We completed testing on Santos’ 53 km, 10 inch diameter carbon steel pipeline to transport compressed, deydrated CO2 from the Moomba CCS facility east to injection wells at depleted reservoirs in the Marabooka and Strzelecki fields. The heavy and standard wall pipeline transports the dense-phase CO2 at pressures between 10-15 MPa.

We also completed testing of the related aboveground facilities.

Rigorous testing for the pipeline and above-ground facilities was required due to the unique design and
operation of CO2 infrastructure, including the need to maintain a supercritical flow of CO2 through the pipeline in an environment with pressures above 7,400 kPag and temperature above 31 degrees Celsius; and, thorough dehydration to avoid pipeline corrosion or the formation of CO2 hydrates across throttling valves at pipeline depressuring vents and the injection wells.

TESTING
Before testing could occur, a rigorous pre-cleaning process was required. Several cleaning runs were performed with an Enduro pig train to ensure the pipeline internal surfaces were burnished and substantially free of residual dust.

We used an Enduro bi-directional pig train and pig links, including cups, brushes, gauge plates and magnets with bypass sealing discs to allow for optimal cleaning and reduce ferrous material left behind from the construction process.

The pig train and a series of magnets were run through the pipeline until visual inspection showed the internal surfaces to be clean, bright and free from particulate rust and scale, and air exiting the pipeline ahead of the pig was clear and practically free of dust.

The pipeline was then filled using a bi-directional pig with high-wear discs before being strength and leak tested to 21,000 kPa and AS2885.5 requirements. The five aboveground facilities were leak tested in accordance with ASME B31.3.

DEWATERING
Once the pressure tests were completed and approved, we ran a desiccant dryer with a stage of cleaning and drying pigs to ensure no further water, debris or particles were pushed in front of the pigs as they exited the pipeline.

We were working to an acceptance criteria of less than 15 mm for the depth of discoloration of the foam pigs after being cut, but we managed to achieve less than 5 mm penetration on the handover acceptance pig – an incredible achievement for a 53 km pipeline.

The dew point at the end of the drying process was -20 degrees Celsius.

Following the drying process, a commissioning batch treatment was carried out to establish the pipeline corrosion inhibitor consisting of 1:1 mixture of Diesel and Corrosion inhibitor.

After the successful completion of the aboveground leak tests, the pipeline was then N2 purged with less than 5 per cent residual O2 content left in the pipeline with a blanket pressure of 350 kPag.

REMOTE LOCATION
We set up mobile wash down bays for the Enduro pigs on trailers specially designed to transport equipment in and out of the Cooper Basin. Located at either end of the pipeline during the cleaning and testing runs, the trailers were also set up with satellite communication so the team could receive up-to-date, live information on
how the pigs were running.

Our team worked 24 hours a day on split shifts to complete the work on time. To ensure everyone’s safety, we made sure that our trailers were set up with shade, air conditioning, fridges to store food and plenty of water, to deal with the extreme heat of the location.