Bennett Offshore

Going On and Off Location Assessment Services

Now it is possible to bring more certainty and safety to the Goin-On/Coming-Off Location process and reduce downtime costs accrued while waiting on weather.

The ability of any jack-up unit to deploy on a specific location (“Going-On”) and to demobilize from a location (“Coming-Off”) is highly dependent upon the environment (wind, waves & current) experienced during the Going-On/Coming-Off operation. Conducting these operations in environments which exceed design limits may cause damage and compromise the safety of the jack-up unit.

We provide a full suite of Going On and Off Location solutions, including both generic and site specific assessments carried out using coupled or decoupled methodologies.

Coupled analysis produces time-domain simulations of the touchdown event and can be used to visualize how a rig might behave in certain site specific situations, but the analysis is time consuming. The decoupled method, which we now offer, is based on energy principles and is highly suited for more generic assessments and for generation of complete sea state or motion limit curves. This has long been an industry accepted methodology as it enables fast, reliable and repeatable results. By utilizing the decoupled approach, we aim to extend the limitations of the coupled analysis to cover a wider range of potential environments.
Our analysis methodologies have been developed and enhanced by working closely with industry and academic leaders, focusing on key areas such as soil-spudcan interactions, leg-hull modeling and hydrodynamics. Key aspects of the coupled analysis methods have been studied under a joint development project with ABS. This study investigated various modeling simplifications which can be used to generate useful simulations for visualization.

Hydrodynamic properties such as damping and added mass, which are generally difficult to estimate, can be determined using computational fluid dynamics. Properly captured hydrodynamic properties are included in motion simulations which have been benchmarked with model test results and full-scale measurements, showing very good agreement.

As touchdown can occur at high velocities, soil-spudcan interactions can be quite different from those estimated by static considerations, and proper consideration of the rate effects is required. Soil-spudcan interaction behavior considering loading rate effects has been studied in collaboration with Advanced Geomechanics and the University of Western Australia. Soil models have been further validated through benchmarking with centrifuge tests carried out under the Wind Jack Joint Industry Project led by Marin and Deltares.

These services are offered by Bennett Offshore in cooperation with Bennett's affiliates in Singapore; Keppel Offshore & Marine Technology Centre and Keppel Offshore Technology Development.