CHEVRON is drilling a third appraisal well in the Rosebank area west of Shetlands, and expects the programme will be finished in the next two months. The US oil major is using the Transocean Rather semi-submersible rig on well 213/27-A2 in the northern part of the structure.“It is expected that the programme will be completed by November, when analysis of the appraisal data will determine the future work programme for the discovery,” said a Chevron spokeswoman in Aberdeen.The same rig drilled a second appraisal well into Rosebank in the summer. This encountered 80 ft of vertical oil pay and was tested at 6,000 barrels per day. The 205/1-1 well was drilled in 3,700 ft of water on the southern end of Rosebank.“This is a very encouraging result in a difficult environment and increases our confidence in the scale and feasibility of this exciting prospect,” said Chevron managing director Rick Cohagan. “We are gathering good data that will help us determin