2021 Annual Report
Cooper/Eromanga Basins, Queensland and South Australia
Vintage 50% and operatorship, Metgasco Ltd 25% and Bridgeport (Cooper Basin) Pty Ltd 25%
The Vali-1 ST1 flow test program was carried out safely and as planned, delivering a stabilised gas flow of 4.3 MMscfd through a 36/64"choke at a operations flowing well-head pressure ("FWHP") of 942 psi over a two-day period from the Patchawarra Formation. Transient tests were also undertaken with rates recorded between 3.7 MMscfd (through a 24/64" choke at 1,676 psi FWHP) and 7.5 MMscfd (through a 32/64" choke at 1,593 psi FWHP).
Strong flow rates were achieved during all flow periods and quick pressure build-ups observed during all shut-in periods, with pressure levels quickly approaching around 3,000 psi. All flow rates were restricted through varying choke sizes to ensure proppant was not returned from the formation into the well bore, therefore avoiding any reduction in the effectiveness of the stimulation process.
During the flow testing of Vali-1 ST1, the following activities were undertaken:
- Production Logging Tool ("PLT") was run, which determined that gas was being contributed by each of the stimulated zones
- Shut-ins, which observed the pressure response of the reservoir, with pressure readings reaching 2,932 psi at the end of the recording period and continuing to build
- Flow testing, with transient tests undertaken under various choke sizes of 24/64", 32/64" and 40/64" over three equal periods of six hours
- Gas samples taken, with the composition in line with typical Cooper Basin Patchawarra wells
Cultural heritage and environmental surveys were completed in ATP 2021 for the surface facility, flowline and possible future well locations. The process was completed in a safe and timely manner with the Wongkumara People, Erias/environmental projects and GPA/FYFE and we appreciate and thank all parties for their efforts.
Vali-2 was drilled to total depth at 3,240 metres, with no safety incidents, and cased for production. Wireline logging confirmed a new gas pool in the Toolachee Formation and confirmed gas in the Patchawarra Formation and Tirrawarra Sandstone.
A gas gradient was established in Vali-2 through MDT pressure measurements and a gas sample was recovered. Analysis of the sample indicates the Toolachee gas has a higher percentage of hydrocarbons at 82% (75% methane, 4% ethane, 3% other hydrocarbons) and 18% inert gases, compared with the Patchawarra gas in Vali-1 ST1, which has around 76% hydrocarbons and 24% inert gases. The wireline logging and MDT results indicate the Toolachee reservoir could flow without the need for fracture stimulation.
The Patchawarra Formation has both conventional and low permeability net gas pay distributed over 18 sandstone packages, with production from the Patchawarra to likely be optimised by fracture stimulation.
Vali-3 reached total depth at 3,186 metres, with no safety incidents, and cased for production (in July 2021). The main objective of Vali-3 was achieved following the intersection of the Patchawarra Formation in line with the pre-drill interpretation of the Vali structure.
During drilling, gas shows were observed in the lower Nappamerri Group, Toolachee, Epsilon and Patchawarra Formations, and the Tirrawarra Sandstone. Samples collected from the Nappamerri Group and Toolachee Formation during the evaluation program were analysed to determine gas pay in the sands in these zones.
Oil shows were observed through the late Cretaceous, Jurassic and Triassic sediments, as well as the uppermost Permian aged Toolachee Formation. Similar shows were encountered in both the Vali-1 ST1 and Vali-2 wells and are a major positive in terms of oil potential, with 14 oil leads identified in ATP 2021. Despite there being no mappable Jurassic structural closure around the three Vali wells, a particularly good oil show was observed within the McKinlay Member in Vali-3 and sampling recovered water, likely mud filtrate, with hydrocarbon odour and blue-white oil fluorescence.
This suggests that oil has migrated through this area and increases the prospectivity of the Jurassic structural closures nearby.
The Joint Venture now has three cased wells in the Vali Field available for future gas production.
While the main objective of the Vali-2 and Vali-3 drilling program was to appraise the extent of the Patchawarra Formation gas discovery in Vali-1 ST1, the discovery of a new gas pool in the Toolachee Formation has provided material upside. The Joint Venture is now progressing plans for production from these successful Cooper Basins wells, with the ACCC granting final approval for the joint marketing of gas from the Vali Field.
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About Vintage Energy Ltd
Vintage Energy Ltd (ASX:VEN) has been established to acquire, explore and develop energy assets principally within, but not limited to, Australia, to take advantage of a generally favourable energy pricing outlook.
Vintage Energy Ltd