Improving the Low-frequency Content of Borehole Seismic Data Acquired Using an Air-gun Source

Abstract

Abstract: The targets for offshore borehole seismic (BHS) surveys are becoming more challenging because they are deeper and overlain by more complex subsurface formations. Coupled with this is a move to more advanced acquisition methodologies such as 3D vertical seismic profile (VSP) surveys, as well as a desire for more powerful seismic sources that are also capable of generating wider-bandwidth data, in particular with increased low-frequency content. Low frequencies have a variety of benefits including overcoming the high-frequency attenuating effects of the Earth, improving vertical resolution, enhancing inversion results, and improving velocity analysis. A new BHS air-gun source array design has been introduced that significantly improves the low-frequency signal level but is a compact size that enhances the safety of deployment and towing.