Abstract—In the present work an algorithm is proposed for automatic guidance of bit in directional drilling process. In the manual mode control of bit’s movement some problems arise due to operational and human inaccuracies which make the actual path differ from the desired one. In this article an automatic control system based on the bang-bang control strategy equipped with MWD (Measuring While Drilling) has been designed to lead the bit to the target. The bang-bang control strategy is one of the optimal nonlinear control methods. According to the kinematic constraints and system’s input variables of the present problem this control strategy is suitable and simple to implement. In the first step the kinematic model of the drillstring movement has been derived. In the second step using Matlab-Simulink software, the system’s kinematic equations besides some effects such as mechanical behavior of the well, dead zone between the formation and the bit, changing the geological formation during the drilling, time delay in sending and receiving mechanical and electrical signals, and environmental noises have been taken into account and are modeled. Directional drilling has been simulated with empirical parameter values of the well formation in Nargesi field. To study the control system abilities and limitations, results were obtained and studied. It is shown that the control system can generate an appropriate path when the result is compared with an actual drilling data. In the final part the concluding remarks are presented.
Index Terms—MWD, bang-bang control, directional drilling, drillstring well interaction.
Amir Rouzgard is with the Islamic Azad University: Branch Ahvaz,
Ahvaz, Iran, (corresponding author to provide phone: +989128157841;
fax:+986314434558; e-mail: a.roozgard@gmail.com).
Kourosh Heidari Shirazi is with the Shahid Chamran University, Ahvaz,
Iran. (e-mail: k.shirazi@scu.ac.ir).
Cite: Amir Rouzgard and Kourosh Heidari Shirazi, "Optimal Nonlinear Control in MWD assisted Directional Drilling Process," International Journal of Modeling and Optimization vol. 1, no. 4, pp. 302-306, 2011.
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