Vintage Energy Ltd (ASX: VEN, “Vintage”) provides an update on the Nangwarry CO2 field in the onshore Otway Basin.
Nangwarry-1 was perforated across the Top Pretty Hill Formation and produced gas at higher than anticipated flow rates of 10.5-10.8 million standard cubic feet per day (“MMscfd”) through a 48/64” choke at a flowing wellhead pressure of 1,415 psi over a 36-hour period. This flow was measured through a 3” orifice plate and choked back to analyse the well over this extended flow period with stable conditions. The well is very productive, with this flow rate well in excess of previous commercial flow rates in the region.
The current gross recoverable estimates for Nangwarry-1 carbon dioxide are: Low of 7.8 Bcf (3.9 Bcf net), Best of 25.1 Bcf (12.6 Bcf net), High of 82.1 Bcf (41.1 Bcf net) (refer ASX release dated 31 August 2020). These estimates were certified by ERC Equipoise (ERCE).
ERCE’s estimates were made prior to the production test, using a gas column of 98 metres, but recognising that this column could be greater. The Joint Venture is extremely pleased that the latest testing confirmed a gas column of at least 120 metres, which should result in increased recoverable estimates. This update is in progress, with data already provided to ERCE.
Following analysis of the main flow test data, and pressure build-up data after an extended shut in of the flow, Vintage has interpreted that there was no significant pressure drop in the reservoir as a result of the flow. As the flow test had negligible impact on the reservoir pressure, this indicates a sizeable volume of CO2 is present in the field. Based on this interpretation of the data, and the volume of gas produced during the test, it is considered that Nangwarry-1 has accessed a volume of CO2 greater than the low estimate (detailed above) and falls in the mid or higher end of the pre-test volumetric estimates. This provides the high level of confidence needed to commence planning for development of this resource.
Since the successful drilling and testing of Nangwarry-1, the Department of Energy and Mining approved an application for a retention licence over the Nangwarry CO2 discovery, prior to expiry of PEL 155 on 5 May 2021. As a result, the Joint Venture retains a significant amount of land around the Nangwarry Field while it establishes a case for commercial development.