This book reports the results of exhaustive research work on modeling
and control of vertical oil well drilling systems. It is focused on the
analysis of the system-dynamic response and the elimination of the most
damaging drill string vibration modes affecting overall perforation
performance: stick-slip (torsional vibration) and bit-bounce (axial
vibration). The text is organized in three parts.
The first part, Modeling, presents lumped- and distributed-parameter
models that allow the dynamic behavior of the drill string to be
characterized; a comprehensive mathematical model taking into account
mechanical and electric components of the overall drilling system is
also provided. The distributed nature of the system is accommodated by
considering a system of wave equations subject to nonlinear boundary
conditions; this model is transformed into a pair of neutral-type
time-delay equations which can overcome the complexity involved in the
analysis and simulation of the partial differential equation model.
The second part, Analysis, is devoted to the study of the response of
the system described by the time-delay model; important properties
useful for analyzing system stability are investigated and frequency-
and time-domain techniques are reviewed.
Part III, Control, concerns the design of stabilizing control laws aimed
at eliminating undesirable drilling vibrations; diverse control
techniques based on infinite--dimensional system representations are
designed and evaluated. The control proposals are shown to be effective
in suppressing stick-slip and bit-bounce so that a considerable
improvement of the overall drilling performance can be achieved.
This self-contained book provides operational guidelines to avoid
drilling vibrations. Furthermore, since the modeling and control
techniques presented here can be generalized to treat diverse
engineering problems, it constitutes a useful resource to researchers
working on control and its engineering application in oil well drilling.
