Joint AVO analysis of PP and PS seismic data

Yong Xu and John C. Bancroft

This paper makes efforts to explore joint-analyzing the amplitude versus offset phenomena in the PP and PS data with expectation to reduce the ambiguity of AVO analysis by utilizing the redundancy of μlti-component AVO measurements. The convenient approximations of P-P and P-S reflection coefficient are obtained, which link the seismic data with the elastic parameters that are sensitive to the hydrocarbon existing in the rock. A great deal of model and real data is used to test the methods.

In this paper, we derive the approximation of PS reflection coefficient from Zoeppritz equation, correct Aki and Richards's approximation, and derive some equations of PS reflection coefficient possibly easy to be used in PS AVO analysis.

We study the laboratory and well logging results, and show the difference between bulk modulus (λ) and rigidity or shear modulus (μ) is influenced by fluid-fill more purely, and it is a sensitive and quantitative indicator of gas existing.

P-P and P-S reflection coefficient equations are expressed with the elastic parameters (λ and μ, or κ and μ) in the paper. And it is shown by the well log that this kind of expression magnify the changes embedded in the Vp and is advantageous to extract the anomaly caused by fluid-fill.

The method to extract the zero offset section or approximate normal incidencesection is present in the paper. The method in this paper is based on the PP reflection coefficient with only care on constant term independent of incident angles.

Wells and 10 Hz vertical component seismic data from Blackfoot, Alberta areused to test our methods and theory. We amplitude-preserved process vertical component data, and extract the elastic parameters and zero offset. We are workingon the radial component data set and hope the elastic parameter extraction from radial component may support the extraction from vertical component data set.

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