Orientation of a 3-C VSP Dataset Acquired by Integrated Geophone Sensor and MEMS Inclinometer Devices

This paper seeks to gauge the performance of a new commercial downhole VSP tool electronics module, which has been recently implemented with a 3C solid state inclinometer system called a High Side Indicator (HSI). The HSI measures the direction of the pull of gravity and calculates the angles of roll and vertical inclination in each shuttle of the borehole seismic toolstring. By so doing, the VSP tool manufacturer expects to (a) replace the previous gimbal settings systems, which proved voluminous, fragile, inaccurate at low inclination, and mechanically difficult to maintain through the lifetime of a VSP tool, and (b) encourage full 3C processing of all downhole datasets, even those acquired within rig source VSP survey geometries. The first objective of this test was to check that the VSP hardware and acquisition software worked as expected, and secondly to define a minimal field QC procedure which includes at least the roll angle rotation and associated 3C VSP displays. From this the field engineer and the client supervisor can be reassured as soon as possible about the overall VSP data quality and usability for advanced full 3C VSP processing by the geophysicists and interpreters.