P2252 - Pesacola14 Nov 2020 09:07
The first well drilled in the licence area was 41/10-1, operated by Marathon in 1994/5 to test the Carboniferous (Figure 2.2). It had gas shows, and possibly thin gas pay, in the Zechstein Hauptdolomite and Plattendolomite but the underlying lower Carboniferous (Dinantian) was dry with minor gas shows. An 800 m Carboniferous clastic interval was encountered with locally high net sand intervals. Porosities were reasonable in the upper section, but deteriorated with depth to approximately 5% at 3000 m. Net gas pay of 8 m has been interpreted by Wintershall[9] in the Platten and Hauptdolomites but none of the intervals were tested. A small closure may exist at these levels (Figure 2.5).
The blocks (as licence P1129) were awarded to Walter UK (E&P) Ltd in 2003. Walter operated the 41/5-1 well drilled in 2004 into the top 30 m of the Carboniferous (Figure 2.3). The well encountered Namurian sandstones but logs were poor without gas shows. The well suffered a near catastrophic failure of the Hauptdolomite reservoir with consequent loss of mud and the damaging of the shallower Plattedolomite reservoir. Gas shows were encountered throughout most of the Hauptdolomite and Plattendolomite on mud logs but the logs were unavailable for inspection and suffered from poor hole conditions. Significant mud losses and gas shows occurred in the Hauptdolomite indicating localised high, porosity and permeability.