The Study Of Prestack Seismic Inversion And Well-posedness Based On T-distribution

Pre-stack seismic inversion is an important quantitative prediction of oil and gas exploration,and it has been widely accepted in the practical exploration.Especially after the method of Bayesian is introduced pre-stack seismic inversion has been developed and applied rapidly in practical application.Bayes inversion is an important manifestation of probabilistic inversion in the current,it can alleviate the problem of uncertainty in the inversion to a certain extent.But the construction of Bayes frame is not objective,especially the prior functions is constructed with experience whether Gauss or Cauchy distribution and even improvement of Cauchy distribution can not accurately sum up all types of strata.According to the restricting factors in the process of construction,we put forward the framework of Bayes based on t-distribution as prior.We demonstrate that the t-distribution is effective for building Bayes framework by contrast,the distribution of model verification and the actual area of inversion analysis.At the same time,we can realize that Bayes inversion based on t-distribution has better applicability and accuracy.For the moment,pre-stack inversion has so many problems that the inversion results have not ideal,especially the high uncertainty,the inaccurate results and unreliable inversion parameters.By calculating the condition number of ill-conditioned matrix,we can get the influence factors of the stability of inversion.We analysis the accuracy of the inversion from the contribution and the characteristic value and the method depend on constraint from the constraint conditions so that we can realize the reliability of the inversion results.We analysis the uncertainty problem of inversion parameters from depending on the geological conditions and Bayes frame construction for theory foreshadowing of the inversion result.Construction of fluid factor is the key step in fluid identification.But on the way of construction method,different scholars have different views.Fluid factor based on the Gassmann equation and the theory of porous media can indicate the reservoir and fluidbetter so that it has been widely used.But the variety of fluid factor and how to adjust the parameter c restricted the development to difficult to popularize and application.Through the analysis and deconstruction of fluid factor,we can get the principle and influence factors about it.Afterwards,we put forward the new fluid factor according to the construction principle and influence factors.The new fluid factor we build not only has clear physical meanings but also has higher sensitivity and accuracy.