Deep-Well Pumping Operations

the mechanized raising of liquids (usually petroleum) from boreholes during the working of petroleum deposits. Sucker-rod borehole pumps and submersible centrifugal electric pumps are widely used in such operations; the latter are more productive.

In raising liquids by means of a sucker-rod borehole pump (Figure 1), a pipe with a cylinder and an intake valve at its base is lowered into the well. Within the cylinder are a piston plunger and a delivery valve. The plunger is connected by a

Figure 1. Diagram of installation using sucker-rod borehole pumps

long column of steel rods to the rocker of a pumping jack, which gives the plunger an up-and-down motion. The durability and deformation of the rods limit the scope of borehole

Figure 2. Diagram of installation of submersible centrifugal electric pump

pumps to depths of up to 3,200 m and an output of up to 20 cu m per 24 hours. Production of up to 500 cu m per 24 hours is possible at lesser depths (200-400 m).

The electric pump is a submersible centrifugal multistage pump (as many as 420 stages), which is lowered into the well on pipes (Figure 2). The shaft of the pump is rigidly connected to the shaft of a submersible electric motor with a power of up to 120 kilowatts. Transformer oil is poured into the body of the electric motor and is kept at a pressure of 0.1-0.2 meganewtons per sq m greater than the pressure at the depth to which the pump is submerged. An electric power cable is attached along the column of pipes. At the surface, near the wellhead, a transformer and a control station are installed with the required automatic equipment and devices to protect the installation against possible departures from normal operating conditions or breaks in the insulation. Usually such pumps are used where yields are in excess of 40 cu m per 24 hours.