Innovative solutions to improve performances of drilling and completion operatons in ultra deepwater wells

Approximately one third of the global oil production comes from the offshore industry, and ultra deepwater wells are becoming more important to meet the demand. In this scenario, the request of high-performance offshore drilling rigs is rising, as the market moves towards deeper waters. However, due to the high day rates of top-notch drilling vessels, some oil companies are currently researching innovative solutions to improve performances of drilling and completion operations in ultra deepwater wells. After almost two decades of attempts, none of the technologies developed to upgrade existing rigs and increase their maximum drilling water depths has been considered promising by the industry, until now. In this work, two different approaches are extensively described and analysed: the reduction in riser size, which is the reduction in diameter of the riser main pipe, and the replacement of steel auxiliary lines with carbon fiber-reinforced polymer pipes, better known as composite pipes. Therefore, ten non-conventional marine drilling risers are designed through a simplified finite element model of the riser string, solved with the help of ANSYS Mechanical software. Finally, newly designed slim risers, hybrid risers and slim hybrid risers are compared with conventional marine drilling risers in order to assess benefits and consequences of field implementation for the mentioned innovative solutions.