For the past 60 years, the dynagraph has been useful in measuring well performance and diagnosing trouble conditions downhole. More recently, surface dynagraph data, with other well-specific parameters, has served as input to mathematical models for predicting downhole behavior. Various computer programs exist to perform this task, and none have previously been verified empirically. In fact, no downhole force measurements have been made since 1942, by Lamberger and Langer (see Ref. 1).

An apparatus was developed, as a master's thesis project, to make these measurements. The device is a microcomputer-based data acquisition system that is wholly contained in a five-foot section of standard tubing. It was designed and built to mount in series with the sucker rod string, directly above the pump, and to sample and store real-time data of load, displacement, pressure, and temperature for analysis at the surface. This paper describes the unit, some of its development, and the results of the successful August 1986 field test, executed at over one mile of depth.

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