Abstract: As a big typical offshore heavy oil block in Bohai field, S oilfield has entered into a middle-late period of oilfield development and gradually exposed many problems such as injection-production serious contradictions, big producing difference of interlayer and on the plane, single well high probable reserves, low oil producing rate and low recovery. Aming at the development challenges, a large-scale comprehensive adjustment of offshore oilfield has been proposed in this paper, with an emphasis on open degree research of adjustment wells. From shooting into water flooded layers to appropriately avoid shot in interlayers and interior layers, and to strictly avoid shot in potential water flooded layers, the reasonable open degree principles of adjustment wells in high water-cut stage have been finally established. According to the reasonable open degree principles, the implementation of the follow-up adjustment wells has been carried out, therefore, oil production increase and water production control have been effectively achieved.