Abstract:Direct downgoing wave in VSP data has strong energy and highsignal-noise ratio,which favours the calculation of absorption para-meters.However,the existing methods for calculating absorption para-meters can not effectively remove the influence of upgoing wave anddowngoing short-path multiple,so that the absorption parameters cal-culated using downgoing wave are not accurate enough,Comparativelyspeaking,"the amplitude spectrum ratio method" is used quite uni-versally and not influenced by the variaton of source energy.The am-plitude spectrum ratio method is improved here.By using the reflec-tion coefficients which were obtained from sonic and density loggingdata,the amplitudes of direct downgoing waves in nonelastic absorp-tion case are corrected so as to remove both the interference of up-going waves and the influence of short-path multiples.Then quali-ty factor is calculated using the amplitude spectrum ratio method,Theimproved method is called post-correction spectrum ratio method,Qu-ite accurate absorption parameters in medium and their improved spavial resolution can be obtained using VSP data as well as qualitysonic and. density logging data.The trial of SVSP data proved thismethod feasible.
王彦春, 董敏煜. 用VSP资料求取吸收参数方法的研究[J]. 石油地球物理勘探, 1990, 25(6): 662-675.
Wang Yanchun, Dong Minyu. A study of the methods for deriv-ing absorption parameters from VSh data. OGP, 1990, 25(6): 662-675.