Model-Based Robust Control of Directional Drilling Systems (original) (raw)
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Robust output‐feedback control of 3D directional drilling systems
International Journal of Robust and Nonlinear Control, 2018
SummaryThis paper introduces a robust observer‐based output feedback control strategy that enables the generation of complex three‐dimensional borehole trajectories created by directional drilling systems, while avoiding undesired transient behavior. The model‐based controller relies on a set of nonlinear delay differential equations describing the borehole evolution. Herein, only local orientation measurements of the bottom hole assembly of the drilling system are employed. Controller and observer gains are synthesized by optimizing the location of the rightmost pole of the closed‐loop dynamics, using a spectral approach for delay differential equations. Moreover, the strategy is extended to cope with the uncertainty of key system parameters in the directional drilling process. The effectiveness of the designed controller is tested in an illustrative benchmark study.
Tracking Control for Directional Drilling Systems Using Robust Feedback Model Predictive Control
IFAC-PapersOnLine
A rotary steerable system (RSS) is a drilling technology which has been extensively studied and used for over the last 20 years in hydrocarbon exploration and it is expected to drill complex curved borehole trajectories. RSSs are commonly treated as dynamic robotic actuator systems, driven by a reference signal and typically controlled by using a feedback loop control law. However, due to spatial delays, parametric uncertainties and the presence of disturbances in such an unpredictable working environment, designing such control laws is not a straightforward process. Furthermore, due to their inherent delayed feedback, described by delay differential equations (DDE), directional drilling systems have the potential to become unstable given the requisite conditions. This paper proposes a Robust Model Predictive Control (RMPC) scheme for industrial directional drilling, which incorporates a simplified model described by ordinary differential equations (ODE), taking into account disturbances and system uncertainties which arise from design approximations within the formulation of RMPC. The stability and computational efficiency of the scheme are improved by a state feedback strategy computed offline using Robust Positive Invariant (RPI) sets control approach and model reduction techniques. A crucial advantage of the proposed control scheme is that it computes an optimal control input considering physical and designer constraints. The control strategy is applied in an industrial directional drilling configuration represented by a DDE model and its performance is illustrated by simulations.
Adaptive Control for Directional Drilling Systems
2012
This paper considers downhole directional drilling systems in the presence of unexpected variations in steering force, input delays, measurement noise and measurement delays, and explores the application of L1 adaptive controller for the trajectory control problem. The Explicit Force, Finitely Sharp, Zero Mass (EFFSZM) model is used for the steering system, in which spatial delays, modeling inaccuracies, parametric uncertainties, and noise are considered. The L1 adaptive controller ensures that the centerline of the borehole follows a well path planned according to a priori available geologic conditions and local residential information. Path tracking results are demonstrated by simulations.
Challenges of Modeling Drilling Systems for the Purposes of Automation and Control
2012 IFAC Workshop on Automatic Control in Offshore Oil and Gas Production, 2012
To fully model every aspect of the process of drilling a borehole is still in the realms of research. Great strides are being made to develop high-fidelity models of well-defined domains such as the rig systems, drillstring, rock-bit interaction, fluid control systems and the Earth. Bringing all these models together in any unified manner and proposing a unified control solution to fully automate the whole process is still an exploratory venture. The uncertainty prevailing over the magnitude and spatiotemporal distribution of disturbances to be controlled or rejected by systems best described by non-linear partial differential equations rather than linear approximations, makes for a very challenging control problem. This uncertainty also raises interesting questions on how detailed the models need to be and how this might change our approach to modeling in the future. However technology is never static and certain developments are currently in play that will dramatically improve our capacity to model and control processes which are currently considered too complex to control.
Design and analysis of robust controllers for directional drilling tools
2016
Directional drilling is a very important tool for the development of oil and gas deposits. Attitude control which enables directional drilling for the efficient placement of the directional drilling tools in petroleum producing zones is reviewed along with the various engineering requirements or constraints. This thesis explores a multivariable attitude governing plant model as formulated in Panchal et al. (2010) which is used for developing robust control techniques. An inherent input and measurement delay which accounts for the plant’s dead-time is included in the design of the controllers. A Smith Predictor controller is developed for reducing the effect of this dead-time. The developed controllers are compared for performance and robustness using structured singular value analysis and also for their performance indicated by the transient response of the closed loop models. Results for the transient non-linear simulation of the proposed controllers are also presented. The results...
Drilling seeking automatic control solutions
Proc. 18th IFAC World …, 2011
This paper addresses control challenges within drilling for the oil and gas industry. Drilling has not been modernized as much as other industries and there is still a great potential for automatic control. Heavy machinery is used to handle pipes and other equipment topside and in and out of the hole. These machines can be controlled remotely with a joystick. Very advanced tools are being used downhole several km away from the rig and these are often controlled remotely. Mud pulse telemetry with low bandwidth is used to communicate with downhole equipment. Drilling involves certain risks and mistakes may have disastrous consequences both for people and economically, e.g. a blow-out. Safety is therefore always the most important issue, and new solutions must be robust and fault tolerant. Extensive testing is required before being used in an actual drilling operation. Managed pressure drilling is a relative new method for drilling challenging wells with narrow margins requiring precise pressure control. Nonlinear model based control solutions and observers have been developed for this technology. This is addressed in this paper together with experimental results. In addition an overview of some other interesting challenges is given.
The Modelling and Control of a Deep Hole Drilling Rig
IFAC Proceedings Volumes, 1995
Drill bit performance in terms of average penetration rate and life has become extremely important because time dependant costs have become the major proportion of the total costs per meter drilled, due to the deep holes encountered, especially in the gold exploration drilling industry. This paper gives an overview of the important parameters influencing the drill bit performance. An instrumentation and control system has been implemented for controlling these parameters. An analysis and simulation done on an assumed model indicated that stable, well damped, closed loop control could be maintained over the wide range of system dynamics which were expected to be encountered in the system. Practical observational results agree well with the results obtained by the simulation.
The Journal of Engineering, 2019
A directional drilling tool control unit whose design is based on servo control of a rotary valve using the roll-stabilised instrumented system approach has been successfully used in oil fields for over 20 years. Here, field-oriented control (FOC) is applied to cascaded voltage regulation and servo control using an open-loop plant model of the roll-stabilised control unit. The servo control is applied to the rotary valve so that drilling mud is ported in a geostationary direction despite the rotation of the drill string and the bottom hole assembly of the rotary steerable system. Voltage regulation is applied in order to provide a DC voltage bus for the servo control of the valve. A torquer or alternator, which is a type of permanent magnet synchronous machine, is the core of the roll stabilised control unit. So, a mathematical model of the torquer is derived. An FOC scheme is proposed for servo control and to provide a DC regulated voltage using the torquers. The algorithm is tested in MATLAB/ Simulink.