“The Colter well (98/11a-6) has been drilled as a vertical well with the Ensco-72 jack-up rig and has reached a Total Depth of 1,870m MD in the Sherwood Sandstone. The well is an appraisal of the 98/11-3 well, drilled in 1986 by British Gas, within the Colter Prospect.
“The 98/11a-6 well unexpectedly remained on the southern side of the Colter Prospect bounding fault but encountered oil and gas shows over a 9.4m interval at the top of the Sherwood Sandstone reservoir. A petrophysical evaluation of the logging while drilling data has calculated a net pay of 3m. Similar indications of oil and gas were encountered in the 98/11-1 well, drilled in 1983 by British Gas, within the Colter South fault terrace. Provisional analysis of the new data indicates that the two wells may a share a common oil-water-contact, having both intersected the down-dip margin of the Colter South Prospect. Corallian’s most recent assessment of the Colter South Prospect prior to drilling the 98/11a-6 well had estimated a mean recoverable volume of 15 mmbbls. Further work will be required to refine this assessment with the new well data.
“The joint venture has commenced preparations to side-track the 98/11a-6 well. The side-track will be drilled directionally to a Sherwood Sandstone target within the Colter Prospect on the northern side of the bounding fault, and will take approximately 2 weeks to complete.
“It is encouraging that the well has confirmed a discovery in the Colter South Prospect. More work will be required to determine the resource potential within the structure and we look forward to the results of the side-track to evaluate the Colter Prospect.”