Case Study: Cable Route Survey

Gardline Geosciences mobilized a sea-floor resistivity, CPT and launch system on board a cable-laying vessel in Denmark.  The vessel set sail for the south of France where it was joined by Gardline Geosciences' offshore survey team for commencement of operations.

Data

Throughout July and August, a burial assessment survey was conducted using data collected from the offshore operations.  This data included continuous resistivity traverses between the 10m and 1000m contours off the coast of North Africa and Southern Italy and CPT data from strategic points along the survey route.

Resistivity data was collected using Gardline Geosciences' DSR 3000 bottom towed sledge with a 7-channel streamer configured in an Inverse Schlumberger array.  Penetration depths were estimated to be in the order of ª3m with a current of up to 25 amps at 48.5 volts.

CPT data was collected using the Neptune 3000 miniature seabed frame, pushing 2cm2 piezocones to a depth of 3m with maximum tip loads of up to 25 MPa.

Deployment

All equipment was deployed using Gardline Geosciences' own launch and recovery system (LARS) which is fully containerized for ease of transport globally.

The LARS comprises a 7m A-frame with launch deck powered from a 7 tonne load sensing umbilical winch with automatic render function.  The winch has its own temperature controlled hydraulic power unit that coped well with the almost constant 30-40∞C temperatures on deck.