A previous attempt to drill an exploration well in ultra-deepwater in the Gulf of Mexico (GoM) did not reach its objective due to an inability to maintain a Water Based Mud (WBM) system light enough to maintain circulation. For the next round of exploration drilling, a system was sought that allows dynamic management of Equivalent Circulation Density (ECD). Conventional Rotating Control Device (RCD) based Constant Bottom Hole Pressure (CBHP) management systems were not suitable, as no drilling fluid light enough to manage ECD via backpressure could be applied for this campaign.

AGR has developed a pumped riser Managed Pressure Drilling (MPD) system named EC-Drill that facilitates an automated control of mud level inside the riser to a specific BHP set point to mitigate the problems of tight drilling margins in deep waters and low pressure reservoir. This allowed drilling from a semisubmersible with an adjustable mud level, effectively reducing BHP and managing ECD without using any types of backpressure devices. Fluid level inside the riser is adjusted by a field proven subsea pump system.

EC-Drill detects influxes and fluid losses quickly, allowing the driller to respond before significant problem occurs.

In this paper we will discuss how EC-Drill is planned to pave the way for the operator to access a previously unattainable ultra deepwater target. EC-Drill principles, well design, equipment, and planning will be covered.

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