Sucker Rod Anti - Buckling System Analysis
Research output: Research › Doctoral Thesis
Sucker rod pumps are worldwide with more than 80% the most important artificial lift method for oil production. Due to the material properties of steel and the dynamic behavior of the pumping system, the sucker rod string tends under compressive load to unwanted buckling effects. These in turn lead to increased wear of sucker rods and tubing string and are ultimately the cause of costly system damage. These in turn are primarily responsible for operating costs, thus lowering the efficiency and determine the economic limit of the well. The presented thesis deals with the numerical analysis of the overall sucker rod pumping system and the implementation of the patented "Sucker Rod Anti-Buckling System" (SRABS), which completely prevents buckling of sucker rods and increases the efficiency of the overall system essentially. Basically, this is achieved by a reconstruction of the standing valve of the subsurface pump, which now ensures a permanent tension of the rod string. The use of specially designed Downhole Dynamometer Sensors, which record beside the motion and load of the sucker rod string, the temperature profile along the complete length of the rod string, allows precise calibration of the self-developed simulation program for analyzing and predicting the behavior of such systems. The applied Finite Element Analysis in combination with the liquid - solid state - Interaction Simulation enables seamless observation of the dynamic behavior of sucker rod string. The results thus allow the technical and economic optimization of the system. The economic evaluation of the simulation results describes the significant savings that can be achieved through the use of SRABS. In addition to savings in energy consumption and the significant extension of the system service life, SRABS also improves the economic limit and increases the recovery factor of the field. The consequent reduction of the number of interventions to repair the well, having a demonstrably high risk of accidents, is a significant contribution to job safety.