Navigation and Navigation Data Processing

Experience relevant to the position of Geophysicist         Return to Cover Letter

For Western Geophysical in Venezuela,  I worked with some early GPS data that we used to calibrate the survey data on seismic projects around lake Maracaibo.  The receivers were 80-pound Wild/Magnavox “suitcases” that accumulated many satellite passes (the GPS network was far from complete) over hours or days. The data were recorded and post-processed on IBM PC’s.

I did data processing and QC for a transition zone (3D) project along the Eastern shore of Lake Maracaibo.  I trained aboard the Western Atlantic to process  radio navigation data from the boats deploying the hydrophones recorded by a Sercel 368 system that had been “hardened” for shallow marine recording.   The source boat navigation data also had to be processed and QC’ed.  I trained the navigators for the receiver deploying “nav boats” and I was called upon to take over as night-shift navigator of the source boat during acquisition.

This was Universal Transverse Mercator (UTM) coordinates, in the appropriate zones, but I also worked State Plane Coordinates in Texas, New Mexico and Louisiana.

Later, I was stationed aboard the Western Atlantic, making 2D brute stacks of the 3D marine data as it was acquired from Lake Maracaibo..  I also did QC and processing of positioning data from the navigation boats that deployed the telemetry buoys and hydrophones.  The binning coverage was also my responsibility with a very early real-time binning system which had to be edited and recalculated daily.

At Petroleum Geo Services (PGS,) there was a methodology that analyzed binned coverage based on geophysical parameters. Pre-stack time migration on modeled data was used to establish a tolerance level for coverage gaps permitable for each of four offset ranges.  Navigation data were forwarded to the office by satellite in order to be binned and analyzed as to whether infill would be appropriate and results delivered to the clients and the vessel overnight.

There was a series of surveys over a permanent installation of fiber-optic cables and sensor installed around a platform off Brazil.  Mine was the survey design and I tracked the coverage in the Houston office as the source point navigation data were sent in by satellite.  Updated coverage maps by eight offset ranges were produced and presented on a bi-weekly basis.

While all the previous was going on, we also did airgun source modeling for every array configuration on every job PGS’s Marine Source Modeling Utility (MASOMO) is an industry standard package that is solidly backed up by field research.  In the last years at PGS, I was the go-to authority on source modeling and instructed on the use of MASOMO at PGS and places like CGG and ExxonMobil.  While this is not directly related to navigation, it is highly relevant to marine operations.

I hope that this document has made clear my considerable experience in navigation and navigation data processing

Steve Campbell                   Return to Cover Letter

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