oa Getting a better control of IP acquisitions with GDD’s new IP Post-Processing software

There was a time when an entire day of Resistivity / Induced Polarization (IP) acquisition would have to be re-surveyed because wrong survey parameters had been set, timing errors had occurred, wind or external noise had prevented acceptable repeatability of readings, etc. This frustrating and costly outcome was due to the absence of full wave data available for the geophysicist to process. For both ground and borehole EM and IP surveys, the lack of data for post-processing and post-processing capabilities remained for a long time, until more recently some manufacturers started offering access to time series along with software to visualise and process the data.

Instrumentation GDD, a Canadian manufacturer of geophysical instruments since 1976, is one of them. The GDD IP receivers’ full wave data were accessible since 2009 but users can now use the IP post-processing software. This paper will include many examples of real data collected in different part of the world for which it has been possible to: validate the nature of external noise to adjust acquisition parameters and fix final survey results, correct synchronization offset between the transmitter and the receiver, manually discard noisy half-cycles to recover data in specific cases for which the receiver algorithm did not yield satisfactory results, modify the secondary voltage (Vs) decay windows scheme in order to fine-tune chargeability responses in specific geological environments, and more.