The four-well program, conducted from the semisubmersible Transocean Arctic, should take around a year to complete.
Activity since April at the field, 259 km (161 mi) north of Kristiansund has included installation of pipelines and the subsea manifold at a water depth of 400 m (1,312 ft).
Four subsea wells will be tied back to Heidrun via a 15-km (9.3-mi) pipeline. From there, production will connect via a 7.5-km (4.67-mi) spur line to the Polarled gas transportation system, finally landing ashore to undergo further processing to dry gas at the Nyhamna terminal.