# Eccentric Wear Mechanism and Centralizer Layout Design in 3D Curved Wellbores
## 4 Comparative Analysis of Application Cases
### Experiment Case 1. A1# Oil Well Engineering Design  
Application example 1 is A1# oil well of an oil production plant in Daqing Oilfield as shown in Table 1. The A1# oil well is located in a medium-deep oil reservoir, with a well depth of 990.6 metres. It exhibits relatively high formation pressure (10.53 MPa) and moderate formation temperature (54.62 \({}^{\circ}\)C). The produced fluid is predominantly characterised by a high water cut (99%), and the crude oil has a relative density of 0.85, classifying it as light crude oil. The associated gas production is relatively low, with a gas-oil ratio of 10.00 m\({}^{3}\)/m\({}^{3}\). The wellbore structure is designed appropriately, with a casing inner diameter of 124.00 mm and a tubing inner diameter of 76.00 mm, making it suitable for production during the high water cut phase. The production performance of oil well A1# after arranging centralisers according to the traditional design method is as follows (as shown in Table 2): This well utilises a pumping system with a stroke length of 4.20 m, a pump diameter of 38 mm, and a stroke frequency of 6.00 Hz, with the pump set at a depth of 900.05 m. Under these design operating conditions, the pump efficiency is 47.78%, and the system efficiency is relatively low at only 15%, with a daily liquid production of 19.65 m\({}^{3}\). The dynamic liquid level is at a depth of 650 m, with a liquid submergence depth of 250.05 m, and the maximum load is 28.07 kN. Overall, the traditional centraliser arrangement design has failed to effectively improve system efficiency, with both pump efficiency and liquid production remaining low, indicating room for further optimisation. \begin{table}
\begin{tabular}{c c c} \hline
**Specific Elements** & **Unit** & **Data** \\ \hline Medium-deep oil layer & m & 990.6 \\ Relative density of crude oil & \% & 0.85 \\ Production gas oil ratio & m\({}^{3}\)/m\({}^{3}\) & 10.00 \\ Casing inner diameter & mm & 124.00 \\ Formation pressure & MPa & 10.53 \\ Relative density of formation water & \% & 1.00 \\ Water cut & \% & 0.99 \\ Inner diameter of oil pipe & mm & 76.00 \\ Reservoir temperature & \({}^{\circ}\)C & 54.62 \\ Relative density of natural gas & \% & 0.70 \\ \hline \end{tabular}
\end{table} 
Table 1: Basic design parameters of oil wells (oil well A1#). The production status of oil well A1# after designing the centraliser arrangement according to the method described in this paper is as follows (as shown in Table 3): The well continues to use a pumping system with a stroke length of 4.20 m, a pump diameter of 38 mm, and a stroke frequency of 6.00 Hz, with a pump setting depth of 900.05 m. Under this design, the pump efficiency remains at 47.78%, but the system efficiency has increased to 20%, and the daily liquid production is maintained at 19.65 m\({}^{3}\). The dynamic liquid level has risen to 600 m, with the submergence depth increasing to 300.05 m, and the maximum load reduced to 24.52 kN. Overall, the centraliser arrangement designed using the method described in this paper has effectively improved system efficiency, reduced rod string load, and optimised production performance, demonstrating superior design results. The production status changes in oil well A1# under the traditional design method and the design method proposed in this paper are as follows: system efficiency increased by 5 percentage points, indicating a significant improvement; the dynamic liquid level depth rose from 650 m to 600 m, with a 20% increase in submergence; the maximum load was reduced by 12.65%, demonstrating an optimisation of the rod string's stress conditions. Pump efficiency and daily liquid production remained unchanged. The design method proposed in this paper significantly enhanced system efficiency, improved liquid level conditions, and reduced rod string load through the optimisation of centraliser arrangement, effectively improving overall production performance and operational stability.