Progressing Cavity Pump Stator Coupling Assembly
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Solution Overview
Problem
Conventional progressing cavity pumps/motors with long lengths face difficulties in transportation and handling due to the complexity of aligning and connecting elongate stator sections, requiring specialized jigs and on-site welding, which is impractical for field applications.
Innovation Solution
A progressing cavity pump/motor design featuring structurally separable upper and lower stator tubes with a coupling assembly that includes an outer and inner sleeve with stop surfaces and threaded engagement, allowing for secure circumferential alignment and connection without the need for on-site welding or specialized jigs, using elastomeric materials for a fluid-tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the stator is made as a single elongate piece, then the pump/motor can achieve long length for deep well applications, but transportation and handling become difficult and require specialized jigs for alignment
Solution Approach 1:
The stator is divided into multiple separable sections (upper stator section and lower stator section) that can be transported and handled independently. Each section has a simplified structure that eliminates the need for specialized alignment jigs during assembly, while still achieving the required total length for deep well applications when connected through the coupling assembly.
2Strength
If the stator sections are connected using welding, then a permanent and strong connection is achieved, but on-site welding requires specialized equipment and increases complexity
Solution Approach 1:
The welding process is replaced with a mechanical coupling assembly consisting of an outer sleeve, inner sleeve, and fastening mechanism. This mechanical connection provides sufficient strength for downhole applications while eliminating the need for specialized welding equipment and procedures at the rig site, thereby reducing assembly complexity.
3Manufacturing precision
If the stator sections are aligned circumferentially during assembly, then proper rotation with the rotor is achieved, but alignment requires specialized jigs and precise positioning
Solution Approach 1:
The coupling assembly incorporates pre-formed circumferential alignment features (such as keyed surfaces or tapered interfaces) that automatically guide the stator sections into proper rotational alignment during assembly. This preliminary alignment mechanism eliminates the need for specialized positioning jigs and complex adjustment procedures at the assembly site.
4Reliability
If on-site welding is performed to connect stator sections, then a secure connection is achieved, but potential damage and safety risks increase
Solution Approach 1:
The welding process is replaced with a mechanical coupling assembly that provides a secure, reliable connection without the harmful effects of welding. This mechanical connection eliminates risks such as heat-affected zone damage, weld defects, and safety hazards associated with on-site welding operations, while maintaining connection reliability suitable for downhole environments.
Data Source
AI summary
A progressing cavity pump/motor includes an upper stator tube (14), a lower stator tube (16), a rotor (20) sitting between the upper and lower stator tubes, and a coupling assembly (30) interconnecting the stator tubes comprising an outer sleeve (32), an inner sleeve (36) and a nut (60) for threaded engagement with at least one of the sleeves to bring a stop surface on the inner sleeve into mating engagement with the stop surface on the outer sleeve. The pump/motor is usually assembled in the field while maintaining precise axial and rotational positioning of the stator tubes.