During early oil exploration, because petroleum tend to have larger energy, so oil can flow from underground to overground auto automatic. With the continuous consumption of energy, it must add some energy to make the oil flow to the overground when the energy of its own is not sufficient. That's what we call as artificial lift methods.

1. The meaning of the artificial lift methods.

Artificial lift is artificially adding the energy to the bottom of the oil well to maintain a low production pressure, so that the oil can be obtained by the reservoir fluid from the formation. For the late period of the flowing wells or non flowing wells from the beginning due to the geological characteristics of the formation, we must install a suitable artificial lifting device for the exploitation of oil and gas.

2.Rod pump and sucker rod pump oil recovery technology

The rod pump oil recovery technology is mainly refers to the use of pumping rod’ up and down reciprocating motion to recovery the oil. The rodless pump oil recovery technology is the use of cable or high pressure liquid to transfer energy for pumping oil including the electric submersible pump, screw pump, hydraulic jetting, gas lift.

3.Screw pump technology

3.1The working principle of screw pump

The screw pump is a kind of volume pump, which is composed of two mutually engaged screw as the rotor and the stator. With the rotation of the rotor, the sealed inner cavity is moving by the suction side of the pump to the discharge end.When the screw pump works in the bottom fluid of oil well, the fluid is pressed into the screw pump to the opened chamber, and flow along with the axial of the chamber to the pump outlet under the action of the pump suction pressure

3.2The system of screw pump

The power device of ground driven screw pump is on the ground surface. Its original motion machine is generally the motor. Through different transmission mode, the motor's rotation is transferred to the driving head above the well, and then to the rotor of the screw pump to recover the oil by pumping rod. So it is composed of two major systems of overground and underground.

The systems of overground has three part including the transmission system, a driving head and a coupling. The systems of underground generally consists of stator, rotor, rotary drum, limiting device, sucker rod, sucker rod, stator stabilizer, tail pipe, sealing device, anchoring device and so on.

4.The electric submersible pump technology

4.1The working principle of electric submersible pump

The electric submersible pump technology is putting centrifugal pump and motor into the wells, then lifting oil onto the ground surface. It is an electric centrifugal pump that composed of multi-stage tandem impeller, which is similar to the working principle of ordinary centrifugal pump.

4.2The system of electric submersible pump

The underground part of electric submersible pump is mainly composed of the motor, submersible pump, protector, separator, pressure measuring device, power cable, single flow valve, valve pressure or discharge oil valve, centralizer, the cable shield. The overground part of electric submersible pump is mainly composed of distribution panel, transformer, control cabinet, inverter, junction box and oil production tree wellhead.

(1)The electric submersible pump motor

The electric submersible pump motor is also called submersible motor. It is the prime mover of electric submersible pump set and generally located on the bottom. Its working principle is turning the electric energy into mechanical energy as well as ordinary three-phase asynchronous motor.

(2)Submersible pump

Submersible pump is multi-stage centrifugal pump. The electric submersible pump is composed of several sections which every section is a centrifugal pump.

(3)Protector

Protector is specific to electric submersible pump. It is between the motor and the gas separator, the upper end is connected with the separator and the lower end is connected with the motor for protection.

(4)Gas separator

Gas separator, also known as the oil gas separator, is the pump inlet. It is located at the bottom of the submersible pump to separate the free gas from the fluid in the oil well.

(5)Measuring pressure apparatus

There are two categories of electric submersible pump pressure measuring system, one kind is electronic, the other kind is mechanical. It is mainly used to monitor the working temperature of the feed and the motor of the oil well.

(6)Check valve

Its role is mainly to maintain high enough back pressure which makes the pump to work at startup quickly in the designated point. It also can prevent fluid dropping caused by shutting down of the pump.

(7)Oil drain valve

It is the discharge port of the fluid in the tubing to reduce the load of the engine and prevent the pollution of the well.

(8)Power cable

The motor is connected with the ground power supply and control system, which is the channel to transmit the power and the PSI/PHD signal.

(9)Cable guard

The cable guard and the cable is fixed on the outer surface of the tubing together through the bandage, cable to prevent mechanical damage in the process of entering well.

(10)Centralizer

The centralizer is mainly used for slope which is located in the end of the motor. It keeps motor staying in the middle so that the external flow of the motor will be well-distributed to prevent the damage to the motor caused by partial high temperature.

5.Other techniques of artificial lift

5.1Hydraulic jet pump

Hydraulic jet pump is a special kind of hydraulic pump which is also called as jet pump. Jet pump can transfer the high pressure potential energy into high - speed kinetic energy through the nozzle. In the piping, high speed and low speed power fluid fluid mix and exchange momentum. The kinetic energy is converted to static pressure by the diffusion tube and the mixture is collected to the ground.

5.2Gas lift production

Gas lift oil production is injecting the high pressure gas from the ground into the flowing stop oil wells in order to reduce the oil pressure gradient in the lifting pipe. Based on the principle of U type tube, high pressure gas is injected into oil tube through ground. Then to make it mixed with the formation fluid to reduce the liquid column density and the back pressure of the bottom hole and establish the production pressure difference between the liquid and the ground. 

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