Analysis of Converted-Wave Splitting in Volcanic Rocks - A Case Study from Northeast China

Converted shear-wave splitting provides a practical means for evaluating azimuthal anisotropy in hydrocarbon reservoirs that may give some insights into the internal architecture of the reservoirs. In this paper, we evaluate converted-wave seismic data acquired over volcanic gas reservoirs. The converted-wave data reveals a significant amount of shear-wave splitting over the volcanic formation, and we develop a technique to extract the shear-wave polarization and time delay from the data. The technique is particularly designed for evaluating converted-wave splitting for 2D or 3D data with a narrow-azimuth distribution. We adopt a rotation-scanning procedure that maximizes the separation of the fast and slow split shear-waves. It is interesting that the amount of splitting determined from the data can be correlated to the known gas reservoirs, revealing a potential to use shear-wave splitting to delineate gas reservoirs in volcanic rocks.