Shale gas reservoir brittle seismic prediction method and device

Abstract

The invention provides a shale gas reservoir brittleness earthquake prediction method and device. The method comprises the following steps: carrying out calculation by means of the generalized linear inversion thought, based on a Bayesian theory and by utilizing actual seismic data of a work area and a prior distribution function and a Zoeppritz equation of a plurality of elastic parameters, to obtain a disturbance quantity solution expression of the elastic parameters; carrying out calculation according to the solution expression and an initial model of the elastic parameters to obtain disturbance quantity value of the elastic parameters; carrying out calculation according to the disturbance quantity value and the initial model to obtain a current model of the elastic parameters; carrying out calculating based on the actual seismic data, the current model and the Zoeppritz equation of the plurality of elastic parameters to obtain seismic inversion residual error; and if the seismic inversion residual error is smaller than a set threshold value, serving the current model as the value of the elastic parameters, and carrying out calculation according to the value of the elastic parameters to obtain shale gas reservoir brittle index of the work area. The method and device can improve shale gas reservoir brittle index predication accuracy.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a shale gas reservoir brittle seismic prediction method and device. Background technique [0002] Shale gas is an important replacement resource in the world, and its exploration and development technology has become a research hotspot and difficulty. Brittleness is one of the important mechanical characteristics of rocks and a key parameter for the fracturing of shale gas reservoirs. According to the fracturing properties of shale gas reservoirs, favorable well locations or "sweet spot" locations can be determined. [0003] Usually, estimating rock brittleness by using brittle mineral content is the most intuitive and accurate, but it must be based on rock sample test data and well logging analysis, and local rock sample test results and single well analysis results cannot objectively reflect the brittleness distribution characteristics of surroun...

AI Technical Summary

Problems solved by technology

However, there are cumulative errors in indirect calculations, which greatly reduce the calculation accuracy of Young's modulus and Poisson's ratio, and the inversion method based on the approximate formula of the Zoeppritz equation is effective in using the large offset seismic amplitude (large angle) information and the joint inversion of P- and S-waves. There are big problems in the aspects of inversion and other aspects, which seriously restrict the improvement of pre-stack inversion accuracy.

Therefore, the above method of obtaining Young's modulus and Poisson's ratio cannot meet the requirements of fine characterization of rock brittleness in actual reservoirs in terms of calculation accuracy.

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