Cooper Energy has found gas 9km offshore Victoria, Australia, which the company claims is the first new Otway Basin gas field discovery from offshore drilling in 11 years.

Annie-1 is the first offshore gas exploration well that Cooper has drilled in Australia and the initial well of an $80m drill campaign with a subsidiary of Japan’s Mitsui Group. The field is situated between the producing Henry (15km west) and depleted Minerva (11km east) gas fields.

The Annie-1 exploration well reached a total depth of 2,442m, encountering a gross gas column of 70m with gas-on-rock at its base.

If Cooper Energy and Mitsui E&P Australia decide to go ahead with development, the Annie well is expected to start gas production in the second half of 2021. Both the companies currently produce gas from the nearby Casino, Henry and Netherby fields.

Cooper Energy said data collected in Annie-1 is consistent with adjacent analogue producing fields. Laboratory analysis is set to be carried out for confirming gas composition. Cooper Energy managing director David Maxwell noted that preliminary analysis of the geological data from Annie-1 was consistent with the mid-range of the pre-drill estimates.

Maxwell said: “In the coming months, we will complete the subsurface assessments and analysis of data to refine our estimates of field size and to inform decisions regarding field development.”

Cooper Energy said the Diamond Offshore Ocean Monarch drilling rig will now start preparations to plug and abandon Annie-1, consistent with the earlier unveiled work programme. The rig is due to move to drill the second well in the two well programme, Elanora-1 in VIC/L24, 23km southwest of Annie-1.