Multi-objective evaluation model of 1-N positioning for offshore exploration wells

Due to the concentrated exploration deployment, the density of exploration wells in Bohai Oilfield is high, so drilling ships are required to perform short-distance towing many times between wells.However, the towing of offshore drilling platforms has special requirements on weather and ocean currents, and its relevant procedures are complicated, so the situations of long-time stand by often occur in the process of towing operation.In order to deal with high risks, high operation costs and low operation efficiency of multiple towing operations of drilling ships for the operations of exploration wells in Bohai Oilfield, a drilling mode of multi-objective evaluation within once in position (1-N drilling mode) for offshore exploration wells was explored based on the mature drilling technologies currently used in development wells and adjustment wells, e.g.window cutting, open hole sidetracking and borehole trajectory control.Then it was put into practice.In addition, the increased operation difficulties and cost to drill multilateral wells according to the 1-N drilling mode was estimated.Owing to the application of 1-N drilling mode Lvda and Penglai Blocks, single operating cost is saved by 20 million yuan and 15 million yuan, respectively, indicating the promising application prospect.The research results can be used as the reference for the similar exploration projects of offshore oilfields at home and abroad.