In this article, the last updated list of API & ISO standards for electrical submersible pump is presented. These standards can be considered as reference documents as well as a basis for training classes in the subject of electrical submersible pump.
The Motor seal is installed below the intake and above the electric motor. It is also named: Equalizer, balance chamber, or Protector. Seal section types, functions, components, and applications are detailed in this article.
In addition to the main function of transferring the motor torque to the pump shaft, the seal section performs four primary functions (Equalization, Expansion, Isolation, & “Aabsorbsion”):
PS: The motor, pump and seal are often submerged below several thousand feet of fluid. The seal section allows the pressure in the motor and the annulus to equalize, so that there is very little pressure across the shaft seals or the pothead connection.
PS: When selecting the protector, we need to be certain that the protector shaft is capable of delivering the full torque required without exceeding its yield strength which could result in a broken shaft.
Gas handling devices may be a better alternative for wells prone to high free gas, slugging, foams and emulsions. These are essentially centrifugal pumps with large stages, mixed (or axial) impellers, large vane openings, steep vane exit angles and sometimes include multiple vanes.
Instead of separating, their purpose is to break large gas bubble into smaller ones thereby reducing the risk of gas locking and making it easier for gas to be re-absorbed into solution, and to homogenize the gas with liquid phases, prior to entering the pump intake.
An additional benefit of gas handlers is, because more gas is retained in the flow stream, this gas is then available to help lift fluids in the tubing above the ESP discharge head thereby reducing hydraulic horsepower requirements.
Applications: A Gas Handler is generally considered if the Free Gas Percentage at the intake of the pump is from 30% to 60% by volume.
As the name suggests “ Pump Intake ” is where the well fluid enters the Submersible Pumping System. Care should be taken when designing a submersible pump intake because it is such a vital point in the system that when not designed properly may create all kinds of problems.
There are three types of intake Sections:
Standard intakes (BOI and integral) do not separate gas. Some gas separation might occur, but it will only be natural separation due to some of the gas not turning and going into the intake when the rest of the fluid does. Therefore, the standard intake is for wells that produce with a very low free gas to liquid ratio. The amount of free gas by volume at pump intake conditions should be no more than 10% to 15% by volume (depends if it is a radial or mixed flow stage)
Usually, the pump intake is a separate component that bolts onto the bottom of the pump section. Occasionally, the pump is built in either a lower tandem or single configuration. In these cases, the pump intake as an integral part of the pump assembly.
There are mainly two designs of electrical submersible pump stages widely used by ESP’s service companies:
