(596a) Dynamical Analysis of Sucker-Rod String In Artificial Lift Systems for Control Applications

The use of sucker-rod pumping systems continues to be the most common method of artificial lift in the oil-well industry. Although the basic design of the pump-jack systems utilized today remains based on centuries old principles, the advancements and implementation of modern equipment, materials, and control systems technology have all contributed to the improvement in well-site extraction efficiency and an overall increase in oil production from existing deposits, [4, 5]. One of the critical components of the pump-jack which has benefitted from the use of computer aided design is the sucker-rod string which connects the above ground mechanical lift system to the downhole pump apparatus, [7, 6]. However, the depth and underground well conditions prohibit the placement of sensory equipment, and together with the unavailability of output production measurements, prevent the collection of data which would enable the direct use of parametric modelling techniques. As a result, dynamic analysis of the sucker-rod is carried out using the available surface-card measurements of position and rod-load as inputs to a mathematical model with primary parameters of damping and rod elasticity to describe the overall rod-string behaviour at various well-depths, [1, 2, 3]. There exists a large amount literature on the subject matter and potential models of the rod-string behaviour have been proposed including systems of coupled ordinary differential equations and variations of the damped wave-equation. The primary focus of this work is the comparison of various models which are suitable for the purpose of controller design applications. The models must be reliable, sufficiently capture the rod-string dynamics, predict the downhole pump-behaviour, facilitate diagnostic and predictive well-analysis, and also allow for the design of low order controllers for practical implementations in individual well-sites and for further use in plant wide production optimization strategies.

References

[1] S.G. Gibbs. Predicting the behavior of sucker rod pumping systems. Journal of Petroleum Technology (July), pages 769–778, 1963.

[2] S.G. Gibbs. A general method for predicting rod pumping system performance. Society of Petroleum Engineers, 6850:9–12, 1977.

[3] S.G. Gibbs. A review of methods for design and analysis of rod pumping installation. Society of Petroleum Engineers, 9980:49–78, 1982.

[4] B. Guo, W.C. Lyons, and A. Ghalambor. Petroleum Production Engineering. Gulf Professional Publishing, 2007.

[5] S. Miska, A. Sharaki, and J. M. Rajtar. A simple model for computer-aided optimization and design of sucker-rod
pumping systems. Journal of Petroleum Science and Engineering, 17:303–312, 1997.

[6] Dawood Momeni, George V. Chilingarian, and Axelson W.B. Hatcher. An alternative approach tot he analysis of
sucker-rod dynamics in vertical and deviated wells. Developments in Petroleum Science, 19(1):531–634, 1987.

[7] G. Takacs. Sucker-rod pumping manual. PennWell, Tulsa, OK, U.S.A., 2002.