Tomostatics applications for basalt-outcrop land and OBC multi-component surveys

Abstract

Tomostatics have been recently applied to two types of data sets. The first is from the Middle East region where the near surface layer is exhibiting high-velocity basalt outcrops and the second is a multi-component (4C) OBC data set containing low-velocity gas clouds. Near-surface velocities estimated from turning-ray tomography provide useful information for geologic interpretation and structural imaging. Tomostatics have shown advantages over traditional refraction statics in regions where (1) no refractors can be easily identified, and (2) high velocity materials (e.g. basalt) are overlaid on top of the low velocity sediments immediately below the topography. P-wave velocities estimated from turning-ray tomography can be used to calculate the traveltime contours. Correlating P-wave and converted-wave traveltimes would allow us to estimate Vp/Vs ratios, leading to a practical approach for converted-wave long-wavelength statics solution.