Borders & Southern reports results from its Stebbing well. Well 61/25-1 was drilled to a total measured depth of 3060m (true vertical depth of 3011m). The well penetrated the upper Tertiary target on prognosis but was unable to reach lower targets due to anomalous pressure conditions. The lower targets remain unevaluated.
The well encountered very strong gas shows (C1 to C5) whilst drilling the Tertiary section. Petrophysical analysis of the wireline logs suggest an interval (2500m to 2651m) of thin bedded siltstones and claystones with a net to gross of 36% and an average porosity of 19%. Due to the thin bedded character of this sequence it was not possible to obtain a clear indication of the fluid type or saturation. The geophysical anomalies identified on seismic are coincident with this zone containing hydrocarbons. The initial assessment is that this upper target is unlikely to be commercial although further technical evaluation is required.
Strong gas shows continued below the upper target. However, progress was slow due to lost circulation and well flows which occurred in consecutive hole sections. Several of these flows contained gas. On each occasion the well was successfully controlled but it became necessary to set additional strings of casing, using the contingency casing considered in the well design. In the final 6″ hole section, the fluid pressures continued to rise giving further well flows and it became impossible to continue drilling whilst maintaining well integrity. A decision was therefore made to cease drilling.
It is very disappointing not to have reached all the potential reservoir targets in this well. The geological and engineering data will now be reviewed in detail in order to understand the complexities of this prospect.
The Company now intends to plug and abandon the well in line with regulatory requirements and assign the rig to Falkland Oil and Gas. An announcement will be made once this has been completed.
Fluid samples from the Darwin discovery are undergoing analysis in the lab and the results are on track to meet the previously reported 10 week timeframe.
Press Release, July 16, 2012