A significant number of the largest oil fields in Russia are at a late stage of development. Operation of low-flow wells is carried out mainly by sucker-rod pump units. Timely diagnostics of the technical condition and operating conditions of pumping equipment is an important condition for ensuring cost-effective well development. The article considers a new approach to the diagnosis of sucker-rod pump units based on mathematical modeling of their operation and the construction of theoretical dynamometer cards. By varying the parameters characterizing the complicating factors, the configurations of dynamometer cards during the operation of pumping equipment under various conditions (leaks in the discharge and receiving parts of the pump, high and low fit of the plunger in the cylinder) are analyzed. It has been found that leaks through the pump valves have a significant impact on the configuration of the load and discharge lines of the pumping rods on the dynamometer cards, and with an increase in volumetric supply losses due to leaks in the discharge valve, the length of the load perception line increases. An increase in supply losses due to leaks in the suction valve leads to an increase in the length of the rod discharge line. It is shown that the estimation of the volume of leaks through the pump valves according to the dynamometer cards makes it possible to make an informed decision on optimizing the operation mode of the well, conducting underground repairs. The configuration of dynamometer cards at a high landing with the plunger exiting the pump cylinder, the plunger hitting the suction valve cage at the end of the downward stroke at a low landing is analyzed. It is shown that the construction of theoretical dynamometer cards and their comparison with the actual one makes it possible to calculate the stroke length of the polished rod, accompanied by the output of the plunger from the cylinder (the impact of the plunger on the suction valve cage). For the considered examples, the principles of solving the problems of quantitative diagnostics and issuing recommendations for adjusting the technological regime in order to optimize it are shown. The developed approach is aimed at increasing the information content of diagnostics and monitoring of sucker-rod pump units according to the wellhead dynamogram, which is especially important for wells operating in complicated operating conditions.With the help of a mathematical model, by approximating the calculated dynamogram to the actual one, it is possible to assess the criticality of complicating factors and further optimize the operating mode of the rod installation.
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