With US shale drilling costs rising, especially in the red-hot Permian, a return to offshore exploration and development is looking more attractive – but only if costs can be held down.

The US onshore rigcount, at 954, is well over double the May 2016 low. Mideast drilling never really dipped (see table and MEES, 14 July). But offshore drilling so far shows little sign of budging from record lows. Numbers from services firm Baker Hughes indicate a global offshore rig count of 230 for...