Abstract

With increasing utilization of Managed Pressure Drilling (MPD), the industry today is leaning heavily towards the use of improved safety aspects that MPD systems exhibit. With the technological advancements to detect influxes, some of today's MPD systems are equipped with algorithms to automatically apply surface backpressure (SBP) in order to restore the overbalance while retaining the ability to circulate the small volumes of formation fluids (influx) that entered the wellbore prior to achieving the overbalance. Even when conventional well control (shutting well on BOP and circulating the kick out conventionally with the rig's choke) is used, the effectiveness of circulating a small influx using the automated MPD choke is a significant advancement for the drilling industry overall.

Some MPD systems used today have the capacity to prevent shut-in scenarios by automating the influx- handling process. The influx management envelope (IME) or MPD matrix traditionally defines the limits within which the MPD system could potentially be safely used to control and circulate these small influxes. This paper primarily proposes advancing the methodology to define the shape and size of the MPD IME defined in SPE 170684 (Mehdi 2014). It explains the changes in the shape of the IME using appropriate examples, for the various limiting factors, such as, "shoe strengths lower than RCD (Rotating Control Device) limit," "shut in scenario during circulating influx," "maximum flow rate for circulation," "mud compressibility with added backpressure," "Mud gas separator (MGS) liquid and gas handling capacity" etc. The modified shape of the resulting MPD IME is discussed systematically in this paper.

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