Geoquip Marine has successfully completed a highly challenging offshore windfarm geotechnical investigation in harsh environmental conditions off the coast of Japan.
Geoquip and strategic partner Fukada operated the highly capable Poseidon 1 for the project for Influx Offshore Wind Power HD. Poseidon 1 is a DP2 vessel with a twin tower derrick permanently installed over a central moonpool.
The presence of rock below mudline made standard push sampling and CPT testing techniques impractical to complete the boreholes. As a result, Geoquip Marine chose to utilise a wireline core barrel to recover rock cores and progress boreholes. Geoquip was able to perform coring in rock utilising the standard API drill string because the Geoquip system enables the use of wireline core barrels without the need to recover the drill string.
“The fact that sampling, CPT testing and coring was able to be completed with a single drill string when changing mode from sampling and CPT testing to coring meant that the process was completed very rapidly and highly efficiently,” explained Project Manager Torran Purchase.
“Utilising the wireline core barrel in these circumstances provided us with really excellent recoveries – whilst allowing us to change back to sampling and CPT testing if necessary. Ultimately it provided excellent quality rock cores in very difficult conditions with less than one per cent downtime.
“Given the challenging conditions experienced throughout the duration of the work, the time saved by not having to recover the drill string to perform coring, improved safety by reducing the risk exposure of the drill crew whilst allowing operations to be completed in shorter weather windows, which contributed to the contract being completed with no safety concerns whatsoever,” he concluded.