Abstract

The first part of this paper is a reminder of the principle and the design of the Progressing Cavity Pump. It recalls the Moineau principle on which the pump works, describes the various parameters which define the pump and determine its performances. It shows the configuration used for oil production and indicates the range of practical performance that can, be expected.

The second part describes the results of three years of operations in Europe. It states the practical characteristics and advantages of the Progressing Cavity Pump as they have been observed and sometimes suggested by various users.

The third part deals with two recently developed pump models which broaden significantly the area of operation of the Progressing Cavity Pump :

  • The first one is a large capacity pump for high productivity and/or high water cut wells.

  • The second one is a high pressure pump for the production of high viscosity crude.

The presentation of the high pressure pump includes a discussion of the effects of high viscosity on the pump operation and of the solutions offered to optimize this operation.

PART I

The "Progressing Cavity Pump" (PCP) or "Eccentered Screw Pump" is also appropriately called "Rotary Submersible Moineau Pump".

As this type of lifting system is not yet widely known, it is useful to recall on which principle it operates, how it is implemented for oil production and what sort of performance one can expect from it.

Principle

The Moineau pump consists of two helices, one inside the other, which constitute a helical gear

  • the metal rotor, the internal one, is a simple helix,

  • the soft stator, the external one, is a double helix with twice the pitch length of the rotor.

Fig. 1 and 2 illustrate these two parts and their assembly.

The geometry of the assembly it such that it constitutes a series of identical, separate cavities. When the rotor is rotated inside the stator these cavities move axially from one end of the stator to the other, from suction to discharge, creating the pumping action.

Because the cavities are sealed from each other, the pump is of the positive displacement type.

The movement of the rotor inside the stator is actually a combination of two movements

  • a rotation around its own axis,

  • a rotation in the opposite direction of its own axis around the axis of the stator.

Therefore the name of "Eccentered Screw Pump" sometime used.

The geometry of the helical gear formed by the rotor and the stator is fully defined by the following parameters :

  • diameter of the rotor D

  • eccentricity E

  • pitch length of the stator P

The minimum length required for the pump to create effective pumping action is the pitch length it is, then, a one stage pump. Each additional pitch length results in an additional stage.

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