Abstract：Quality factor is one of the important parameters of describing the attenuation characteristics of formation.Combining with the attenuation theory on seismic wave propagation in inelastic medium and referencing to various formation velocity definition,layer quality factor,ray average quality factor,three average quality factors and three RMS quality factors are defined respectively.And the differences and mutual relationship among different quality factors are discussed.Meanwhile, based on pre-stack and post-stack seismic data, some recursion algorithms used to estimate quality factor are given.Research results show that formation quality factor has the same layer distribution characteristics as formation velocity.Ray average quality factor is the most accurate parameter describing formation absorption properties when seismic wave propagates along different ray path, which can be used as an important precision evaluation standard for other quality factor.And it reveals the essence of QVO for ray average quality factor variation with offset.In usual seismic spread length range,two kinds of average quality factors, which are defined according to the assumption that wave propagates vertical level and similar average velocity definition,form the lower and approximate upper limits of the rays average quality factor.Apparent RMS quality factor has more practical application value than other two RMS quality factors given by the inverse of root mean square of the weighted-by-time average of dissipation rate square and by the root mean square of the weighted-by-time average of quality factor square.
