practical requirements,the integrated technology of seismic inversion and rock physics inversion has been research in this dissertation.The following subjects was researched in detail:First,the thesis constructed a rock physics modelling for tight-middle porosity and permeability reservoir.Based on comparison between different models,the inclusion model,which could consider influence of pore volume and structure on elasticity,is suitable for tight reservoir rock physics modelling.By model testing,this rock physics modelling method fits for tight sandstone reservoir,tight carbonate rock reservoir with multiple pore types,and anisotropic tight sandstone reservoir.Second,in order to use inclusion model in rock physics inversion,trust region approach was used in rock physics inversion which could cover features like complicated mathematical formation,strongly nonlinear and iterated computation.The constrained least squares method was used to denoise outlier noise.By model testing,the rationality and feasibility was confirmed.For Gaussian noise,constrained least squares could improve inversion stability.When only 2 elastic parameters could be used as input of rock physics inversion,the features of quantitative of inversion becomes weak but the reservoir parameters could still describe the good reservoir which is with relatively low volume of clay and high porosity.Third,the usual pre-stack inversion method is weak on stability and resolution of density.In order to provide density as input of rock physics inversion,Cauchy distribution and scale matrix were used in prestack sparse spike inversion to improve density quality.Comparing with Gaussian distribution,Cauchy distribution has narrower peaks and longtailed distribution,which are more consistent with real distribution of reflection and fast convergence during inversion computation.By projecting statistically correlated Vp,Vs and density reflectivities to independent variables through SVD of covariance matrix,the resolution of elastic parameters,especially density,could be improved.Fourth,the integrated technology has been used in a field research in which reservoir is typical lithology reservoir.By prestack sparse spike inversion with Cauchy distribution and scale matrix,the inverted elastic parameters could consist with the real ones on wells.The inverted reservoir parameters from rock physics inversion are consistent with the real ones and the distribution of clay volume and porosity could describe the reservoir distribution in space.By this real field application,the rationality of method was verified.