LONDON – Independent Oil and Gas plc (IOG) has provided initial results from its first operated appraisal well on the Skipper heavy-oil discovery in block 9/21a in license P1609 in the UK northern North Sea.
The Skipper appraisal well was successfully drilled to a total vertical depth of 5,578 ft (1,700 m) in August. The crest of the reservoir was found to be 44 ft (13 m) shallower than originally anticipated. As a result, management’s estimate of the most likely oil in place has increased from 136.5 MMbbl in the 2013 Competent Persons Report to 142.6 MMbbl. An increased distance between the crest of the reservoir and the oil/water contact in any development will improve the likely oil recovery by delaying the onset of water breakthrough.
The quality of the sands, although not cored, suggested permeabilities in excess of 10 Darcies, which is significantly better than previously assumed.
Although the oil is moving in the reservoir, the first sample results indicate that the oil is around 11° API and has a significantly higher viscosity than expected.
These measurements do not align with IOG’S observations and therefore the remaining samples need to be reviewed and tested. Next steps will then be reservoir modeling to consider potential development options. Determining commerciality may therefore take several months
The initial license commitment on P1609, to drill a well into the Maureen formation to a minimum depth of 1,700 m (5,578 ft) has now been fulfilled and the license will now proceed into the second term.
Mark Routh, CEO of IOG, commented: “The analysis of the oil retrieved from the appraisal well indicates that Skipper is a heavy-oil discovery with similar gravity to other nearby heavy oil fields. We have observed that the oil moves in the reservoir and is mobile at surface at ambient conditions.
“The initial oil analysis results are incompatible with our observations, therefore we are now reviewing our strategy to establish the commerciality of Skipper. In addition, we have an increased oil in place, higher observed reservoir permeabilities, and an increased reservoir height from the crest to the oil/water contact.”