Falkland Islands explorer Borders & Southern Petroleum reported Monday that it is abandoning its Stebbing well in the South Falkland Basin because anomalous pressure conditions meant it was unable to reach the deeper zones it was targeting.
The Stebbing well (61/25-1) was drilled to a total measured depth of 10,040 feet and encountered "very strong gas shows" in the Tertiary section of the drill. Petrophysical analysis of the wireless logs suggest and interval of thin-bedded siltstones and claystones with a net-to-gross of 36-percent and an average porosity of 19 percent.
However, Borders said that due to the thin-bedded character of this sequence it was not possible to obtain a clear indication of the fluid type or saturation. Although the geophysical anomalies identified on seismic are coincident with this zone containing hydrocarbons, Borders’ initial assessment is that this upper target is unlikely to be commercial.
Strong gas shows continued below the upper target, but progress was slow due to lost circulation and well flows that occurred in consecutive hole sections. On each occasion the well was successfully controlled it became necessary to set additional strings of casing, using the contingency casing considered in the well design. In the final six-inch hole section, the fluid pressures continued to rise, giving further well flows and it became impossible to continue drilling while maintaining well integrity.
Consequently, Borders took the decision to cease drilling and now intends to plug and abandon the well. The Leiv Eiriksson rig (DW semisub) used for the Stebbing drill will now be handed over to Falkland Oil and Gas for its own drilling program.
In spite of the Borders' "significant" gas condensate discovery at Darwin in late April, the news of the abandonment of Stebbing was disappointing to the firm’s investors. Borders' shares are traded on London's Alternative Investment Market, where they fell by more than 70 percent in early trading on Monday morning.
Brendan Long, an oil analyst at London-based Merchant Securities, commented that he believed "the fortunes of the company are substantially dependent on the forthcoming conclusions" of laboratory analysis of fluid samples taken from the Darwin discovery.
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