Lessons Learned and Safety Considerations for Installation and Operation of a Managed Pressure Drilling System on Classed Floating Drilling Rigs

摘要

This paper will discuss the review, integration assessment, engineering analysis, and process safety analysis carried out prior to installing a managed pressure drilling (MPD) system on a classed floating mobile offshore drilling unit (MODU). MPD techniques have proven cost-effective, reliable, and safe when drilling difficult onshore wells, as well as drilling from MODUs with a surface blowout preventer (BOP). However, the implementation of MPD on deepwater wells has been hampered by industry inertia and questions about reliability, barriers, riser gas management (RGM), and general riser interface issues. This paper will focus on those distinctly different aspects introduced by MPD while drilling from a floating MODU. The primary objective will be to highlight how innovative application of MPD can enhance safety when drilling challenging wells in deep water. Additional insights are provided regarding experience from several MPD installations on deepwater rigs around the world that have been tasked with drilling challenging wells. The process employed in these discussions are mainly centered on the following major categories of MPD equipment and methods: ? Installing and operating a rotating control device (RCD) below the ocean's surface, including integration with a riser gas handling device. ? Redundancy and fail-safe considerations for valving, both for flow lines and control lines. ? Piping, umbilicals, and hoses in the moon pool area. ? Nodal safety assessment of the system. ? An Operator-Contractor-Service Company 'bridged' well control philosophy. The procedures will recount safety considerations of equipment classifications and system certification for MPD systems used on deepwater rigs. The lessons learned during this project help to establish a baseline for standardizing MPD drilling equipment and systems for global applications. The knowledge gained also was instrumental for the classification society certifying this equipment and system to develop safety and certification requirements aimed at improving MPD safety on deepwater drilling units. This paper will outline the core steps taken to achieve classification of an MPD system for a MODU, as well as enable increased utilization of MPD methods in deepwater wells worldwide. Class and certification can provide greater confidence to offshore operators that they can commission drilling equipment and systems capable of delivering safer, more dependable MPD wells, some of which may be considered un-drillable using conventional methods.