ADX Energy has restarted flow testing at its Welchau-1 well in Austria after regulatory delays, aiming to confirm the commercial viability of light oil and gas-condensate reservoirs in the Reifling Formation.
- Resumption of Welchau-1 well testing after environmental clearance
- Focus on acid stimulation to overcome formation damage in fractured carbonate reservoirs
- Confirmed presence of light oil and gas-condensate with strong pressure connectivity to Molln discovery
- Refined structural model indicates expanded appraisal potential across multiple reservoirs
- ADX holds 75% economic interest in the ADX-AT-II permit in Austria
Regulatory Clearance Enables Testing Restart
After a pause triggered by environmental objections from non-governmental organisations earlier in 2025, ADX Energy Ltd (ASX – ADX) has received clearance from the Austrian Administrative Court to resume testing at its Welchau-1 well. This well, located within the ADX-AT-II permit in Austria’s Northern Alps, is a key asset for the company’s European exploration portfolio.
The interruption had stalled progress on evaluating the Reifling Formation, a shallow fractured carbonate reservoir that is one of four primary reservoirs intersected by the well. The court’s ruling has allowed ADX to proceed with a carefully planned acid stimulation program designed to overcome drilling-related formation damage and enhance reservoir productivity.
Technical Focus on Reifling Formation
The Reifling Formation is interpreted to host a light oil accumulation near the updip crest of the Welchau anticline, approximately 500 metres westward from the well’s current position. Acidisation, a long-established technique in carbonate reservoirs, will be employed to improve flow characteristics by dissolving formation damage and increasing permeability.
Following acid injection and soak periods, the well will be flowed back and monitored to assess natural hydrocarbon production. If initial flow rates are insufficient, swabbing will be used to induce fluid movement. The testing aims to quantify hydrocarbon content, flow potential, and reservoir connectivity, which are critical for determining commercial viability.
Encouraging Reservoir and Pressure Data
Welchau-1 has intersected over 450 metres of fractured carbonate reservoirs, with three primary zones considered promising for appraisal. Light oil has been recovered from downhole sampling, and pressure data confirm extensive communication between Welchau and the nearby Molln gas-condensate discovery. This connectivity suggests a robust petroleum system with significant condensate resources and an active aquifer supporting reservoir pressure.
ADX’s updated geological and structural modelling has refined the interpretation of the Welchau anticline, indicating the reservoir crest lies further west than previously thought. The model also delineates a duplex thrust-related system beneath the well, which may host additional overpressured gas-condensate reservoirs accessible through sidetracking or well deepening.
Strategic Implications and Next Steps
Holding a 75% economic interest in the ADX-AT-II permit, ADX Energy is strategically positioned to advance its European exploration ambitions. The resumption of testing at Welchau-1 marks a critical phase in appraising the light oil and gas-condensate potential of this underexplored region.
The company has committed to providing further updates as flow testing progresses and geological modelling evolves. Investors will be watching closely for flow rates and reservoir performance post-acid stimulation, which will ultimately determine the commercial prospects of the discovery.
Bottom Line?
ADX’s Welchau-1 testing restart could unlock a significant new European hydrocarbon resource, but commercial success hinges on upcoming flow results.
Questions in the middle?
- Will acid stimulation deliver sustained flow rates sufficient for commercial development?
- How might ongoing environmental and regulatory factors impact future operations at Welchau?
- What is the potential scale of the overpressured gas-condensate reservoirs identified beneath Welchau?