Progressing Cavity Pump Rotor Positioning via Top-Tag Coupling
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Solution Overview
Problem
Existing progressing cavity pumps face challenges in accurately axially positioning the rotor within the stator, particularly when run-in on a rod string, due to interference issues that can hinder the run-in and operation of the pump.
Innovation Solution
A top-tag coupling assembly is introduced, featuring a rotor head that tags onto a narrowing shoulder section of a tubing string collar above the stator, allowing for precise alignment and reduced interference, with a collar assembly that forms a pathway similar to the stator's helical path, enabling smooth run-in and operation by eliminating the need for a tagging pin or plate below the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a tagging pin or plate is used below the stator for rotor positioning, then the rotor can be axially positioned, but fluid intake is restricted and production is reduced
Solution Approach 1:
The patent inverts the traditional positioning approach by moving the tagging mechanism from below the stator (where it restricted fluid intake) to above the stator (where it does not interfere with fluid flow). The rotor head with its stop engages with the tag shoulder positioned above the stator, allowing precise axial positioning without blocking the fluid intake path, thus resolving the contradiction between positioning precision and production capability
2Measurement precision
If a traditional tagging pin or plate is used for rotor positioning, then the rotor location can be confirmed, but assembly complexity increases and equipment passage is obstructed
Solution Approach 1:
The patent merges the tagging function with the existing collar assembly structure. The tag shoulder is integrated into the collar assembly above the stator, eliminating the need for separate tagging pins or plates. This integration simplifies the overall assembly by combining positioning functionality into an existing component, reducing the number of parts and assembly steps while maintaining accurate rotor location confirmation
Solution Approach 2:
The patent extracts the tagging function from the below-stator region and relocates it to the above-stator region. By removing the tagging pin or plate from the traditional position and repositioning it in the collar assembly above the stator, the design eliminates obstructions to equipment passage and simplifies assembly while preserving the essential rotor positioning capability
3Manufacturing precision
If the rotor is lowered on rods until the stop lands on the tag shoulder, then axial positioning is achieved, but interference may occur during run-in
Solution Approach 1:
The patent applies local quality by creating a narrowing tag shoulder with specific geometric characteristics (reduced diameter) that matches the rotor head's stop. This localized geometric feature provides precise positioning while the narrowing design allows the rotor to pass through during run-in without interference, as the tag shoulder closely approximates the rotor's helical path. The local geometric optimization resolves the contradiction between positioning accuracy and run-in smoothness
Data Source
AI summary
A progressing cavity pump assembly includes a collar assembly connecting a housing and a tubing string, with the collar having an inside diameter upset and the rotor having a rotor head axially spaced from a rotor helix, with the rotor head having an outer diameter forming a stop adapted to land on the inside diameter upset. A method of timing a progressing cavity pump assembly includes providing a collar assembly having an inside diameter upset, movably connecting the collar assembly and the housing, providing a rotor having a rotor head axially spaced from a rotor helix, with the rotor head having an outer diameter forming a stop, selectively adjusting the relative position of the collar assembly and the housing to form a pathway substantially corresponding to the rotor helix, landing the stop on the inside diameter upset, and fixing the relative position of the collar assembly and the housing.