Use of vibrator performance data to improve near-surface velocity determination

Reliable estimation of near-surface P-wave velocity is one of the key problems in land seismic exploration. Uphole surveys are usually used to acquire near-surface velocity information. However, in the presence of rapidly varying near-surface geology, such estimation is inherently uncertain due to the sparse uphole sampling grid.; A principal goal of this study is to determine a relationship between the densely sampled vibrator performance control data, obtained in the course of normal seismic data acquisition, and uphole P-wave velocity so that the two data sets can be integrated using geostatistical techniques to provide improved near surface velocity models.; A theoretical model was derived relating near-surface P-wave velocity to vibrator control system estimates of ground stiffness and viscosity. Estimated velocity from these vibrator measurements exhibited good statistical correlation over a large 3D seismic survey area with uphole velocities down to a 50-meter depth.; Two 3D near-surface velocity models were constructed using uphole data alone as well as combined with vibrator information, both of which were used to calculate statics. The seismic imaging results obtained using these statics were found to be better than using uphole data alone. On the basis of these results, we concluded that the integrated model resolved statics better than models that individually utilized uphole data through geostatistical and conventional computation techniques.