A sucker rod is a vital component in the oil and gas industry, particularly in onshore operations, where it facilitates the extraction of oil from wells. Sucker rods are long, slender metal rods, typically made of high-strength steel, that connect the surface pump jack to the downhole pump in a well. When the pump jack at the surface moves up and down, it transfers this motion to the sucker rod, which drives the reciprocating pump at the well's bottom, effectively lifting oil to the surface. Due to their critical role, sucker rods are engineered to withstand high levels of stress, abrasion, and the often-corrosive environments found in oil wells.

There are various types of sucker rods, each suited for different well conditions and depths. Traditional sucker rods are usually manufactured from carbon or alloy steel and come in standard lengths of around 25 to 30 feet, with threaded ends for joining in a long string to reach depths exceeding several thousand feet. For deeper or more challenging wells, high-strength, corrosion-resistant rods, such as those made from fiberglass or special alloy materials, may be used. Fiberglass rods are beneficial in reducing weight while enhancing corrosion resistance, though they may not be as strong under certain high-stress conditions as alloy steel rods.

One of the significant challenges in the use of sucker rods is fatigue failure. As these rods move up and down with every pump stroke, they experience cyclic stresses, which can lead to metal fatigue over time. This is particularly problematic in wells with high fluid loads or where corrosive elements such as hydrogen sulfide or CO₂ are present. To mitigate fatigue issues, operators may use specially designed rods with optimized geometries, protective coatings, or periodic maintenance practices that involve replacing worn-out sections. Additionally, some wells employ sucker rod guides, which stabilize the rod and reduce wear by preventing direct contact with the tubing.

The connection points between sucker rods, known as rod couplings, are another area of focus in sucker rod design and maintenance. These couplings are typically threaded and must be assembled with precision to ensure reliable operation. Loose or improperly fastened couplings can lead to failures and disruptions in oil production. Innovations in rod coupling technology, such as using high-strength materials or anti-galling coatings, have helped improve the longevity and reliability of sucker rod assemblies. Additionally, rod coupling inspections and regular maintenance are crucial for ensuring the continuous functioning of the rod string.