ADX Energy (ASX: ADX) says its successful Welchau-1 gas well in Austria is being wound up and prepared for conditioning, casing-off and suspension for future flow testing. Despite not managing to collect a downhole sample due to a sample tool getting stuck, the company says it nonetheless still saw both gas and condensate flowing to surface and plenty of evidence of “network fracturing” and “vuggy porosity”, both of which point to potential flow success.
ADX says it will now use the big E200 drilling rig onsite to run more casing downhole to protect the areas of interest ahead of returning later this year with a smaller, more economical workover rig to flow test the well. Local environmental permits only permit drilling and well testing from October to March and ADX says it has plenty of drilling, coring and logging evaluation work to do ahead of October when it will be back on the well again with a view to flow testing it.
The company says well logging indicates a strong correlation between the observed Steinalm carbonate target formation, network fracturing and vuggy porosity with hydrocarbon shows in drill chips, supported by condensate and gas inflows at surface while drilling and attempting to pull out the stuck tool.
Most of the recent activity at the well has centred on hole conditioning, running wireline logs, downhole pressure recording, sampling and tool recovery.
In addition to the logging, the program acquired a 7m core sample from the target formation which also clearly shows a high degree of open fracturing in a vuggy carbonate matrix and evidence of hydrocarbons.
Notably the fracture networks were recorded across a stellar gross interval of 356m of potential productive zones, which will no doubt create a level of market anticipation ahead of the re-start in October.
Those potential productive zones are quite shallow too, occurring from just 1346m to 1702m across three interpreted lithological sequences. The main target Steinalm Formation was logged from 1458m to 1557.4m and exhibits the greatest incidence of fracturing, porosity and permeability.
Similar fracturing, porosity and vuggy characteristics are recorded in the overlying Reifling Formation and the underlying Guitenstein, and Reichenall Formations, but to a lesser degree and this is reflected by their lower permeabilities.
Encountering potential productive zones over a gross interval of 356 metres is very compelling. While it is frustrating that attempted fluid sampling was hampered by operational difficulties, relatively common in fractured carbonate reservoirs, the well inflow of hydrocarbons further confirms the existence of mobile gaseous and liquid hydrocarbons which can only be properly evaluated with a cased hole testing program.
ADX Executive Chairman, Mr Ian Tchacos
ADX says several good hydrocarbon shows with gas peaks as high as 8.22 per cent were recorded in the reservoir formations below the sealing Lunz and Partnach Formations, accompanied by liquid hydrocarbon shows which include direct and cut fluorescence on cuttings and core fragments.
ADX clarifies that in core fragments, the fluorescence is clearly associated with the presence of fractures.
The company says its pressure recording and sampling of the formation was undertaken using a modular formation dynamic tester (MDT), a downhole instrument designed to make real-time flowline resistivity measurements to discriminate between formation fluids and filtrate from water- and oil-based muds.
It says five pressure recordings from the interval between 1479m to 1597m (118m) revealed a complex carbonate reservoir setting in an over-pressurised hydraulic system at an equivalent formation density (specific gravity or SG) of 1.28.
Additionally, the corresponding permeability of the pressure-tested levels shows medium to very high permeability and the recordings are consistent with observed fracture densities and interpretations of petrophysical logs.
ADX says it also plans to kick off a more detailed mapping program to follow up on prospective structures it has already recognised within its acreage.
Notably, ADX says its Welchau-1 project is well positioned to take advantage of any commercial discovery of hydrocarbons with both gas infrastructure and a condensate refinery within striking distance.
Despite some minor technical setbacks Welchau-1 has already ticked a lot of boxes and with hydrocarbons already flowing to surface, the market meerkats will no doubt be watching closely in October when the company attempts to formally flow test the well.
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