Control Requirements for High-End Automatic MPD Operations

Abstract

Abstract 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 like 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. StatoilHydro applied automatic MPD operations successfully offshore at the Kvitebjørn field in the North Sea in 2007, and several new MPD projects are currently being prepared. This paper presents some results from Kvitebjørn and discusses automatic control requirements for drilling operations. These requirements 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. Nomenclature APC = Advanced Process Control BHA = Bottom Hole Assembly CCS = Continuous Circulation System DCSS = Distributed Control and Safety System FPWD = Formation Pressure While Drilling GUI = Graphical User Interface HP = High Pressure HPHT = High Pressure High Temperature HSE = Health, Safety and Environment IMS = Information Management System KF = Kalman Filter MPC = Model Predicitive Control MPD = Managed Pressure Drilling MWD = Measurements While Drilling NPT = Non-Productive Time OPC = OLE for Process Control PID = Proportional, Integral and Derivative PWD = Pressure While Drilling RPM = Rotations Per Minute SG = Specific Gravity SPM = Strokes Per Minute TVD = True Vertical Depth