Control Requirements for Automatic Managed Pressure Drilling System

Abstract

Summary Automatic control solutions for drilling are expected to become widely used in the future. Both basic and more advanced control tools are well established in other communities such as offshore processing facilities and oil refineries. Drilling systems, however, have traditionally been operated manually. There is a great economic potential for the introduction of automatic control providing reduced drilling time, increased regularity, and improved performance, especially for wells with very narrow pressure margins. One example of automated drilling is automatic control of the downhole pressure by topside choking in managed-pressure-drilling (MPD) operations. Narrow drilling margins, especially in depleted reservoirs, ask for highly accurate pressure control. Statoil applied automatic MPD successfully offshore at the Kvitebjørn field in the North Sea in 2007. This paper presents some MPD results from Kvitebjøm and discusses automatic control requirements for drilling operations. The requirements for MPD operations include a specified accuracy for a set of normal operations, such as rate changes and set point ramping during connections, surge and swab, and some failure operations, such as power loss, gas kicks, and blocked choke. The paper also includes some ideas for the future of intelligent-drilling operations with increasing automation.

Design and Comparison of Constrained MPC With PID Controller for Heave Disturbance Attenuation in Offshore Managed Pressure Drilling Systems

“…The heave motion may be more than 3 meters in amplitude and typically has a period of 10-20 seconds, which causes severe pressure fluctuations at the bottom of the well. Pressure fluctuations have been observed to be an order of magnitude higher than the standard limits for pressure regulation accuracy in MPD (about ±2.5 bar) (Godhavn(2010)). Downward movement of the drill string into the well increases pressure (surging), and upward movement decreases pressure (swabbing).…”

Fault diagnosis of downhole drilling incidents using adaptive observers and statistical change detection

“…Here large drilling vessels are used, or the oil and gas platform is designed with drilling capabilities. An unwanted cost driver is non-productive time (NPT), which typically is between 20-25 % of drilling time [1]. One of the major contributors to non-productive time is unforeseen incidents happening with the equipment on the rig, or downhole in the well.…”

“…One of the major contributors to non-productive time is unforeseen incidents happening with the equipment on the rig, or downhole in the well. Early detection and isolation of an incident is of great importance [1], since early detection and mitigation can reduce the impact of an incident. Downhole incidents may in particular be challenging to detect, and to distinguish one type of incident from another may be even more difficult.…”

Early Pack-Off Diagnosis in Drilling Using an Adaptive Observer and Statistical Change Detection

“…One such improvement is wired pipe with pressure (and temperature) measurements along the drillstring, giving real-time data of the wellbore (Godhavn, 2010). This technology has been suggested as a tool for pack-off detection and localization in Long and Veeningen (2011).…”