The field development consists of two offshore production wells, completed subsea with a 34 km subsea pipeline to shore, a 2 km horizontally direction drilled (HDD) shore crossing and a 12 km onshore pipeline to transport gas to the Iona gas facility near Port Campbell.

Construction and installation of the 12 km onshore pipeline, consisting of a 12 inch diameter pipe, three 2 inch diameter pipes and an optic fibre cable, began in January 2005 and was completed by late March. Installation of the main line valves will follow in August 2005 after the shore crossing is completed.

Pre construction

Peter Thomas, Onshore Construction Manager for Casino, said that the construction of the pipeline proved to be one of the quickest projects of its type to be executed, thanks in part to a rapid approvals process. Enesar, who have assisted Santos with their Department of Primary Industries (DPI) approvals before were again on hand and the approvals process, which commenced in late 2003 was completed by October 2004.

Landowner issues were also handled quickly and effectively, with all landowners signing easement agreements and no compulsory acquisitions required. This was largely due to the excellent job done by Santos’ land negotiator, Ian Gordon. When developing the pipeline route, existing boundaries and easements were followed as closely as possible in order to minimise any landowner issues that could arise, resulting in a pipeline route that Peter describes as one of the best he has been involved with.

Lessons learnt from involvement in and observation of previous projects, both in the area and elsewhere, proved beneficial in the timely execution of this project. Coming into this project, Peter and his management team knew that one of their critical decisions would be to subdivide the project into work scopes within the capability of regional and local contractors and the selection of those contractors.

Mitigation and management measures were implemented to handle a range of issues, with a focus on minimising vegetation clearance, preservation of top soil, erosion and sediment control, dust control, traffic management and the construction of the pipeline crossing of Campbells Creek. Negotiations regarding Native Title were also successful following meetings with potential claimants.

As well, there were several other environmental issues that required attention. Flora and fauna native to the area needed to be protected, with particular attention paid to the Southern Brown Bandicoot, which is listed as endangered under the Commonwealth EPBC Act. To minimise any stress that may have been caused by accidental entry into the pipeline trench, exit ramps were put in place at the end of each day.

The project management team also had to develop a strategy for handling the fungus Phytophthora Cinnamomi. This fungus attacks the roots of native vegetation causing die back, so the team developed a procedure to prevent the transmission of the fungus to remnant vegetation during construction. The procedure included the use of crushed limestone in which the fungus does not survive. Any equipment which came into contact with the fungus was sprayed with the disinfectant, Phytoclean.

Construction

Aside from the environmental specifications set out for the project, several construction specifications also had to be adhered to. Santos was advised that no more than 500 m of the trench could be open at any one time, a measure designed to reduce the weather risk. Trenching works were then carried out at a similar speed to that which the four pipes and optic fibre cable could be installed, laying side by side in the trench.

Corrosion Control Engineering provided an automatically controlled cathodic protection system consisting of a potential controlled rectifier and an anode groundbed.

The mainline and the three 2 inch MEG lines are provided with independent cable connections which are bonded within each test point installation. The independent cable connections enable electrical isolation to be achieved if required.

In three locations along the route, the pipeline construction required polyethelene casings for bored road and existing pipeline crossings to facilitate installation of the three 2 inch MEG pipelines. In each case, the pipelines within the casings were backfilled with a bentonite mix and provided with additional protection. Permanent reference electrodes were provided to enable monitoring of cathodic protection levels within the casings.

Temporary protection of the pipelines during construction was provided via magnesium anodes installed as construction proceeded.

Main contractor Mitchell Australasia commenced on-site construction at Port Campbell on January 4 2005, with work on service locations, fencing, site office set-up and plant mobilisation all having taken place prior to Christmas, 2004.

Initial activity was focused on the ‘Clear and Grade’, with graders and dozers stripping and windrowing the topsoil from the pipeline Right of Way for the entire length. An impressive 1,000 plus metres was cleared per day. Santos had specified that a total depth of 150 mm of top soil and vegetation were to be removed and preserved along the Right of Way in order to maintain farming land fertility along the pipeline route following rehabilitation.

Once the clearing was taken care of the stringing crew began their work, laying pipes direct from the semi trailers loaded with Kembla Grange pipe. The Vacuum Lift made easy work of it and 2000 sawdust bags and 200 polystyrene blocks were used to support the pipes on the Right of Way.

Welding of the pipe followed, and Project Superintendent Tony Tschappeller said that it was great to see guys working in all ranges of weather without a thought of stopping. The welding teams worked in the sweltering heat, fully clad in protective gear, upside down under pipes all day long, and according to Tony, they were long days too.

Brad Marsh’s coating team were next on site and these guys have been described as the key to the whole operation, due to the fact that if the coating got behind, everything got behind. This involved sandblasting the joints, heating the joints, applying a liquid coating with a paint roller then testing the dried product for adequate thickness. When the weather turned against the team, whether it was cold with misty rain or hot with northerly winds blowing up dust, the guys persevered and, with the help of purpose built canopies, got the job done, lifting production to the highest levels whenever they could.

Denso Australia supplied Canusa HBE95 brush grade for the 12 inch FBE coated pipeline and S43/R23 Butyl Tape system for the 2 inch polyethylene coated lines. Training was also provided by Nasa Chaabani from Denso. While predominantly used on the mainline for this job, HBE is gaining respect in the HDD industry as a joint coating for Naprock or FBE coated pipe.

Trenching was carried out with the “Proud Mary” Cleveland Trencher, which opened up the 1350 mm wide trench 1.5 metres deep with great ease. Following this, pipelay commenced, which was no simple task given that four lots of pipes measuring a total of 48 km plus optic fibre cabling had to be installed. Once pipelaying was finished, backfill proceeded immediately.

The clean up process began once enough pipe was in the ground to get a clear run. The process involved shifting all the clays back into place and compacting, before spreading the windrowed topsoil back across the easement to be ready for re-grassing.

One of the main challenges faced during the project was the tie-ins which were needed at every bend and every road crossing bore, but this task was well executed thanks to an experienced team. At the ‘tie-ins’, pipes had to be welded together down in the hole and one of the major difficulties here was trying to separate the four pipes enough to get the welding rod around, then trying to get them back together again at the required spacing. BTB Australia took care of the bores without difficulty, one of which was over 90 m long.

Several pipeline crossings proved to be among the more delicate aspects of the project. In all, five existing gas lines were crossed – the Minerva pipeline which had three pipes, the SEA Gas pipeline, a TRUenergy line and a GasNet line, all of which were crossed twice and the SEAMER and Skull Creek lines, both of which were crossed once. Crossing the Minerva line was the most difficult of all these pipelines. BHP Billiton was concerned that if the pipeline was trenched under, damage to the delicate umbilical could be caused. BTB directionally drilled the Minerva crossing, while for the other crossings the open cut method was used.

Several road and creek crossings also had to be negotiated along the pipeline route, with a combination of road bores and open cut crossings performed. The Campbells Creek crossing, for example, was an open cut crossing conducted under strict environmental controls. All in all there were three HDD crossings, two open cut road crossings and six gas line crossings.

Inductabend supplied approximately 18 twelve inch and 54 two inch hot induction bends and epoxy coating. The pipe was free issued by the Mitchell Group and included twelve inch X70 and X65 pipe and some smaller two inch pipe. Bend angles varied from 30 through to 90 degrees.

Post construction

Since installation of the pipeline wrapped up several months ago, reinstatement of the right-of-way has been completed and revegetation of areas cleared of native vegetation at the roadsides will be undertaken in the spring of 2005 in accordance with a rehabilitation plan prepared consistent with Victoria’s Net Gain policy.

David Emslie, the Casino Project Manager and Peter said they were both happy with the support received from the contractors working on the job noting that there was an alignment of objectives for contractor and proponent. Peter said that managing this project was almost like working on an alliance project, with all involved working towards the same goals – completion on time and on budget while maintaining a good relationship with affected property owners.

Main contractor Mitchell Australasia echoed these sentiments, describing Santos as a wonderful team to work with. Ross Bennett from Mitchell said, “A commitment to all working well together set this project apart – there was nothing that couldn’t be overcome or sorted out. Help was only a phone call away.”

The shared interests of Santos and the contractors meant the potential problems that can arise when a small job is set an aggressive time frame for completion were negated. While issues on projects with short time frames arise constantly, the project management team was able to make these decisions without halting construction.

Site restoration

David said that Santos was pleased with the performance of Mitchell in terms of planning, construction and site restoration, with both safety and environmental issues handled well. Environmental aspects of the project were of paramount importance to Santos, and as David says, “The industry has a responsibility to minimise environmental impacts.”

Local landowners expressed their satisfaction with the finished site at a barbecue Santos held for residents when the project was completed. David said the satisfaction of nearby residents was a critical factor for the project because it was important to maintain a good relationship with local landowners not just for Santos, but for the industry in general, given the number of projects currently being developed in the area.

Looking ahead

Current developments at the Casino Gas Project are focused on the drilling of two development wells which are due for completion early in July, and preparations ahead of the installation of the offshore pipeline which is scheduled to commence in the last quarter of 2005.

Offshore construction involves the installation of the subsea pipeline and umbilical connecting to the shore crossing site. It is expected that installation will take approximately eight weeks using the Seaway Falcon pipe lay vessel and a diving support vessel.