ADX gears up to flow test Austrian oil and gas discovery

ADX Energy is gearing up to start crucial flow testing operations in the next week at its Welchau-1 discovery well in Upper Austria.

RED Drilling & Services, engaged by ADX as its operator of workover rig W-102, was mobilised to site three weeks ago and is now in the final stages of running a test string which includes tubing, packer and perforating equipment to prepare the well for tubing conveyed perforation. The technique is designed to deliver a perforating gun to access the hydrocarbon reservoirs safely and accurately.

All the needed ancillary facilities at surface including a test separator, pipework and the production storage tanks are, importantly now nearing completion.

The testing program has been developed to focus on reservoir fluid type, the flow capacity and ultimately determine the size of the reserves.

ADX will start by flow testing the Steinalm formation, aiming to minimise any potential damage to the shallower Reifling formation which will be subsequently tested.

By using a series of flow periods and shut-ins, the company will be eagerly awaiting to see how the well performs as well as checking for any potential reservoir damage caused by drilling and cementing the 7-inch casing.

Initially, flow rate, surface pressure and downhole pressure data will be collected alongside samples from both levels. However, plans may also include well-testing under stimulated conditions to gauge potential improved performance.

Although the Steinalm formation tests could take from 6 to 10 weeks, if a good flow is achieved, ADX may stretch the timeline further to gather more long-term data.

The Welchau-1 discovery made headlines when it was first drilled in March, with hydrocarbon indications spanning a 450-metre interval and intersecting three primary reservoirs. Preliminary tests before casing suggested a substantial gas discovery with condensates, estimated to hold between 12 and 217 million barrels of oil equivalent (MMBOE), with a mean estimate of 85 MMBOE.

In a significant turn of events, ADX then reported in September it believed the hydrocarbons discovered at Welchau are actually now primarily high-grade, light oil with associated gas—a valuable shift from the initially expected liquids-rich gas.

The company still holds a 75 per cent economic interest in the Welchau-1 discovery and part of a wider ADX-AT-II license area after it farmed a 25 per cent stake out to Austrian giant MCF Energy in exchange for 50 per cent of the Welchau-1 well expenses up to a cap of €5.1 million.

MCF has now locked in the 25 per cent stake via the funding obligations it has already met. The compay also remains on the hook for any additional well costs including exploration and appraisal expenses.

With its Vienna fields in Austria now expected to ramp up net production levels by more than 50 per cent to 340 barrels of oil equivalent per day (BoEPD) after announcing in September that it would shortly be bringing Anshof-2A onstream in December, a successful flow test at Welchau-1 in the ADX-AT-II license area would certainly cap off a stellar year for the ADX.

2025 promises to be just as busy with no less than seven high quality targets to chase up in its ADX-AT-II license area including the promising Rossberg lead to the north. Two further reservoirs in the basement of the Welchau-1 well, sitting below the current seven-inch casing at a depth of 1,733m and identified during the initial discovery in April also require testing.

Notwithstanding the disappointing result of its latest Licht-1 wildcat well a week ago, which intercepted gas but not in sufficient quantities to be commercial, ADX still has plenty of irons in the fire and is rapidly proving the Upper Austrian region is rich pickings for oil-and-gas explorers.

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