North Sea-focused explorer Antrim Energy jumped on Thursday after two pieces of news got investors excited.The firm said Premier Oil had begun drilling operations at the Cyclone prospect in the Central North Sea, in which Antrim has a 30% working interest.The drilling will target the Tertiary Cromarty sandstones at a drilling depth of approximately 5,000 feet true vertical depth.Antrim also announced the UK government had approved its field development plan for the Cormorant East Field.The plans calls for the field to be initially produced under primary depletion, with the potential to install awater injection scheme at a later date.Shares in Antrim were up 9.8% at midday on Thursday following the announcements.