Drilled to 2,527 m, the well penetrated the top of the target reservoir 2 m higher than prognosis at 2,503 m. The bottom 24 m of the well consists of oil-bearing F3 sands, which were at a higher-than-expected reservoir pressure resulting in an influx of fluid into the well.
As part of the operations to remove the influx, oil was recovered at the surface from the well and appears similar in nature to Sea Lion crude, the companies say. Also confirming the discovery are logging data collected over the first 12 m of the reservoir and cuttings data to the base of the well comprising oil stained sandstones.
Well operations will be suspended before the planned total depth is reached. The rig will be released to drill in the South Falkland basin, and is expected to return to continue operations in the North Falkland basin in August.
Premier says it’s now considering the optimal appraisal program for the Elaine-Isobel complex in PL004. In April, well 14/15b-5 of the Zebedee prospect on PL004b cut 81 ft of net oil pay and 55 ft of net gas pay in the Cretaceous F2 and F3 formations (OGJ Online, Apr. 2, 2015).
Referring to Isobel Deep, Andrew Lodge, Premier exploration director, said, “The well has successfully demonstrated a trapping mechanism and the presence of moveable oil in the Elaine-Isobel fan complex.”
Sam Moody, Rockhopper chief executive officer, noted, “Having retained the subsurface lead for North Falkland basin exploration in the farmout to Premier in 2012 (OGJ Online, July 12, 2012), Isobel represents a new play and significantly derisks the entire Isobel-Elaine fan complex confirming the presence of an oil-prone hydrocarbon system with moveable oil in the Isobel Deep reservoir.
“Although the well has not yet reached total depth the signs for the Isobel-Elaine complex so far are very encouraging and we will decide the next actions in appraising the discovery over the coming weeks while the rig is drilling to the south of the Falkland Islands,” Moody said.