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Hudson Bay, New York, USA
Electronic Resistivity Tomography (ERT) data was required by the client to ensure that their cables were installed safely. They commissioned Sulmara to collect, process and profile ERT data over multiple challenging shallow water sites in the Hudson Bay, New York, so they could correlate with their seismic reflection and refraction data.
The Sulmara marine ERT system is a continuous profiling system that is towed and consists of a single cable with two source electrodes and 8 measuring/sampling electrodes. With the vessel was moving forward at about 0.5 - 1 knot and a measurement performed approximately every 3 seconds for a duration of 800 ms (0.8 sec).
The results give a new reading approximately every 1 meter of travel. This dense sampling allowed for some data clean-up and meaningful information for the client’s engineers.
The damaged caused completely ruined the cable and another one (the only other one in the US) was sourced and shipped out the next day. The new cable was not a direct replacement, but it was able to get the job done and we were able to integrate both data sets without issue.
Conditions in Reynolds Channel were very challenging with strong tidal currents, little manoeuvrability, and winter temperatures. Cold temperatures would cause the topside controller to freeze up and miss measurements. After each profile, the data was checked and if measurements were missed then the profile would be rerun. We also made physical adjustments to the setup which mitigated the dropped measurements due to the cold temperatures.
The client was able to safely plot the route to shore of its windfarm cables ensuring the HDD drill avoided all major obstacles.
