Abstract：We propose in this paper a polynomial fitting centroid frequency shift to estimate nearsurface Q. With newly designed single-well uphole layout, we estimate centroid frequency and relation between variance and offset by a model trial, which meet the cubic polynomials. The centroid frequency shift method based on polynomial fitting is used to estimate nearsurface equivalent Q value. The estimation is very close to the equivalent Q value of the model. The proposed approach is applied to real uphole data of the area C. The nearsurface equivalent Q value is estimated, and the parameters a and b of v-Q empirical formula applicable to the work area are fitted. Compensation of nearsurface absorption to real seismic data with nearsurface equivalent Q improves much seismic data resolution.
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