Sea Technology

APR 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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14 st / April 2017 www.sea-technology.com permanent reservoir monitoring installations, making nodes a viable candidate for semipermanent reservoir monitoring. We have developed a proprietary node capable of a five- year deployment life and a 300-day cumulative recording period that enables multiple monitor surveys before node recovery. A proprietary optical communication system has been integrated into the node so that data download can be performed in situ in a timely manner. We believe that deepwater reservoir monitoring with nodes will have commercial benefits over cable-based PRM systems by providing the same high-quality 4D seismic data at lower cost. ST data harvesting, it is anticipated that about twice that many nodes can be downloaded per day since the ROV does not have to repeatedly return to and dock with the subsea loader to take on new payload. It is also anticipated that the transit time between nodes can be significantly reduced when using an inspection-class ROV for data harvesting rather than the slower work-class ROV used in deployment/ retrieval. Also, as is always the case with nodes, since data are not available until all the source points are complete, there is a period of about a week of onboard QC, shot posi- tioning, timing analysis and data reorganization before final delivery. It is expected that the data retrieval will add about three days to the normal QC time. A future initiative may be to develop a data-harvesting capability utilizing an AUV to speed up the cycle time. Conclusion Ocean bottom nodes have delivered high-quality full azimuth 3D and 4D seismic data in deepwater. They have operated safely and effectively among surface and subsea infrastructure and simultaneous operations. OBN survey re- peatability is comparable to that observed for cable-based David Hays has worked in the geophysical services industry for more than 40 years, after receiving an M.S. degree in physics from Iowa State University. For the last 30 years, he has worked with Fairfield- Nodal, where he presently serves as vice president in the Fairfield Technology Group, conducting applied research in processing and imaging of ocean bottom seismic data for hydrocarbon exploration. Fairfield- Nodal is a privately held geophysical company, pro- viding proprietary and nonexclusive seismic data acquisition, processing and imaging services and nodal seismic recording equipment worldwide. "Deepwater reservoir monitoring with nodes will have commercial benefits over cable-based PRM systems."

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