What Is a Rod Pump?

The rod pump generally refers to a plunger type oil pump driven by the up and down reciprocating movement of a sucker rod. Rod pump oil extraction has the characteristics of simple structure, strong adaptability, convenient maintenance management, and long life. It is currently the most widely used mechanical oil extraction method at home and abroad. Rod pump is the most commonly used single-cylinder single-acting oil pump, and its oil discharge capacity depends on the pump diameter and the stroke and number of strokes. The efficiency of the pump in medium and deep wells is about 50%, which is suitable for medium and low production wells.

Rod pump

The rod pump generally refers to a plunger type oil pump driven by the up and down reciprocating movement of a sucker rod. Rod pump oil extraction has the characteristics of simple structure, strong adaptability, convenient maintenance and management, and long life. It is currently the most widely used mechanical oil extraction method at home and abroad. Rod pump is the most commonly used single-cylinder single-acting oil pump, and its oil discharge capacity depends on the pump diameter and the stroke and number of strokes. The efficiency of the pump in medium and deep wells is about 50%, which is suitable for medium and low production wells.

Chinese name

Rod pump

Foreign name

sucker rod pump

Industry

Oil extraction

Other name

Suction pump

effectiveness

Around 50%

component

Pumping unit, sucker rod string

A typical rod pumping unit consists of three parts

First, the ground drive equipment is the pumping unit;

The second is an oil pump installed in the lower part of the tubing string;

The third is the sucker rod string, which transmits the motion and power of the surface equipment to the downhole pump pump plunger to make it reciprocate up and down, pressurize the liquid in the tubing string, and pump the oil produced fluid to the ground. In terms of the entire rod-pumped production system, it also includes the oil layer that supplies the fluid, the tubing string used to suspend the pump and act as a lifting fluid channel, downhole appliances (tubing anchors, gas anchors, sand anchors, etc.), and oil jackets. Pipe annular space and wellhead equipment.

Pumping unit (pumping unit) is a ground driven equipment with rod pumping. According to its basic structure, the pumping unit can be divided into two types: beam-pumping type and beamless type. At present, the most widely used at home and abroad is the beam-pumping type (commonly known as the hoe). The beam pumping unit is mainly composed of four parts: beam-link-crank (four-link) mechanism, reduction mechanism (reducer), power equipment (motor) and auxiliary devices, as shown in Figure 2. When the beam pumping unit works, the motor (or other power machine) transmits high-speed rotary motion to the input shaft of the reducer through a transmission belt. After deceleration, the crank that rotates at a low speed drives the beam to reciprocate up and down through a four-link mechanism. . The arc-shaped donkey head at the front end of the beam drives the sucker rod string to reciprocate linear motion up and down through the rope suspension device.

According to different structural forms, beam pumping units are divided into conventional (ordinary), out-of-phase and front-mounted. The conventional type and the front type are the two basic types of beam pumping units.

(I) Conventional beam pumping unit

Conventional beam pumping unit is the most widely used type of pumping unit in oil fields. Its structural features are: the bracket is located in the middle of the beam, the donkey head and the crank link are located at the two ends of the beam, the center of the crank shaft is basically directly below the tail bearing of the beam, and the up and down stroke running time is equal.

The beam pumping unit is mainly composed of four parts: a beam, a connecting rod, a crank mechanism, a reduction mechanism (reducer), a power equipment (motor), and auxiliary devices. When the beam pumping unit works, the motor (or other power unit) ) The high-speed rotary motion is transmitted to the input shaft of the reducer through a transmission belt. After deceleration, the crank that rotates at a low speed drives the beam to reciprocate up and down through a four-link mechanism.

(Two) out-of-phase beam pumping unit

Sucker rod pump is a key downhole equipment with rod pumping system. It is installed in the lower part of the tubing string and is sunk in the well fluid. It is pumped in the well by the power transmitted by the pumping unit and the sucker rod. liquid. The liquid it pumps often contains wax, sand, gas, water, and corrosive substances. It also works downholes from hundreds of meters to thousands of kilometers, and the internal pressure of the pump is sometimes as high as 10 MPa or more. In order to adapt the pumping pump to the complex working environment and harsh conditions downhole, the basic requirements for the pumping pump are: simple structure, high strength; reliable work, long service life; easy to start and the specifications can meet the needs of the oilfield's oil production process .

(Two) the working principle of the pump

The ordinary sucker rod is connected to form a sucker rod string through a coupling, the upper part is connected to the pumping unit through the smooth rod, and the plunger of the sucker pump is connected to the bottom, and its role is to transmit the reciprocating motion of the suspension point of the ground pumping unit to Downhole oil pump.

The rod body of a common sucker rod is a steel rod with a solid circular cross section, which is characterized by simple structure, easy manufacture and low cost. It is mainly used for conventional rod pumping.

Working process of rod pump

In order to meet the needs of high water content, heavy oil, high wax content, corrosive media, and deep and inclined well production, many special domestic and foreign sucker rods with different structures, materials, and uses than ordinary sucker rods have been applied, such as ultra-high strength. Sucker rod, FRP sucker rod, hollow sucker rod and continuous sucker rod, etc.

In the sucker rod string, in addition to the sucker rod string and the coupling, there are some auxiliary devices, mainly including:

(1) Bare. It is located at the uppermost end of the sucker rod, and its role is to connect the donkey head steel wire rope with the sucker rod under the well, and cooperate with the wellhead packing to seal the sucker wellhead. Therefore, higher strength and surface finish are required.

(2) Weight bar. It is used for large pumps, heavy oil wells and deep wells. The lower part of the sucker rod string uses weighting rods to prevent longitudinal bending of the lower part of the sucker rod string and reduce the breakage of the sucker rod.

(3) Sucker rod centralizer. It is used in inclined wells and cluster wells to keep the sucker rod in the center of the tubing and not directly contact the tubing, reducing wear, vibration and bending of the sucker rod.

In addition, there are shock absorbers for reducing the vibration of the sucker rod, and anti-dropouts to prevent the sucker rod coupling from loosening.