hti medium avaz quantitative inversion method and system

Abstract

A method and system for quantitative inversion of AVAZ in HTI media are disclosed. The method may include: step 1: establishing an initial model including N time samples of seismic traces based on the anisotropy term and azimuth; step 2: obtaining observation data according to seismic record differences corresponding to different incident angles and different azimuths; Step 3: According to the azimuth reflection coefficient difference matrix and the seismic wavelet, obtain the seismic synthetic record, and then obtain the seismic synthetic data; Step 4: According to the observation data and seismic synthetic data, establish the inversion objective function F(m+Δm) and perform Inversion; Step 5: When F(m+Δm) does not meet the set accuracy requirements, modify m to m+Δm, and repeat step 3-5; when the set accuracy requirements are met, stop the iteration and use the iterative model as the inverse Output the result of the performance. The invention utilizes the difference in amplitude and orientation to quantitatively invert the anisotropy item and the azimuth angle for the differences in the longitudinal wave reflection coefficients in different observation directions, and improve the fracture prediction accuracy through the quantitative inversion.

Description

technical field [0001] The present invention relates to the technical field of oil and gas geophysics, and more specifically, to a method and system for quantitative inversion of HTI medium AVAZ. Background technique [0002] As a channel or storage space for oil and gas migration, fractures are one of the important parameters for reservoir sweet spot evaluation. The existence of fractures leads to the anisotropy of the underground medium, and due to the compaction of the overlying load, vertical or high-angle fractures are mainly distributed in the reservoir, which can be equivalent to HTI (a transversely isotropic medium with horizontal axis of symmetry) medium . Seismic identification techniques are playing an increasing role in fracture prediction. In the early days, people described fractures based on the shear wave splitting characteristics caused by fractures; however, the cost of multi-wave and multi-component seismic exploration is high and the processing process ...

AI Technical Summary

Problems solved by technology

In the early days, people described fractures based on the shear wave splitting characteristics caused by fractures; however, the cost of multi-wave and multi-component seismic exploration is high and the processing process is complicated. Research, in which the accuracy of fracture prediction using the longitudinal wave azimuth reflection amplitude information, namely AVAZ (Amplitude variation with incident angle and azimuth) is the highest

According to the survey, there are relatively few studies on quantitative inversion based on the linear approximation formula of reflection coefficient. The paper "AVOA Inversion of Fracture Parameters Based on Equivalent Medium Model" published by Xue Jiao in 2016 can directly analyze the seismic time series at any point. Quantitative prediction methods directly quantitatively invert the approximate formula of reflection coefficient. However, this method involves many parameters, and the existence of parameters such as velocity, density, or impedance may easily cause errors in the prediction results of anisotropy items.

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