J. Douglas Wilkerson, Texas Tech University
One purpose of obtaining a surface dynamometer card is to learn how well the downhole pump is functioning. Several methods have been used to develop a finite mathematical model of a simplified pumping system to predict or evaluate pump behavior given dynamometer polished rod loads and displacement at the surface. The purpose of these methods was to develop a computerized method of analyzing surface dynamometer cards. The alternative is to evaluate the card by visual inspection, which is very subjective, requires a skilled analyst, and yields results which are strictly qualitative in nature. The work done by Gibbs, in particular, has apparently been successful, considering the expense involved in using or obtaining one of his patented programs.' Otler than the expense, the programs are generally designed for applications with main frame computers, and the development of the equations used in the programs seems to have been left purposefully ambiguous. The purpose of this paper is to present a relatively comprehensive and user-friendly program for use with micro-computers based on a finite difference method initially developed by Roy Knapp at the University of Kansas.