Sucker rod
The sucker rod is an elongated rod of the pumping well, which is connected to the main rod and is connected to the pump to transmit power. The length of the sucker rod is six meters. The material is usually hard chrome plated on the surface of high carbon steel. It is connected with the internal thread hoop in the oil pipe and extends to the piston at the underground oil layer. The oil is pumped by reciprocating motion. The current length of the oil well is generally about two kilometers. Take Shengli Oilfield as an example, the deepest is more than 3,000 meters.
Sucker Rod Development History
The sucker rod is an important part of the rod pumping equipment, which transmits the power of the pumping unit to the downhole pump. The sucker rod column is made up of dozens or hundreds of sucker rods connected by couplings. During the oil recovery process, the sucker rod column is subjected to asymmetric cyclic loading. The working medium is well fluid (crude oil and ore water), and the well fluid of many pumping wells contains corrosive media. Therefore, the main failure mode of the sucker rod is fatigue fracture or corrosion fatigue fracture. The disconnection of the sucker rod will seriously affect the crude oil production, increase the cost of workover, and increase the cost of crude oil.
Sucker rods have a history of nearly a hundred years. The most original salt-dried rods are made of rattan. The first metal sucker rod patent (U.S. 528168) was acquired on October 30, 1894 by Samuel M. Jones of the State of Ohio, USA. In the past 20 years, many new materials, new equipment, new technologies and new processes have been used in the manufacture of sucker rods at home and abroad, such as multi-element alloy steel and glass steel; medium-frequency induction diathermy heating and automatic flat forging machines. Forging, using medium frequency induction heating quenching device and infrared light guide intelligent temperature measuring instrument, sucker rod head non-rotating processing production line, coupling automatic production line; and advanced forging die design technology, sucker rod external thread rolling process, coupling. The internal thread half-cutting and semi-extrusion process, the friction welding process, the shot peening process, and the surface induction hardening process greatly improve the manufacturing level and product quality of the sucker rod.
In order to meet the needs of large pump mining, small pump deep pumping, heavy oil wells, high-containing wax wells, corrosion wells and inclined wells, many special sucker rods have been developed, such as ultra-high-strength sucker rods and glass steel pumping. Rods, hollow sucker rods, KD-class sucker rods, continuous sucker rods, electric sucker rods, wire rope sucker rods and aluminum alloy sucker rods, etc., and many supporting parts of sucker rod columns, such as long strokes High-intensity polished rod, edentulous rod clamp, rotary rod, shock absorber, graphite adjustable heart rod sealing box, roller coupling, centralizer, wax scraper, weighting rod, anti-offset, disconnector, magnetic wax proof The pump and the pump air controller, etc., further improve the service life and application range of the sucker rod.
Sucker Rod Structure and Application
The sucker rod is an important part of the rod pumping equipment. The sucker rod is connected to the sucker rod column through the coupling, and the upper rod is connected to the pumping unit through the light rod, and the plunger of the pumping pump is connected, and the function is to transmit the reciprocating motion of the ground pumping unit to the downhole oil pump.
Sucker rod thread failure often manifests as a thread pull. However, due to the lower recessed design of the thread of the modern API sucker rod and the use of rolling instead of turning when manufacturing the thread, the occurrence of such problems has been greatly reduced.
The common sucker rod and its head structure are shown below.
