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| Joint PP and PS AVO inversion based on Zoeppritz equations |
| Xiucheng Wei1, 2, Tiansheng Chen1, 2 |
1 SINOPEC Key Laboratory of Seismic Multi-Component Technique, Beijing 100083, China
2 Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China |
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Abstract Considering Zoeppritz equations, reflections of PP and PS are only the function of ratios of density and velocity. So the inversion results will be the same if the ratios are the same but values of density, velocities of Pwave and S-wave are different without strict constraint. This paper makes efforts to explore nonlinear simultaneous PP and PS inversion with expectation to reduce the ambiguity of AVO analysis by utilizing the redundancy of multi-component AVO measurements. Accurate estimation of ratio parameters depends on independence of input data. There are only two independent AVO attributes for PP reflectivity (i.e. intercept and gradient) and two for PS reflectivity (i.e. pseudo-intercept and pseudo-gradient or extreme amplitude), respectively. For individual PP and PS inversion, the values of least-squares objective function do not converge around a large neighborhood of chosen true model parameters. Fortunately for joint PP and PS inversion the values of the least-squares objective function show closed contours with single minima. Finally the power function fitting is used to provide a higher precision AVO attributes than traditional polynomial fitting. By using the four independent fitting attributes (two independent attributes for PP and PS respectively), the inversion of four ratio parameters (velocities and densities) would be estimated with less errors than that in traditional method.
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Received: 07 July 2011
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| Fund:National 973 Basic Research Developments Program of China (No. 2005CB422104), 863 National High Technique Research Development Project of China (No. 2007AA060505) and National Natural Science Foundation of China (No. 40839901) |
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Corresponding Authors:
Xiucheng Wei
E-mail: weixc.syky@sinopec.com
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