Global Geophysical Services Inc. of Houston has invested in an Ocean Bottom Cable (OBC) acoustic positioning system from Sonardyne International Ltd (Stand No. 926 OI 2008). The system will be used to support the company's expanding shallow water seismic survey activities and will employ a large network of low cost acoustic transponders to accurately position hydrophone ground stations in water depths up to 500 metres.
The order also includes Radio-Frequency Identification (RFID) tags for each of the transponders so they can be accurately logged as the hydrophone cables are deployed from the ship. Deliveries of the equipment have already been completed in readiness for Global Geophysical beginning a major survey offshore India.
Global Geophysical will use its new acoustic positioning system in conjunction with Sonardyne's ‘HydroPos' seismic control software. This monitors time tags and logs raw data from the vessel's acoustic transceiver and its surface navigation systems such as GPS and gyro. This will make it possible for Global Geophysical's surveyors to obtain real-time positions of the transponders quickly and accurately, thus enabling very efficient surveys. Raw acoustic data can also be passed to an external navigation system so that absolute positions for the hydrophones can be obtained.