A sucker rod is a steel rod, typically between 25 and 30 feet (7 to 9 meters) in length, and threaded at both ends, used in the oil industry to join together the surface and downhole components of a reciprocating piston pump installed in an oil well. The pumpjack is the visible above-ground drive for the well pump, and is connected to the downhole pump at the bottom of the well by a series of interconnected sucker rods. Sucker rods are also commonly available made of fiberglass in 37 1/2 foot lengths and diameters of 3/4, 7/8, 1, and 1 1/4 inch. These are terminated in metallic threaded ends, female at one end and male at the other.
The surface unit transfers energy for pumping the well from the prime-mover to the sucker rod string. In doing this, it must change the rotary motion of the prime-mover to reciprocating motion for the sucker rod. And it must reduce the speed of the prime-mover to a suitable pumping speed. Speed reduction is accomplished by using a gear reducer, and rotary motion of the crank shaft is converted to oscillatory motion by means of a walking beam. The crank arm is connected to the walking beam by means of a pitman arm. The walking beam is supported by a Samson post and saddle bearing. The horse head and bridle are used to ensure that the pull on the sucker rod string is vertical at all times so that no bearing movement is applied to that part of the sucker rod string above the stuffing box. The polished rod and stuffing box combination is used to maintain a good liquid seal at the surface.
Various types of these rods are available, each designed to meet specific operational requirements and conditions in the oil and gas industry. Here are some common types:
Standard Rods
Standard rods are the most commonly used type. They are made of high-strength carbon or alloy steel and come in different sizes and lengths. Standard rods are typically solid, meaning they have a continuous body without hollow sections.
These rods are suitable for most well conditions and provide reliable performance in typical oil and gas production operations.
Hollow Rods
Hollow rods have a hollow interior, offering advantages in specific well situations. They are lighter than standard rods, which can reduce the load on the pumping unit and improve pumping efficiency.
Hollow rods are often used in wells with high fluid volumes, viscous fluids or when there is a need to reduce the weight of the rod string.
Continuous Rods
Continuous rods are specially designed for wells with deviated or crooked boreholes. These rods have flexible joints or couplings that allow them to bend and accommodate the wellbore's shape without the risk of breakage.
Continuous rods help minimize the stress and fatigue in deviated wells, ensuring reliable and continuous operation.
Spray Metal or Fiberglass Rods
Fiberglass or spray metal rods are used in corrosive or high-temperature environments where traditional steel rods may not be suitable. Spray metal rods are coated with a layer of corrosion-resistant material, such as aluminum, to protect against chemical reactions.
Fiberglass rods are composite materials that offer excellent corrosion resistance and strength. These alternative materials provide durability and performance in harsh well conditions.
Polished Rods
Polished rods are not technically rods but are an integral part of the rod string. They connect the downhole pump to the rod string and transmit the reciprocating motion from the surface unit.
Polished rods are usually steel and have a smooth, polished surface to minimize wear and friction between the rod string and the pumping unit.
Importance of Sucker Rod
Production Efficiency
Rod pumping systems are widely used for artificial lift operations worldwide, making them a vital tool for increasing production efficiency. They allow for the economic recovery of oil and gas resources, even from low-pressure reservoirs.
Versatility
These rods are compatible with various downhole pumps, making them versatile for different well conditions and reservoir characteristics. They can be tailored to specific well depths, fluid viscosities, and production rates.
Cost-Effectiveness
These rod systems are relatively simple and cost-effective compared to other artificial lift methods. They require less initial investment and maintenance, making them suitable for onshore and offshore applications.
Durability and Reliability
Rods are engineered to withstand harsh downhole conditions, including high loads, corrosive environments, and extreme temperatures. Their strength and durability ensure long-lasting and reliable operation.
Artificial Lift
These rods are an integral part of the artificial lift system, which helps overcome the natural decline in well pressure over time. By transmitting the reciprocating motion from the surface to the downhole pump, rods create the necessary pressure differentials to lift fluids, including oil, to the surface.
Monitoring Capabilities
These rods provide a means for monitoring downhole conditions. By analyzing the rod's behavior, including vibrations, load, and stress, operators can gain valuable insights into well performance, downhole conditions, and potential issues like rod fatigue or pump failures.
Load Bearing and Stability
Rods are subjected to significant operational stresses, such as tension, compression, and bending forces. They must withstand these loads while maintaining structural integrity. High-quality rods possess excellent strength, durability, and resistance to corrosion, ensuring their reliability and longevity under challenging downhole conditions.
Transferring Power
Rods are a conduit for transferring mechanical power from the surface pumping unit to the downhole pump. This power is used to lift the fluids, such as oil and gas, to the surface. As the surface unit reciprocates, it gives up-and-down motion to the rods, which drives the downhole pump.
Sucker rods from Vigor use the Norris standard, which is the most widely recognized standard for sucker rods. Up to now, our sucker rod has been used in many oilfields in the Americas, Europe, Asia and Africa, Vigor's sucker rod has been unanimously recognized and affirmed by customers, there are a number of internationally renowned oilfield service companies and Vigor to reach long-term cooperation, if you are interested in Vigor's services or oil and gas downhole drilling and completion tools, please do not hesitate to get in touch with us to get the best quality products and the top technical support.
