Orientation of 3 Component Rig-Source VSPs

About 75% of commercial borehole seismic operations are zero-offset VSPs, or “Rig-VSPs”. They are recorded before total completion in low deviated holes, with a deep open hole interval and a single casing, then multiple casing depth intervals above. Three components of geophones are recorded, with excellent mechanical tool coupling to the borehole wall, but usually the VSP tool cannot be oriented into geographical coordinates. Therefore only the Z-axis component is processed, or a near vertical component computed from the 3 recorded components, resulting in a reduction of the geological information derived from rig-VSPs. APS and IFPEN propose to implement current and future generations of VSP tools with cost effective fluxgates and inclinometers to improve the present situation.