Seismic attenuation measurements from multicomponent vertical seismic profile data

Carlos A. Montaña

Vertical seismic profile (VSP) data provide a means to estimate the seismic wavelet at dif- ferent receiver depths. The downgoing wavefield has always been the key to measure atten- uation (Q) and enables us to correct for the effects of seismic attenuation on seismic data. We demonstrate that we can also use the upgoing wavefield to estimate Q, using reflections and mode-converted waves. In this work, Q is estimated from synthetic VSP downgoing and upgoing wavefields by using the spectral matching method. We also estimated Q, using the spectral matching method, from VSP data collected in a 500 m deep well in a heavy oil field and a 2000 m deep well in a shale gas play in Western Canada. For the first case, we obtained values of QP of approximately 50 and QS of 20 for the strata intersected by the well. For the second case, we obtained values of QP of approximately 50 and QS of 30. In the case of QS estimations, our results indicate that using the upgoing converted wavefield provides good estimations when downgoing S-wave are not available in the data.