VSP Tool Orientation Using Magnetometer and Inclinometer Sensors

Onshore wireline borehole seismic in rough, mountainous foothill terrains is very often restricted to rig source VSP and Offset-VSP using a single fix surface source, one run per source position, for economic reasons. This technique also applies to common offshore rig-source VSP surveys.

Complex subsurface tectonic complicates surface seismic imaging and borehole seismic imaging is equally difficult. Solving structural feature in the borehole vicinity can benefit from three component (3C) VSP processing techniques, but it requires orientating the 3C data at pre-processing stage.

The orientation of the three-component VSP signals recorded in a near-vertical well section, mostly cased, was successfully obtained by combining in the field a magnetometer-inclinometer orientation tool, namely the common GPIT * general purpose inclination tool, to a single-level VSP tool with fixed setting of three-component seismic sensors, available at the time.

Future field acquisition of rig-source and fix offset source VSP surveys can benefit from combining a magnetometer & inclinometer sensors to at least one of the recording tool of the multilevel VSP tools routinely used nowadays.