Patagonia Lithium has completed its latest Cilon drilling campaign with Well 8 delivering 2,043 litres per hour and rapid aquifer recovery, while a corrected estimate put the pumped lithium at a preferred 30kg. The result now feeds into a resource upgrade, but a disappointing Well 9 infill hole adds uncertainty about aquifer continuity.
- Well 8 reached 485 metres and returned lithium grades up to 232 mg/L
- 72-hour pump test produced 2,043 L/h, with recovery to static level within 24 hours
- Corrected estimate reduced inferred pumped lithium to a preferred 30kg, or 159kg LCE
- Well 9 ended in clay after one low-flow packer test and drilling has stopped
- $10.4 million cash balance and estimated 5.66 quarters of funding
Well 8 delivers the quarter's key flow result
Patagonia Lithium Limited (ASX:PL3) has finished its latest drilling push at the Cilon project in Argentina with one strong well and one clear warning. Well 8 reached 485 metres, produced 2,043 litres per hour during a 72-hour pump test and recovered from a drawdown of about 52.7 metres to its 3.64-metre static level within 24 hours.
The result builds on well 8 drilling results that previously showed lithium assays as high as 232 mg/L and packer flow rates of up to 705.9 L/h. Ten of 20 packer tests were successful, with the company identifying a broad sandy aquifer interval and arguing that flow is controlled more by transmissivity than by storage alone.
Corrected lithium estimate remains an inferred test result
The headline pump-test figure has been trimmed since the original announcement. Patagonia corrected the estimated lithium recovered from about 34kg, or 180kg of lithium carbonate equivalent, to a range of 29kg to 33.7kg, with a preferred estimate of 30kg, equivalent to 159kg LCE.
That figure is an assay-based estimate from the brine pumped during the test, not a resource or production measure. The correction reflected a revised understanding of the extraction depth and mixing during pumping: brine entered through the screen down to 477 metres, while the nearest packer sample was taken at 330 metres rather than 250 metres as first reported. The filing says the corrected assumption is 200-230 mg/L lithium.
Well 9 fails to confirm the target aquifer
The picture is less uniform at Well 9, an infill hole drilled without geophysics to test the extent of the aquifer observed at Well 2. Drilling stopped at 230 metres after the hole encountered roughly 50 metres of clay with gypsum veins. Only one packer test succeeded, flowing at 66.3 L/h with a specific gravity of 1.016.
Three core samples have been sent for assessment, but Patagonia says it will not continue drilling at that location. The result does not by itself settle whether the basal clays represent basement or a potentially water-bearing unit; the company has noted measured specific yields in comparable clays from Wells 5 and 6 and has passed the available data to Atacama Water Consultants for interpretation.
Resource upgrade becomes the next major test
With drilling complete, the Well 8 and Well 9 data will feed an upgrade to the existing 551,400-tonne LCE drainable mineral resource estimate, which is reported at an average grade of 294 mg/L lithium. The company also distinguishes that estimate from a previously cited 3.814 million-tonne total resource concept, so the figures should not be treated as directly interchangeable.
Four further Well 8 core results remain outstanding, alongside Well 9 assays and additional laboratory work intended to reconcile gamma-derived porosity with core analysis. The resource update is expected to precede a scoping study, while Ekosolve pilot testing is planned using brine from Well 2. Patagonia has also outlined a potential four-well production system supplying a 22,000 L/h lithium carbonate demonstration plant, though that remains a development plan rather than an operating asset.
Funding supports the next work programme
Patagonia held $10.41 million in cash at 30 September after raising $3.4 million in June and a further $8 million in August. Exploration and evaluation spending reached $1.222 million in the quarter, largely on Wells 8 and 9 and associated testing, while the Appendix 5B calculation puts estimated funding at 5.66 quarters based on the latest relevant outgoings.
Brazil provides a secondary exploration thread: the company has generated 25 rare earth and niobium targets across concessions 860164 and 860165 using its Logos workflow, radiometrics and hyperspectral data. Applications for auger and air-core drilling are planned, but the immediate investment question remains closer to home: whether the resource upgrade can convert Well 8's encouraging flow behaviour into a technically coherent and economically testable development case despite Well 9's poor result.
Bottom Line?
Well 8 has supplied the strongest technical evidence yet for continued Cilon evaluation, but the next resource estimate must reconcile its rapid recovery with Well 9's limited aquifer response.
Questions in the middle?
- Will the AWC resource upgrade expand the drainable estimate after incorporating Well 8's flow and porosity data?
- Do the remaining Well 8 cores and Well 9 assays clarify whether the aquifer is laterally continuous?
- Can Ekosolve pilot results and the scoping study establish credible economics for the proposed demonstration plant?