Prestack AVO Inversion of Exact Zoeppritz Equation Using Adaptive Edge Preserving Filter

Amplitude variation with offset (AVO) pre-stack inversion is an effective method for reservoir prediction. The traditional AVO method is based on the Zoeppritz approximate formula, which will lead to inaccurate inversion results when the difference of incident angle and formation impedance are large. In addition, it will be affected by noise and the formation boundary may be blur. To overcome these shortcomings, a new method is proposed. First, the exact Zoeppritz equation prestack inversion (EZPI) is used. Second, the L2 norm of the second order difference matrix is added to the objective function to enhance the anti-noise performance (EZL2). Finally, the adaptive edge-preserving filter (Ad-EPS) is used in every iteration (EZL2AEPS) to make the formation boundary clearer and obtain block structure. Ad-EPS scans windows automatically to find the most suitable filter window for each sampling point. Levenberg-Marquart algorithm is used to implement the inversion process. The synthetic data test shows the superiority of EZL2AEPS, which not only has excellent anti-noise ability but also can recover the formation boundary accurately. The example of the real data from a coal mine is also proposed. The parameters of the inversion need to be continuously tested. EZL2AEPS is also able to characterize thin coal seams. The boundaries of upper and lower bedrock can be distinguished, which demonstrates the proposed approach is feasible.