L1 adaptive control has attracted StatOil and Schlumberger for possible applications in managed pressure drilling and rotary steerable systems.

Managed Pressure Drilling (MPD)

Joint work with Statoil Research Center, Porsgrunn, Norway

Managed pressure drilling is a technology to control the bottom hole pressure precisely. Compared to traditional (over-balanced or under-balanced) drilling processes, MPD provides less non-productive-time, less fluid loss and gas/oil influx, more efficiency and productivity, higher level of safety and can be used to drill otherwise undrillable wells.

The basic principle of MPD is to seal the annulus top and use the chock opening plus an additional back-pressure to control the bottom hole pressure and compensate for annular pressure fluctuations. The objective is to precisely control the bottom pressure to a given value which is between some safety margin, which is very narrow especially for deep water or mature wells.

The main challenges of the problems are due to the uncertainties of the system, both the unmeasured states and uncertain dynamics. On the one hand, the measurement from the bottom hole (flow rate and pressure, etc.), if possible, are transmitted by telemetry and updated at a low rate. For the purpose of control, these bottom hole variables need to be estimated in real-time. Another challenge is the uncertainty in the model for the bottom hole, due to uncertainties in the friction, density and mud compressibility parameters as well as the unmodeled dynamics in the actuator.

These challenges motivate the design of an integrated estimation and adaptive control scheme. We first design an estimator to provide real-time estimation of the bottom hole pressure and flow rate. Then we design an L1 adaptive controller which compensates the uncertain parameters and unmodeled dynamics, using the estimated pressure and flow rate from the estimator. The main contribution of this work is that we provide an integrated estimation and control scheme, instead of just pressure estimation or just control, done in some previous work. Moreover, since the system is nonlinear, the certainty equivalence argument does not apply. Thus, we provide analytic proof of the stability and performance of the integrated estimation and control scheme.

Publications

  • H. Mahdianfar, N. Hovakimyan, A. Pavlov, and O. M. Aamo, L1 Adaptive Output Regulator Design with Application to Managed Pressure Drilling, in Journal of Process Control, vol. 42, pp. 1-13, 2016.
  • Z. Li, N. Hovakimyan, and G.-O. Kaasa, Bottom hole pressure estimation and L1 adaptive control in managed pressure drilling system, in International Journal of Adaptive Control and Signal Processing, Vol. 31, pp. 545–561, 2016.
  • H. Sun, Z. Li, N. Hovakimyan, T. Basar, and G. Downton, L1 Adaptive Control for Directional Drilling Systems, in Proceedings of 1st IFAC Workshop on Automatic Control of Offshore Oil and Gas Production, Trondheim, Norway, pp. 72-77, 2012.
  • Z. Li, N. Hovakimyan, and G.-O. Kaasa, Bottomhole Pressure Estimation and L1 Adaptive Control in Managed Pressure Drilling System, in Proceedings of 1st IFAC Workshop on Automatic Control of Offshore Oil and Gas Production, Trondheim, Norway, pp. 128-133, 2012.
  • Z. Li, N. Hovakimyan, G.-O. Kaasa, Fast Estimation and Adaptive Control for Bottomhole Pressure in Managed Pressure Drilling, in Proceedings of IEEE Multi-Conference on Systems and Control, pp. 996-1001, Denver, CO, 2011.
  • Z. Li, N. Hovakimyan, C. Cao and G.-O. Kaasa, Integrated Estimator and Adaptive Controller for Well Drilling, in Proceedings of American Control Conference, St. Louis, MO, pp. 1958 – 1963, 2009.

 

Contact:

Naira Hovakimyan
Zhiyuan Li
Glenn-Ole Kaasa		 nhovakim (at) illinois (dot) edu
li64 (at) illinois (dot) edu
gkaa (at) statoil (dot) com

Rotary Steerable System