Surface Liquid Yield Calculation Of Rod Pumping Wells Using Dynamometer Cards

It is essential to measure polished rod load and displacement constantly during rod pumping well operation. Surface liquid yield measurement using dynamometer card (SLYMUDC) is a method of computing surface liquid yield of wells by analyzing polished rod load and displacement. Since SLYMUDC can achieve well yield real-time, constantly, automatically and greatly reduce costs, it is most probably widely used in oil production. SLYMUDC is studied in this thesis, and the contributions and conclusion made as follows:The model of rod pumping system and its boundary conditions have great effect on the accuracy of SLYMUDC. Therefore, vertical well model and its dynamic characters are examined. Furthermore, the calculation of the load and displacement on the connections of rods is improved.The available plunger stroke length is one of the most important data in SLYMUDC. The relation between dynamometer card, opening / closing positions of valves and the available stroke length is discussed. Moreover, the model to calculate the curvature of pump dynamometer curve is shown. A method for available plunger stroke length calculation is presented, and a series of steps is provided.Due to the compressibility of liquid mixtures in tubing, the underground fluid volume is not equal to the surface liquid yield. A procedure can convert underground volume to surface liquid yield by computing volume coefficient of the mixture under discharge pressure is proposed. The effectiveness is verified by the data measured on oil well.Based on the investigations mentioned above, a surface liquid yield measurement system using dynamometer card is developed. The system is applied to analyze seventeen sets of data from twelve wells in four oilfields. The average relative error between the calculated and measured yield is 5.63%. The proposed system is suitable for oil production measurement.