Sole Gas Field, Gippsland Basin

The Sole gas field is located in water depths ranging between 120m and 130m in the Gippsland Basin, 45km offshore Victoria. Credit: Cooper Energy.

The field is planned to be developed as a single, vertical subsea well with pipelines and umbilicals connecting to the Orbost gas plant. Credit: Cooper Energy.

The field is estimated to contain 2C contingent resources of 211PJ. Credit: Cooper Energy.

The Sole gas field is located in water depths ranging between 120m and 130m in the Gippsland Basin, 45km offshore Victoria, Australia. TThe field lies 65km away from the onshore Orbost gas plant and 35km from the Basker-Manta-Gummy (BMG) fields, which are held by Cooper Energy.

Lying in the Vic/RL3 permit area, the field will be jointly developed by Santos and Cooper Energy, while Santos will be the operator. Cooper Energy acquired a 50% stake in the field and the Orbost gas plant in 2014, for $27.5m, and will fund the initial $50m project cost.

The field is currently in the front-end engineering and design (FEED) phase, which is expected to be completed by early 2016 and will be followed by the final investment decision (FID). First gas is expected in late 2018.

Sole field geology and reserves

Lying in the east Gippsland Basin, the Sole gas field is a four-way anticline structure with the Kingfish formation of the Latrobe group being its gas-bearing reservoir.

Assessment of the field revealed 2C contingent gas resources of 211 petajoule (PJ), shared equally between the two development partners. The maximum gas column height is 71.5m and the average porosity is more than 30%.

The gas produced will be processed to remove hydrogen sulphide. The condensate production is estimated to be 40 barrels a day (bpd).

Sole gas field development details

An assessment of the field’s resources was carried out by Santos that was compiled in the preliminary field development plan in 2013 and further updated in May 2015 as part of the pre-FEED process.

Cooper Energy conducted a review to validate the findings related to the field’s resource estimate by interpreting the 2D seismic data and petrophysical analysis of the wells. Another review was conducted of the field’s hydrocarbon analysis and Santos’ interpretation of the fluid properties.

Independent reviews by Cooper Energy were also carried out regarding the field’s development plan and reservoir estimate.

The field is planned to be developed as a single, vertical subsea well with pipelines and umbilicals to Orbost gas processing plant. An estimated 1PJ of sales gas will be yielded through the development scheme.

Gas sales agreement

Cooper Energy has entered a heads-of-agreement with O-I Australia for sale of gas produced at the Sole gas field. Cooper Energy’s share of the gas will be sold to O-I Australia at the rate of 1PJ a year for the lesser of eight years, or the life of the field, whereas the remaining will be sustained by Santos.

The agreement accounts for 8% of Cooper Energy’s share of the expected production.

Orbost gas plant details

The Orbost gas plant processed gas from the Patricia-Baleen that has ceased production and the Longtom field lying in the Gippsland Basin. The processed gas was supplied through the Eastern Gas Pipeline (EGP) to eastern Australia.

Cooper Energy plans to modify the plant, which has been put on maintenance, to process gas from the Sole and Manta gas fields lying in the Gippsland Basin and transport them via the EGP. The plant has a capacity of 90TJ/day.

Planned upgrades for the plant include the removal of mercury and hydrogen sulphide and additional gas compression during the processing phase.