Production testing at Vintage Energy’s (ASX: VEN) Nangwarry-1 carbon dioxide well in South Australia’s onshore Otway Basin has confirmed gas flowing at a higher rate than previous commercial rates in the region.
The well was perforated across the Top Pretty Hill formation and is reported to have produced gas at “higher than anticipated rates” of 10.5-10.8 million standard cubic feet per day through a 48/64-inch choke at a flowing wellhead pressure of 1,415 pounds per square inch (psi) over a 36-hour period. The flow was measured through a 3-inch 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 explorer reported.
Resource estimate revision now underway
At present, the current gross recoverable estimates for Nangwarry-1 carbon dioxide are 7.8 billion cubic feet (low), 25.1Bcf (best), and 82.1Bcf (high). These estimates were made prior to the production test but with recognition that the estimated 98m gas column could be greater.
In today’s announcement, Vintage said the latest testing has confirmed a gas column of at least 120m, which is expected to result in increased recoverable estimates.
Consequently, data has been provided to the independent assessor ERC Equipoise and a resource estimate update is in progress.
Recoverable volumes interpreted to sit in mid to high range
In addition, no significant pressure drop was interpreted in the reservoir during the flow testing which Vintage said indicates a “sizeable volume” of carbon dioxide 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 carbon dioxide greater than the low estimate and falls in the mid or higher end of the pre-test volumetric estimates,” the company reported.
“This provides a high level of confidence needed to commence planning for development of this resource,” it added.
Nangwarry retention licence approved
Subsequent to the successful drilling and testing of Nangwarry-1, South Australia’s Department of Energy and Mining has approved an application for a retention licence (PRL 249) over the Nangwarry carbon dioxide discovery.
The application was approved prior to the 5 May expiry of PEL 155, which had been held in a 50-50 joint venture by Vintage and non-listed operator Otway Energy.
This means the joint venture still retains a significant amount of land around the Nangwarry field while it establishes a case for commercial development.