The sucker rod serves as the slender component of a pumping well, connecting the polished rod at the top and the lower portion of the sucker pump to transfer power. Each individual sucker rod typically measures 7.62 or 8 meters, sometimes reaching up to 9.14 meters, and is usually made of low-carbon alloy steel that undergoes quenching and tempering treatment. These rods are connected sequentially using internal threaded couplings, extending all the way down to the piston located within the underground oil layer. The oil is extracted through a reciprocating motion. Nowadays, the depth of most oil wells averages around two kilometers, with some wells in places like the Shengli Oilfield reaching depths exceeding three thousand meters.
As a critical element of rod pumping equipment, the sucker rod transfers the power generated by the pumping unit to the downhole oil pump. A typical sucker rod string consists of dozens or even hundreds of these rods linked together via couplings. During oil production, the sucker rod string experiences asymmetrical cyclic loads, while also being exposed to the well fluid (a mixture of oil and formation water). In many cases, this fluid contains corrosive substances. Consequently, the primary modes of sucker rod failure often involve fatigue fractures or corrosion fatigue fractures. When a sucker rod breaks, it significantly disrupts oil production, inflates workover costs, and increases overall operational expenses.
Sucker rods have been in use for almost a century. The earliest versions were crafted from rattan. On October 30, 1894, Samuel M. Jones of Ohio received the Metal Sucker Rod Patent (U.S. 528168). Over the past two decades, both domestically and internationally, there have been numerous advancements in sucker rod manufacturing, including the use of multi-element alloy steels and fiberglass. New equipment and techniques such as intermediate frequency induction heating systems, infrared-guided intelligent thermometers, non-rotating sucker rod heads, fully automated coupling production lines, advanced forging die designs, external thread rolling processes, variable diameter elbows, half-cut and half-extruded coupling threads, friction welding, shot peening, and surface induction hardening have all contributed to improving the manufacturing standards and product quality of sucker rods.
To cater to the demands of high-volume, intensive pump operations, small pump deep well extraction, heavy oil wells, high wax content wells, corrosive wells, and deviated wells, various specialized sucker rods have been developed globally. These include ultra-high-strength sucker rods, FRP oil pumping rods, hollow sucker rods, KD-grade sucker rods, continuous sucker rods, electrically heated sucker rods, wire rope sucker rods, and aluminum alloy sucker rods. Additionally, many accessories for sucker rod strings have been researched, such as long-stroke high-strength polished rods, toothless polished rod clamps, rotary rod devices, shock absorbers, graphite-adjustable center polished rod sealing boxes, roller couplings, centralizers, wax scrapers, weighted rods, anti-falling devices, disconnecting devices, and magnetic anti-waxing tools. These innovations have extended the service life and broadened the application scope of sucker rods.
**Technical Principle**
Based on a high-strength sucker rod nipple as its core, HDNA boasts excellent tensile properties, with the sucker rod coupling having a diameter of 5/8 inch, which matches or surpasses the performance of standard sucker rods. By directly contacting the oil pipe and employing sacrificial anode electrochemical corrosion prevention, it mitigates electrochemical corrosion caused by localized wear. Through the electrolyte, the anode body provides cathodic current to the protected body, achieving cathodic protection. As the current flows continuously, the anode material is gradually consumed, effectively preventing damage to the sucker rod due to electrochemical corrosion. To shield the anode material from being washed away or impacted by fluids within the pipe, a stainless steel sleeve is installed around the inner and outer wire joints of the sucker rod and the anode body. Moreover, the coupling is made from high-nickel alloy, ensuring a smooth surface, which significantly enhances the lifespan of the sucker rod coupling.
**Technical Parameters**
- Size: 1", 7/8", 3/4", 5/8"
- Supporting rod diameter: 25mm, 22mm, 19mm, 16mm
- Centralizer outer diameter: φ56mm
- Sacrificial anode spontaneous potential protection range: 50m
- Effective power generation: ≥1.1 A.h/g
- Anode consumption rate: ≤12.36 kg/A.a
- Current efficiency: ≥65%
**On-Site Installation**
During sucker rod lowering operations, it must be connected and installed with the sucker rod screw. The installation section should be determined based on the corrosion and eccentric wear conditions of the oil well, with one section installed every 80-100 meters. The sucker rod anti-corrosion and anti-wear device performs optimally when used alongside the KXY-2 tubing cathodic protector and common nylon centralizers.
In recent years, with the increasing complexity of oil extraction environments, sucker rods have undergone significant technological advancements. These developments not only enhance their durability but also optimize their performance under extreme conditions. The integration of modern materials and advanced processing techniques has revolutionized the industry, making sucker rods more reliable and efficient. Furthermore, ongoing research into novel materials and methods continues to push the boundaries of what these essential components can achieve, ensuring they remain integral to the future of oil production worldwide.
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