North Falkland Basin oil explorer Rockhopper started drilling the 14/10-4 appraisal well at the weekend.It's the first appraisal well to be drilled on the Sea Lion feature on the 100% owned and operated Licence PL032.The well is 2.3km from the Sea Lion 14/10-2 discovery well, found last September to be commercially viable. Rockhopper will take about 38 days to drill down around 3,000 metres to investigate the possibility of deeper sands than those encountered in the Sea Lion discovery well.