API Subsurface Pump Designation

The pump designation is part of API Spec 11AX and describes the main specifications of an API subsurface pump. It is a nomenclature to classify API sucker rod pumps and tubing pumps according to their main characteristics. It is comprised of seven parts, separated by dashes.
Example: 20-125-RHBC-10-4-2-2

Each part, in order, describes the following specifications:

  • Nominal tubing size (inch – given as a key representing the actual size)
  • Basic bore size (inch)
  • Type of pumptype of barrellocation and type of seating assembly (letter code)
  • Barrel length (ft)
  • Plunger length (ft)
  • Length of upper extension, used with heavy-wall barrel (inch)
  • Length of lower extension, used with heavy-wall barrel (inch)

 

Example: A 1 1⁄4 in. (31.8 mm) bore rod type pump with a 10 ft (3.048 m) heavy wall barrel and 2 ft (0.610 m) upper extension, 2ft (0.610 m) lower extension, a 4 ft (1.219 m) plunger, and a bottom cup type seating assembly for operation in 2 3⁄8 in. (60.3 mm) tubing, would be designated as follows:

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Surface Components of Sucker Rod Pumps in different languages

The working principle of a sucker rod pumping unit, as well as its components, have been detailed in a previous article titled: “Beam Pumping Unit Principles and Components”. This article will focus on the names of surface components of sucker rod pumps used in different languages, namely: Arabic, English, and French.

NB: As a reminder, beam pumping unit is a machine for translating rotary motion from a crankshaft to a linear reciprocating motion for the purpose of transferring mechanical power to a down-hole pump. The purpose, simply stated, of the basic system is to transmit energy from the surface to the downhole pump.

The following figure depicts the main components of a surface sucker rod pumping unit (conventional type in this case).

The following table presents the names of surface components of sucker rod pumps  Arabic, English, and French languages:

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10 Types of Rod Pumping Units

1. Conventional Unit:

The conventional pumping unit is a modern version of the beam pumping unit first built in 1926 with the invention of crank counterbalance.  It is a rear mounted class 1 lever system with crank counterbalance.

Typically, if one were to drop a plumb line off the equalizer bearing that line would fall over the center of the crankshaft. This machine can be rotated both Clockwise (CW) and Counterclockwise (CCW) with approximately the same performance characteristics.

It is manufactured in a wide variety of sizes and it can be fitted with many types of prime-mover bases that attach to the normal unit base.

This is the most common pumping unit type, because of its relative simplicity of operation, low maintenance requirements and adaptability to a wide range of field applications. As the cranks on a conventional unit rotate, the pitman side members cause the walking beam to pivot on a center bearing, moving the polished rod. Adjustable counterweights are located on the cranks.

As detailed by the article titled “Beam Pumping Unit Principles and Components“, most important parts of the conventional units are: Base, Counterweight, Crank, Samson Post, Horse Head, Walking Beam, Equalizer, Pitman, Gear Reducer, Brake and Prime Mover.

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Beam Pumping Unit Principles and Components

Beam pumping Unit Principles:

A beam pumping unit is a machine for translating rotary motion from a crankshaft to linear reciprocating motion for the purpose of transferring mechanical power to a down-hole pump.

The purpose, simply stated, of the basic system is to transmit energy from the surface to the downhole pump.  The resulting configuration has been referred to as a Sucker Rod Pumping System.

Beam pumping Unit Components:

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Back Pressure Regulators for Gassy Sucker Rod Lifted Wells

The problem of heading (flow off and pump) is often encountered in gassy wells. This heading effect which can blow the tubing dry occurs as follows:

  • Gas expansion in the tubing as oil from the reservoir travels towards the surface (due to gas pressure decrease).
  • Formation of a gas “plunger” that can push the liquid above it out of the tubing and into the flow line at high speed. As the gas forces the liquids out of the tubing, the pressure in the tubing decreases rapidly and the gas expands even more.
  • This heading behavior of reservoir fluids causes cycles of high production followed by low or no production.

When heading process starts, the expanding gas pushes the liquid into the flowlines and increases production for a short time. In the meantime, the liquid leaving the tubing is replaced by more and more free gas. Eventually, the tubing is blown dry and production stops until the tubing fills with liquid again.

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