Subcon Australia has successfully completed an offshore grouting campaign, in collaboration with Pipeline Drillers Group (PDG), Bhagwan Marine on the stabilisation of an HDD pipeline. The pipeline, located in the East Gippsland Basin of the Bass Strait, has been installed as part of a new gas field development project.

Due to high currents and extreme wave loading contributing to pipeline instability, the 12” pipeline required specialist structural support and tie downs.  These requirements demanded heavy additional weights, an installation challenge for remote locations with smaller vessels that typically have limited lift capacity.

To facilitate the use by our client of an economical marine spread, Subcon’s innovative solution was to install inflatable heavy density pipeline supports and ballast matts.  The scope consisted of the fabrication, supply and grouting of custom stabilisation formworks in 20m water depth, onboard Bhagwan’s “Dryden” dive support vessel. Subcon was able to deliver value to the client by providing a proprietary 3.5SG Heavy Density Grout, removing the need for a larger vessel.  The use of HD grout instead of Portland cement reduced the volume of grout required by almost 50% compared to conventional marine grouting methods.  This meant the scope could be delivered in one trip providing further savings on vessel spread costs.  The experienced crew utilising Subcon SPM5000 grouting equipment were able to complete all grout works in 4 days, despite difficult weather conditions restricting daily grouting times to as little as 3 hours.

PDG project manager, Colin Harris, said, “Subcon’s crew were extremely hard working, diligently safe and thorough in their execution.  The works were completed quickly and safely and the vessel was left in meticulously clean condition”.

This marks the second application of Subcon HD Grout, the first being deployed by Chevron at their Wheatstone platform, in conjunction with DOF for stabilisation of the umbilicals and flowlines around the Wheatstone Platform.

Subcon Heavy Density Grout reduces vessel crane capacity, schedule and deck space requirement

Offshore 2Te multi-use bulk bags are used to load Subcon’s Super Pan Mixer