Technology Update: Retrofitting MPD Systems to Deepwater Rigs Aids Drilling, Efficiency, and Process Safety

Abstract

The unique properties of deepwater formations pose significant challenges to the capabilities of conventional drilling rigs. By retrofitting rigs with automated drilling systems, including managed-pressure drilling (MPD) equipment, operators and contractors in global deepwater basins can optimize efficiency and economics while maintaining the level of safety that the industry and regulatory community have mandated for this high-stakes arena.

MPD, an adaptive drilling process that actively controls annular pressure throughout the wellbore, is increasingly being integrated into the risers of existing deepwater drilling vessels (Fig.  1). It is the cornerstone of an automated well-control strategy that augments and enhances standard well-control protocols.

The technique provides distinct drillability, efficiency, and process safety benefits in deepwater environments. It addresses the higher level of priority that the industry has placed on process safety, which largely involves the ability to accurately and actively monitor and control operations while drilling. 

Long used in land and shallow-water drilling, MPD-ready rigs are proving their value in deepwater operations by delivering a reliable level of automation and process control when the risk of a well-control incident is highest. Fluctuations in wellbore pressure often create drilling hazards that result in lost circulation, kicks, and other problems that can significantly increase rig time and cost, or lead to catastrophic well-control incidents.

An automated MPD system installed onto a deepwater semisubmersible rig or drillship can effectively monitor and maintain the annular hydraulic pressure profile by applying common MPD variants, such as constant bottomhole pressure (CBHP) and pressurized mud cap drilling (PMCD).

The ability to continuously monitor various wellbore parameters—particularly those related to downhole pressure—while drilling and making connections also enhances personnel preparedness by serving as an extra set of eyes to supplement those of less-experienced drillers.

While expanding the drilling envelope and monitoring wellbore pressure profiles, an MPD system that provides automated advanced flow detection, including early kick detection, also reduces the risks of human intervention by mitigating the possibility of gas in the riser.