Page 56 - Petroleum and Gas Field Processing

Figure 22 Schematic of hydraulic pumping installation.

3. Electric Submersible Pumps (ESP): This method uses centrifugal
pumps powered by electric motors. The pump and motor are
both located at the bottom of the well and electric power is
provided to the motor from the surface through a special cable,
(Fig. 23). As with the HP, the function of the ESP is to increase
the pressure of the fluid so that it can move and reach the
surface with high pressure. The ESP is capable of producing very
high rates with a high surface pressure.
4. Gas Lift (GL): Although many different types of gas-lift
installation exist, the lifting concept is the same. High-pressure
gas is injected into the annular space between the casing
and tubing and enters the tubing, through special gas-lift valves
(Fig. 24). The gas mixes with fluids in the tubing, reducing its
density and, consequently, reducing the hydrostatic head
imposed by the fluid at the bottom of the well. The reduction

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