Pipeline Construction to Osprey Platform Cook Inlet, Alaska

This project took place in a very rough area of Cook Inlet that was exposed to weather from the north and south. The project began before the sea ice had left and lasted several months. Safe operation took considerable thought and planning due to weather, ice, large tides, multiple vessels working the project, anchor lines in the area, and shallow water on the shore end. We were able to provide all of the support services and data without injury, or equipment failure.

The preconstruction and as-built surveys were performed with a sidescan sonar and shallow-water multibeam sonar system. Our Edgetech DF1000 dual-frequency digital sidescan sonar was used along with Triton Isis data collection software for the sidescan sonar survey. Our Reson 8124 and a leased Reson 8125 shallow-water multibeam was interfaced to Reson 6042 data collection software for the bathymetry.

Our staff collected, processed and provided data as both plan view drawings and plan-and-profile drawings with route depth information shown in profile. Shaded imagery generated from the shallow-water multibeam data was used to detect and avoid rocks and other obstacles as well as plan for stabilization work. This imagery pointed out several undetected problems, including severe scour around the platform.

We positioned the lay barge and two tug boats during the pipe lay and installed and operated multibeam and sidescan sonars during the pull into the platform leg for each pipeline. While remaining on one of the vessels, our surveyors were able to provide control for the other vessels through the use of a wireless Ethernet network, special hardware and software.

Sector-scanning sonar was used to track the location of the pipeline during the critical pull into the platform leg.

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