Estimation of quality factor Q from pre-stack CMP records using EPIFVO analysis

We present a method for estimating quality factor Q from pre-stack CMP records. First employing a function with four undetermined parameters to approximate the source wavelet, the relation between the instantaneous frequency (IF) at the envelope peaks of seismic wavelets (EPIF) and offsets is derived based on the theory of one-way wave propagation in a 1D viscoelastic medium; then we calculate the EPIF of every non-zero offset trace of every event to extrapolate the EPIF of zero offset trace of every event based on the relation; finally Q is estimated by combining WEPIF with the reflectivities information. Applied to pre-stack CMP models and field record, it produces a Q-curve which indicates that the extent of absorption corresponds well to the gas saturation of reservoirs.