| A thorough review of the state-of-the-art in both diagnostic and design techniques is presented. A new approach based on the method of characteristics is proposed as an improvement over current diagnostic techniques that establish downhole conditions from polished rod measurements. This new approach is more flexible, allows the estimation of computational error, yields a more accurate downhole load estimation and compares very favorably with the state-of-the-art codes in a number of field cases studies.;Nicol's work in the design of pumping installations is extended. A discrete model, similar to the one investigated by Midwest Research but using the digital computer, is presented in order to study pumpoff, unanchored tubing and gas inteference downhole conditions.;A Downhole Instrumentation Unit, designed and built in cooperation with G.D. Albert, was used to obtain downhole measurements in a pumping well. The test results show that the diagnostic technique using the method of characteristics with a viscous damping term is in very good agreement. |
