Pumping unit is a ground-driven equipment with rod pumping. According to the basic structure of the oil pumping unit, the oil pumping unit can be divided into two categories: Free beam type and non-free beam type. The most widely used at home and abroad is the free beam type oil pumping unit (commonly known as kowtow machine). So today, let's take a closer look at the different types of beam-type pumps that can be used on rod pumps.
According to the different structural forms, the beam pumping unit is divided into conventional type (ordinary type), out-of-phase type and front type. The conventional type and the front type are the two basic types of beam-type oil pumping units.
(1) Conventional beam pumping unit：
Conventional beam-type oil pumping unit is one of the most widely used oil pumping units in oil fields.Its structural characteristics are: the bracket is located in the middle of the travel beam, the donkey head and the crank connecting rod are located at both ends of the travel beam, and the center of the crank shaft is basically located directly below the tail bearing of the travel beam, and the upper and lower stroke running time is equal.
The beam-type oil pump is mainly composed of four parts: a beam-type connecting rod and a crank mechanism, a deceleration mechanism (reducer), power equipment (motor) and auxiliary devices. When the beam-type oil pump is working, the motor (or other power machine) transmits the high-speed rotational movement to the input shaft of the reducer through the transmission belt. After deceleration, the low-speed rotating crank drives the beam to swing up and down through the four-link mechanism.
Like this type of pumping unit, we usually recommend it for conventional oil wells with a depth of ≤2000 meters, and it has good tolerance to formations with medium sand content.
(2) Out-of-phase beam pumping unit：
Out-of-phase cruise-beam oil pumping unit is a kind of oil pumping unit with good performance developed in the 1970s.From the appearance point of view, it is not significantly different from the conventional beam-type pumping unit, so the conventional type and the out-of-phase type are also called rear-mounted pumping units.The structural characteristics of the out-of-phase traveling beam pumping unit are: there is a certain horizontal distance between the center of the crank shaft and the tail bearing of the traveling beam; there is an offset angle between the centerline of the crank balance arm and the centerline of the crank (crank balance phase angle). The crank angle of the upper stroke is significantly greater than that of the lower stroke, thereby reducing the operating speed, acceleration and dynamic load of the upper stroke, and achieving the purpose of reducing the load of the pumping unit, extending the life of the pumping rod and saving energy.
Because of its good dynamic characteristics and load adaptability, out-of-phase beam pumping units are usually widely used in the mining of medium and deep wells and complex well conditions. The types of rod pumps adapted include conventional rod pumps, sand-proof rod pumps, air anchor rod pumps and long-stroke rod pumps. The specific selection needs to be configured in accordance with downhole conditions and production requirements. Through scientific selection and refined management, the synergistic effect of out-of-phase beam pumping unit and rod pump can be fully utilized to improve oil recovery efficiency and reduce operating costs.
(3) Front-mounted beam-type oil pumping unit：
The structural characteristics of the front-mounted travel beam pumping unit are: the bracket is located at one end of the travel beam, and the donkey head and the crank connecting rod are located at the other end. Under the same crank radius, the stroke length of the front type is significantly larger than that of the conventional type, and the specifications and dimensions of the pumping unit are smaller than that of the conventional type. The upper stroke running time of this pumping unit is longer than the lower stroke running time, thereby reducing the upper stroke.
The operating speed, acceleration and dynamic load of the process. The front-mounted type is mostly heavy-duty long-stroke oil pumping units, which use pneumatic balance in addition to mechanical balance.
In order to increase the stroke, save energy, and improve the structural characteristics and force state of the pumping unit, many deformed beam pumping units have also appeared at home and abroad, such as double donkey head type, rotating donkey head type, large wheel donkey head type, large wheel type and oblique straight well beam pumping unit.
In order to expand the scope of application of rod pump pumping and improve its technical and economic indicators, many different types of non-beam pumping units (especially ultra-long-stroke pumping units) have been developed at home and abroad, such as chain type, range-increasing type and broadband type pumping unit, the main characteristics are mostly long-stroke and slow-stroke times, in order to meet the special needs of deep wells and heavy oil.