The use of dynamically positioned (DP) rigs in Campos Basin, offshore Brazil, started in 1984 with an exploratory drilling program. Very soon it was confirmed that the many advantages of such vessels, if compared to conventionally moored rigs, surpassed any other problem associated with them. Therefefore, a milestone mark of over 20,000 days of operations ith DP rigs has been achieved not only in exporatory drilling and appraisal wells, but also for completions and workovers. As most of deep water developments, Campos Basin development is based on subsea completions and floating production systems hence the use of DP rigs is of utmost importance for the economical feasibility of such projects. As a consequence, their extensive use in such activities required the development of proper guidelineless (GLL) subsea hardwater systems. Moreover, amny workovers were also performed in guideline (GL) systems in shallow water which confirm the versatility of DP vessels chiefly due to their fastness to move between locations. In addition, several different DP rigs concepts and characteristics have been involved in these tasks that have allowed an evaluation and comparison of their performance. As a result, the performance in station keeping, in terms of lost time (DP problems themselves and evnrionmental conditions), between drillships and semi-submersibles and among different classes of drillships for different operations, such as drilling, completion unitil tubing hander installation, and installing wet christmas three will be presented in this paper, thus allowing the best allocation of the available working fleelt.
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