In order to maintain stable oilfield production, aimming the easy occurrence of the long-stroke sucker rod hysteresis during oil extraction, which reduced production efficiency, a mass-slider model was introduced. Analytical solutions were compared with numerical solutions by using the equivalent COMBIN40 element at different time points. The error was less than 0.1% between the two results, indicating that the COMBIN40 element accurately described the motion of the long-stroke sucker rod with Coulomb damping. Considering the geometric nonlinearity of the sucker rod string in three-dimensional space and the contact nonlinearity between the rod and the tubing, the COMBIN40 element was introduced to discretize the long-stroke sucker rod string. The axial inertia, elastic deformation, and frictional characteristics of the sucker rod string were represented simultaneously within a single element by taking advantage of the multi-physical coupling capability for the COMBIN40 element. Only the axial freedom of motion needed to be defined, which significantly reduced the dimensionality of the global equations and the computational complexity. This approach resolved the low computational efficiency problem by using the conventional BEAM188 element. The time domain was discretized using the Newmark method. A cyclic iteration method based on nodal loads and displacements was employed to solve the system. Using actual production parameters as boundary conditions, the surface dynamometer card was obtained through simulation and compared with the measured dynamometer card. The calculated and measured results were found to be in close agreement. The operating parameters of sucker rod strings was simulated in eight high-deviation, long-stroke, low-frequency wells of the Daqing Oilfield. The motion parameters of the sucker rods were obtained under varying stroke lengths, stroke frequencies, produced fluid viscosities, pump diameters and well deviation angles. The results show that, as the stroke, stroke frequency, produced fluid viscosity, pump diameter, and well deviation angle increased, the downstroke friction of the sucker rods also increased, and the hysteresis effect became more pronounced. These findings provide a theoretical basis for analyzing the downward hysteresis of long-stroke sucker rods in the field.
WANG Gang, YUE Qian-bei, XU Ping-wen, CHEN Zhong, LIU Ju-bao, ZHAO Zhi-wei, NIE Xi-jian.
Simulation on Downward Hysteresis of Long-stroke Sucker Rod Based on COMBIN40 Element Equivalent Band with Coulomb Damping[J].
Science Technology and Engineering, 2026, 26(23): 9912-9927 DOI:10.12404/j.issn.1671-1815.2506898
$ F_{\mathrm{u}}(t)=\rho_{\mathrm{L}} g L_{\mathrm{P}}(t)\left(A_{\mathrm{P}}-A_{\mathrm{r}}\right)-\rho_{\mathrm{L}} g L_{\mathrm{m}}(t) A_{\mathrm{P}}+F_{\mathrm{ZB}}$
$ F_{\mathrm{d}}(t)=-\rho_{\mathrm{L}} g L_{\mathrm{P}}(t) A_{\mathrm{r}}-F_{\mathrm{g} \mathrm{lzl}}(t)-F_{\mathrm{ZB}}$
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