Use of Managed-Pressure Drilling Requires Adjustments To Bridge Gap to Well Control
Authors: Wilson Adam 
Published: December 2017

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper IADC/SPE 178810, “Bridging the Gap Between MPD and Well Control,” by Thiago Pinheiro da Silva, Landon Hollman, SPE, Gustavo Puerto Corredor, and Patrick Brand, SPE, Blade Energy Partners, prepared for the 2016 IADC/SPE Drilling Conference and Exhibition, Fort Worth, Texas, USA, 1–3 March. The paper has not been peer reviewed.
Managed-pressure drilling (MPD) challenges the conventional drilling paradigm, along with drilling-contractor and operator policies and standards. Conventional drilling practices for connections, flow checks, tripping, and well control have been long understood and standardized both onshore and offshore. The addition of an MPD system to a drilling operation, inclusive of the recommended practices, requires bridging the gap between conventional policies and standards and those of MPD.
Introduction
Often, an MPD bridging document that supplements the standard drilling-contractor and operator bridging document is seen as an operational requirement. The drilling contractor remains responsible for well control and well monitoring. The driller will continue to monitor the well at all times, using standard operating procedures while observing key drilling parameters.
The MPD system provides enhanced well-control-event-detection methods in addition to standard downhole-event-detection methods. In addition, it allows rapid and accurate control of bottomhole pressure (BHP), but it does not replace standard drilling-contractor or operator procedures during well-control events.
Depending on the MPD-system avail-ability and capabilities and the actual well conditions, most operators use several MPD techniques on the same well. The techniques may include conventional drilling with riser-gas-handling capabilities, dual-gradient dynamic-mud-cap drilling, pressurized-mud-cap drilling, floating-mud-cap drilling, or applied-surface-backpressure MPD. All of these fall into the group of techniques now referred to in the industry as MPD.
Depending on the technique used, the mud density might be statically overbalanced, meaning that the hydrostatic pressure alone exceeds the highest formation pore pressure exposed, or it might be statically underbalanced, meaning that hydrostatic pressure alone may be less than the highest formation pore pressure exposed and the well is kept overbalanced by applying backpressure at surface.
Well-established corporate policies have guided conventional drilling practices with respect to operational issues such as kick-indicator response, frequency of equipment testing, fingerprinting, and proactive kick-minimization techniques. Although MPD serves the same purpose as conventional drilling—to drill a section safely overbalanced—its use requires procedures that deviate from established policies.
Barriers
Conventional Drilling. For conventional drilling techniques, a minimum of two independent and tested barriers must be in place at all times. Upon failure of a barrier, normal operations must cease and not resume until a two-barrier position has been restored.