PP And PS Waves Joint AVO Inversion And Fluid Prediction

For seismic exploration, the multicomponent seismic as the new technology becomes theorient of the exploration. But how to use the rich information of amplitude of multicomponentseismic waves is the key problem in hydrocarbon detection. So in this thesis, we put researchon the study of PP and PS waves joint AVO inversion and fluid prediction.As the other methods of seismic inversion, joint AVO inversion is not perfect. Theresults of joint AVO inversion are ambiguious, and joint AVO inversion is not stable.Meanwhile, the parameters inverted by joint AVO inversion are not sensitive to fluid. So inthis thesis, we input PP and PS angle gathers into the two-term AVO lineared inversion.In order to improve the inversion’s results’ sensitivity to hydrocarbon, we test thesensitivity of some elastic parameters. Then we choose the fluid factor of Russell which issensitive to fluid and has clear physical meaning as the inversion aim.In order to handle the problem of unstability and ambigiousness of the joint AVOinversion, we derive two-term approximations in two ways in this thesis. First of all, we usethe converted wave reflection coefficients to replace the density term in the AVOapproximations. Then we get a approximation in terms of fluid-term(f) and shear module.Secondly, based on the Russell(2011)’s equations, we reexpressed the AVO equations interms of fluid-property(f).Based on these equations, we build up target functions and submit these equations intojoint AVO inversion. According to the numerical data of layer model, log model andMarmousi2model, we invert the parameters using joint AVO inversion. We test the resultsaccuracy and sensitivity to hydrocarbons. The final results show that both of the two methodsare using two-term inversion, and the joint AVO inversion is more stable and unambiguousthan PP inversion only. But the second method is better because of its accuracy and stability.Meanwhile, the second method can handle the noisy data well, while the first one can not.The practice proves that our methods in this thesis can improve the accuracy of theinversion and the stability. What is more, our methods can be used in hydrocarbon indication.