ADX Energy has reported encouraging flow test results from its Welchau-1 well in Austria, confirming the presence of light oil and gas condensate in the Reifling Formation. The company plans further testing to unlock the reservoir’s full potential.
- Positive flow testing confirms light oil and gas condensate at Welchau-1
- Acid stimulation performed but did not fully access fracture network
- Updip light oil accumulation mapped approximately 500 metres from well
- Reservoir characterized as overpressured with multiple appraisal targets
- Further testing planned including larger acid stimulation with coiled tubing
Testing Results and Reservoir Insights
ADX Energy Ltd (ASX:ADX) has provided an update on its ongoing appraisal activities at the Welchau-1 well in Austria, reporting positive results from flow testing within the Reifling Formation. The testing confirmed the presence of light oil and gas condensate, recovered during well unloading and sampling operations. The oil samples are consistent with an updip accumulation, approximately 500 metres from the well location, supporting the company’s interpretation of a significant light oil accumulation at the crest of the Welchau anticline.
The Reifling Formation, a 128-metre thick fractured carbonate reservoir, was subjected to acid stimulation designed to initiate flow. While the treatment successfully induced some inflow, it did not fully access the fracture network, resulting in a relatively small volume of fluid inflow and no stable pressure build-up to date. This suggests the reservoir’s fracture system remains only partially stimulated, prompting plans for further, more aggressive acid stimulation using coiled tubing.
Strategic Significance and Appraisal Potential
The Welchau structure is emerging as a strategically important hydrocarbon play, characterised by multiple appraisal targets including both the shallow light oil accumulation and deeper gas condensate potential. The reservoir is overpressured, with pressure and compositional data indicating a live petroleum system. The presence of light oil with minimal biodegradation and an overpressured system enhances the prospectivity of the accumulation, which lies near existing infrastructure, potentially easing future development.
ADX’s Executive Chairman, Ian Tchacos, highlighted the encouraging nature of the results, noting that the testing supports the interpretation of a large, light oil accumulation updip of Welchau-1, alongside promising deeper gas condensate potential. He emphasised the ongoing work to better understand the reservoir’s characteristics and the company’s commitment to advancing appraisal activities.
Environmental and Regulatory Context
Testing activities had previously been interrupted by environmental objections but were allowed to resume following a ruling by the Austrian Administrative Court in late 2025. This clearance has enabled ADX to continue its testing program, which remains ongoing with further pressure monitoring and sample analysis underway. The company is evaluating options for larger acid stimulation treatments to improve reservoir access and flow rates.
Looking Ahead
ADX plans to continue monitoring reservoir pressure and fluid inflow, with further testing designed to unlock the full potential of the Reifling Formation. The company is also considering appraisal drilling options, including side-tracking or deepening wells to target both the light oil and gas condensate zones. These steps will be critical in defining the commercial viability of the Welchau discovery and its potential contribution to ADX’s portfolio.
Bottom Line?
ADX’s Welchau-1 results mark a promising step forward, but unlocking the reservoir’s full potential will require further targeted testing and appraisal.
Questions in the middle?
- Will the planned larger acid stimulation successfully access the full fracture network?
- How will ongoing pressure monitoring influence the assessment of reservoir connectivity and size?
- What timeline and investment will be required to advance appraisal drilling and commercial development?