The article presents algorithm for calculating the pressure-flow characteristics, which will allow calculating the optimal speed of rotation of a progressing cavity pump (PCP) for oil production, depending on the swelling of the elastomer, the viscosity of the liquid and the gas content. To quantify the deviation of the actual feed and head values from the nominal values, the following coefficients are proposed: the flow deviation coefficient and the maximum pressure deviation coefficient. To quantify the influence of operating factors on the pressure characteristics of the proposed coefficients: the coefficient of swelling elastomer, coefficient of pressure in the working volume, the pressure coefficient on the rotational speed, the coefficient of pressure on the viscosity and the coefficient of pressure on the gas content. Based on analytical studies, it was found that the pressure and flow characteristics of PCP with uneven elastomer thickness significantly depend on the operating parameters. For example, the maximum pressure developed by the pump increases by 2–3 times with an increase in viscosity from 1 to 800 mPa∙s, and with a change in the flow deviation coefficient from 0.979 to 1.11, it decreases by 1.5–2 times. A change in the limit pressure causes a change in the speed of rotation necessary to ensure the calculated values of supply and pressure. The required speed to ensure the design values of supply and pressure for pumps with uneven elastomer thickness depends on operational factors to a greater extent for electric PCP than for sucker-rod screw pumps, with elastomer swelling being the most significant factor. For example, the rotation speed for electric PCP when the elastomer swells by 10 % can be reduced by 30 %, and for sucker-rod screw pump – by 21 %. The proposed algorithm for calculating the characteristics can be used in the development of a software product – a simulator of the pressure-flow characteristics of PCP.
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