The Cooper/Eromanga Basins are the premier onshore oil and gas producing basins in Australia. The Cooper Basin is a Permo-Carboniferous to Triassic basin with sediment up to 2,500 metres thick which consists of interbedded sandstones, shales and coals. The overlying Eromanga Basin is Early Jurassic to Late Cretaceous in age and has sediment up to 3,000 metres thick which consist of sandstones, siltstones and shales. Over 2,500 exploration and development wells have been drilled in the Cooper/Eromanga Basins to date with estimated cumulative production of over 6.2 Tcf of gas, 315 MMbbl of oil and 92 MMboe of condensate.
The Cooper/Eromanga Basins are connected to the Adelaide and east coast markets via gas pipelines, with oil and liquids pipelines connecting the region to Port Bonython in South Australia and Moonie/Brisbane in Queensland.
The Vali-1 ST1 well was drilled during December 2019 and January 2020 and discovered gas in the primary Patchawarra Formation target. The well reached a total depth (“TD”) of 3,217 metres measured depth, in basement, on 10 January 2020. This was followed by an evaluation program that included wireline logging, the gathering of formation pressure data and the sampling of formation fluid. Analysis of the data gathered indicated the discovery of over 80 metres of interpreted log net gas pay (porosity cut-off of 6%) over a gross 312 metre interval in the Patchawarra Formation target. The Patchawarra Formation was the primary target for the well. As with other similar wells in the Cooper/Eromanga Basins, stimulation is being considered by the joint venture as a method to increase permeability and flow rates in the Patchawarra sandstones.
Potential gas pay was also calculated in the secondary Toolachee target and the Triassic age Nappamerri Group, with oil shows observed in the Jurassic age Westbourne and Birkhead formations. In addition to recovering gas from the Patchawarra Formation via MDT sampling, gas was also recovered from the Nappamerri Formation. The Vali-1 location is mapped at the edge of, or just outside of structural closure for these reservoirs, indicating significant gas and oil potential as mapped up-dip of the Vali-1 location at these levels. There are also numerous Jurassic structures mapped within the permit which will now be high-graded due to the strong indications of oil migration into the Jurassic level in this well.
Vali-1 ST1 has been cased and suspended for stimulation and flow testing to confirm the capability of the reservoir to produce gas at commercial flow rates. Once confirmed, a gas contract will be negotiated, and the well will be tied into nearby infrastructure. With the permit being in close proximity to pipelines and facilities, it is anticipated that the Vali gas discovery will be fast tracked to market.
Vintage has a 50% interest and operatorship in ATP 2021, which was achieved through the following steps:
ATP 2021 represents an excellent entry for Vintage into the prolific Cooper/Eromanga Basins. The 370 km2 permit on the southern flank of the Nappamerri Trough is partly covered by 2D seismic of varying vintages, while the southern section of the Permit (~115 km2) is covered by the Snowball 3D seismic survey acquired in 2016. Kinta-1 was drilled in 2003 and is the only well, other than Vali-1 ST1, to be drilled within ATP 2021. Kinta -1 was an uneconomic gas discovery, but with the application of modern drilling practices, it is expected that performance from future wells will be significantly improved. Substantial oil and gas discoveries within 20 kilometres of the permit include the Dullingari, Epsilon, Beckler/Bow/Crowsnest, Roseneath and Wolgolla fields, with production in the order of ~600 Bcf of gas and 11 MMbbl of oil.
Several structural closures are mapped on the 3D seismic within ATP 2021 in the Patchawarra, Toolachee and Namur/Murta formations. The largest of these is the Vali structure (covering an estimated area of 10.8 km2) which the joint venture drilled at the end of 2019. The Vali structure is a four-way dip structural closure in the Permian sediments.
|Vali Net Contingent Resources (Bcf)|
Notes: 1. Gas In Place and Contingent Resource estimates reported here are ERCE estimates; 2. Gross Contingent Resources represent a 100% total of estimated recoverable volumes; 3. Resource estimates have been made and classified in accordance with the Petroleum Resources Management System (“PRMS”). 4. Net Contingent Resources attributable to Vintage represent the fraction of Gross Contingent Resources allocated to Vintage, based on their 50% interest in ATP 2021; 5. Volumes reported here are “unrisked” in the sense that no adjustment has been made for the risk that the project may not be developed in the form envisaged or may not go ahead at all (i.e. no Chance of Development factor has been applied); 6. Chance of Development for the Contingent Resources shown here has been estimated to be 85% by Vintage and agreed by ERCE. This is based on proximity to existing infrastructure, development of similar reservoirs by adjacent fields and high downstream gas demand; 7. Contingent Resources have been sub-classified as “Development Unclarified” under the PRMS by ERCE; 8. Contingent Resources volumes shown have had shrinkage applied to account for CO2 and include only hydrocarbon gas. No allowance for Fuel & Flare has been made; 9. ERCE GIIP volumes & Contingent Resources presented in the tables are the probabilistic totals for all 19 Patchawarra reservoir intervals; 10. Probabilistic totals have been estimated using the Monte Carlo method.
Vintage executed a binding farm-in agreement for PRL 211 on the South Australian side of the Cooper/Eromanga Basins. Under the proposed joint venture, Vintage will become the operator with Senex to be free carried through the drilling of the first well. PRL 211 is a 98.49 km2 retention licence that is close to infrastructure and has an initial five-year term expiring in October 2022, with an option to renew the permit for a further five years. The licence is located immediately adjacent to ATP 2021.
The main target in PRL 211 is the Odin structure, which is fully covered by recent 3D seismic and has gas potential in the Patchawarra and Toolachee formations. Odin is located on the southern flank of the Nappamerri Trough near the producing reservoirs at the Bow, Beckler and Dullingari gas fields and is immediately adjacent, and similar in form, to the Vali gas discovery. Stratigraphic upside, like that seen in the Beckler-Bow field area, is also possible at Odin. The Odin prospect straddles the border between PRL 211 and ATP 2021.
Under the terms of the farm-in, Vintage, Bridgeport and Metgasco will drill a well into the Odin structure (with Vintage paying 50% of the estimated cost of the well – approximately $2.25 million contribution by Vintage for 42.5% equity). All further work, including the potential to stimulate and flow test the Odin well, will revert to the equity share of the joint venture. Drilling of the Odin well is targeted to take place in 2020.
The farm-in is subject to a number of conditions, including Ministerial approvals, confirmation that PRL 211 will remain part of Senex's PRL scheme group, the farm-in parties demonstrating that between them there are sufficient funds available to drill the well, and negotiation and execution of formal farm-in and joint venture documents.
|Total Odin Structure Gross Prospective Resource (Bcf)1|
|1U low estimate||2U best estimate||3U high estimate|
|Net to Vintage||1.6||5.7||19.0|
1. Net to Vintage is the total of 42.5% of the prospective resources in PRL 211 and 50% of the prospective resources in ATP 2021. Volumetrics estimated by Vintage. The estimate quantities of petroleum that may potentially be recovered by the application of a future development project(s) relate to undiscovered accumulations. These estimates have both an associated risk of discovery and a risk of development. These prospective resources were first reported to the ASX on 22 November 2019. Further exploration, appraisal and evaluation is required to determine the existence of a significant quantity of potentially moveable hydrocarbons. The resources have been classified and estimated in accordance with the Petroleum Resource Management System (PRMS). The prospective resources have been estimated based on the interpretation of 3D seismic integrated with offset well data. Probabilistic methods have been used to estimate the prospective resource in individual reservoirs and the reservoirs have been summed arithmetically. Vintage is not aware of any new data or information that materially affects the estimate above and that all material assumptions and technical parameters continue to apply and have not materially changed. Resource estimates are net of shrinkage.