Uchenna Izundu
International Editor
LONDON, Nov. 27 -- Sterling Resources Ltd., Calgary, has tested the Breagh appraisal well, drilled on Block 42/13 in the UK southern North Sea. The well flowed without stimulation at 17.6 MMscfd of gas through a 56/64-in. choke. Following an additional 12-hr flow period at a controlled rate of 14.3 MMscfd against a flowing wellhead pressure of about 1,550 psi, Sterling shut in the well for a pressure build-up survey.
Ensco International Inc.'s Ensco 85 jack up spud the Breagh appraisal well Sept. 25 (OGJ Online, Sept. 24, 2007). It was drilled to 8,047 ft TD, and open-hole logs confirmed a gas-bearing Carboniferous section with an estimated 76 ft of net pay, Sterling said. The perforations were across an interval of 7,332-7,447 ft, and the rates recorded are at the top end of the prewell estimates, Sterling said.
Operator Sterling holds a 45% stake in the well.
"A significant part of the Breagh story was the ability to prove that a new well could be drilled and tested without damaging the reservoir section, and this in turn would lead to test rates significantly higher than those achieved in the 1997 discovery well," said Sterling Chief Executive Officer Stewart Gibson.
Partner EnCore, which holds a 15% interest in the well, said the appraisal well encountered a possible gas-water contact in line with the original 42/13-2 discovery well, giving a gross gas column of 460 ft.
"These results also bode well for the potential of the East Breagh structure, which could provide significant additional gas volumes," said Alan Booth, EnCore's chief executive officer. The prospectivity risk in surrounding acreage is less now, he said.
Sterling holds working interests ranging from 60-100% in the eleven blocks surrounding Breagh, which are mapped as having significant prospectivity.
"Based on preliminary analysis completed since the well results were obtained, the correlation of certain geological features between the original 42/13-2 discovery well drilled in 1997 and the 42/13-3 well is encouraging," said Sterling. "In particular, the presence of good quality sand in the more crestal 42/13-3 location is significant and may suggest that this upper sand-prone section, which has better reservoir quality, has a widespread distribution.
"The net thickness noted in the 42/13-2 and 42/13-3 wells, which are 1.5-km apart, is consistent with the potential for considerable gas volumes within the area currently mapped as West Breagh," Sterling added. It said further significant potential is still mapped in the East Breagh part of the structure, and initial planning is underway to drill and evaluate this part of the structure as part of a multiwell appraisal program in 2008.
"We are planning an active appraisal drilling program on the Breagh Block as well as further exploration drilling on the adjacent blocks," Gibson said. "In addition, a well on Block 210/29a is expected to be drilled in the first or second quarter of 2008."
Like the 42/13-3 well, all future wells will be designed to be retained for re-entry and possible production.
Contact Uchenna Izundu at [email protected].
