Given the high day rates of deepwater drilling and workover rigs, the overall drilling and well maintenance costs for subsea wells are a significant part of the total costs for deepwater field developments.
Recent drilling and completion technologies have resulted in improved reliability, higher production levels and an increase in recovery for individual wells. This has allowed for an optimization of the well system design and total well count in deepwater areas. A cost-effective access to the well and regular well maintenance during the field life are considered key issues for optimal reservoir management, which allows for accelerated production, an increase in Ultimate Recoverable Reserves (URR)and significant savings in operating costs during the field life (e.g.optimal design of process facilities).
A Floating Production and W orkover Unit (FPW U), allowing for simultaneous production and workover operations from a large monohull floater, without the need for an additional well intervention vessel has been developed (Figure 1).