From Influx Management to Well Control; Revisiting the MPD Operations Matrix

Abstract

Managed Pressures Drilling (MPD) offers the capability to detect very small influxes when compared to using conventional rig equipment. Furthermore, the potential exists to control and circulate out the influx with the MPD equipment, without shutting in and performing conventional well control. When executed appropriately, this approach to managing an influx represents a higher degree of safety and enormous cost savings. However, managing an influx with MPD, particularly when a subsea BOP is in place, is quite different to conventional well control. A critical part of implementing MPD is to ensure that there is a clearly defined procedure for determining when MPD influx management must cease, and well control be initiated. A typical approach, regulated in some regions and voluntarily followed in others, is to create an MPD Operations Matrix before the operation begins, which outlines procedures that should be followed based on identifiable parameters following an influx. This matrix clearly identifies when it is appropriate to carry on with normal MPD operations, perform specific MPD influx control strategies, or shift to conventional well control. Forming the MPD Operations Matrix, however, can be challenging and has frequently been created inappropriately for the situations in which its use is intended. Development of a good understanding of how the well pressures and flow rates behave during MPD influx management is critical to ensuring a seamless handover between MPD influx management and Well Control. In this work, extensive transient multiphase simulation is used to demonstrate the sensitivity of surface pressures to well, drilling and influx characteristics and their resulting importance in the development of an operations protocol. Particular attention is given to influx volume, intensity and dispersion within a water based drilling fluid. Also considered are multiple wellbore geometries with primary focus on deepwater applications, oil based drilling fluid, pump rate and drilling fluid density and rheology. Where possible, findings are validated using recorded field data. This paper discusses and defines the transition between MPD influx management and conventional well control. The key parameters for calculating the boundaries of MPD influx management are determined and a protocol developed for smooth handover to well control operations. The protocol enables guidance to varying levels of influx management ranging from full influx detection and removal using the MPD equipment, to assisted shut in.

MPD Dynamic Influx Control Mitigates Conventional Well Control Pitfalls

“…Secondly, by circulating the influx out through the MPD equipment, the larger diameter of the riser means that less hydrostatic pressure is lost than if the gas must travel through the low ID choke and kill lines. This significantly reduces the peak pressures seen at surface as was demonstrated in (Bacon, et al, 2015). • Pressure While Drilling (PWD) information can be maintained throughout the circulation process, giving an extra level of BHP control.…”

“…Clearly identifying when an influx is beyond the capacity of the primary barrier and how to execute a safe handover to the secondary barrier system is critical to safe and efficient implementation. A key document for capturing these procedures is the MPD operations matrix discussed extensively in (Bacon, et al, 2015).…”

“…Simulations performed with this method have provided results consistent with field data (Hollman, et al, 2015) and, therefore, provide a reasonable level of confidence when used to compare methods for controlling influx. Previous work (Bacon, et al, 2015), where this method of simulating MPD dynamic influx control was first presented, contains details regarding some of the methods used and typical results obtained.…”

MPD Technology Used to Deliver Challenging HPHT Drilling Campaign

“…Understanding the MPD Operating Matrix (Bacon et al 2015) is critical to ensuring well control is not compromised by introducing a new technology and associated interfaces. In general, the well control philosophy used identifies that MPD can be used only for influxes that would typically be considered below the normally accepted resolution of the rig's kick detection system.…”