Australia's 3D Energi has confirmed a gas-condensate discovery in the offshore Otway Basin following formation testing at the Essington-1 exploration well in permit VIC/P79.
The Otway Basin gas-condensate discovery was validated by confirming reservoir quality and deliverability, as both the primary Waarre A and secondary Waarre C reservoirs contain gas, in line with pre-drill expectations.
The company said that Ora formation testing was carried out across three zones in the Waarre A reservoir, a target with limited existing production and reservoir data compared to Waarre C.
This was the first deployment of Schlumberger’s Ora formation testing platform in Australia. Ora is designed to offer detailed information on the productivity of the reservoir while reducing operational and environmental impact.
According to the company, the results from Ora testing indicated that two out of three tested zones demonstrated effective reservoir quality and deliverability.
The third test targeted a zone with lower reservoir quality to determine the boundary for moveable gas.
Fluid samples were collected during this test, and the capture and composition are set to be verified onshore.
Analysis of fluids from downhole testing indicates gas condensate is present, with CO₂ levels between 3% and 4% across all tests, matching modular formation dynamics tester sample results.
The collected gas samples will be sent for lab compositional and pressure, volume and temperature analysis to assist with ongoing resource evaluation.
Deep transient testing was carried out on the Essington-1 Waarre A reservoir using the Ora formation testing platform.
Test one was placed in a low-quality argillaceous siltstone to assess the lower limit of moveable gas within the Waarre A reservoir.
The test showed “very low mobility and permeability”, with only limited radial flow observed, even after an extended test period.
This information will be used to further refine the assessment of the net productive reservoir as the geological model is updated and resource estimates are revised.
Tests two and three targeted intervals with moderate-to-excellent reservoir quality.
Both confirmed the moveable gas-condensate presence in sandstone units, with the second test indicating “very high mobility” and strong reservoir connectivity.
The third test, in a less favourable zone due to higher argillaceous content, is said to have still displayed “good mobility and moderate permeability”.
Together, these results suggest that the productive sections of the reservoir consist of laterally connected sandstone units with varying flow characteristics depending on sand quality and clay content.
The results from Ora will be combined with all formation evaluation data gathered during the Essington-1 drilling programme to refine the geological model, update resource estimates and examine possible commercialisation options.
Evaluation of the project's commercial viability will require consideration of all subsurface data, development plans, economic analysis, production forecasts and prevailing conditions in the market.
Essington-1 is scheduled to be plugged and abandoned as outlined in the approved Environment Plan. Following this, the Transocean Equinox rig will relocate around 20km north-west to begin drilling the Charlemont-1 exploration well.
3D Energi executive chairman Noel Newell said: “Ora testing has confirmed reservoir deliverability in key Waarre A intervals and delivered the type of high-quality subsurface data needed to progress our technical and commercial evaluation.
“This is the first time the Ora technology has been deployed in Australia, and its successful application has allowed us to acquire crucial reservoir insights while reducing environmental impact. We now shift our immediate focus to Charlemont-1 where we hope to replicate the outstanding results at Essington.”
