ESP Diffuser Impeller Stiffness Balance
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Solution Overview
Problem
Electric submersible pumps (ESPs) operating in geologic environments face challenges due to transient and persistent conditions, such as the presence of condensed steam, which can impact their longevity and integrity, particularly in applications like steam-assisted gravity drainage (SAGD) systems where equipment must function effectively for extended periods.
Innovation Solution
The design incorporates a stack of diffusers and impellers with specific clearances and stiffness variations, including annular pistons and tolerance rings, to balance forces and manage fluid pressures, along with a controller system that monitors and adjusts operations based on fluid circuits and compliant components to maintain alignment and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the ESP operates in harsh geologic environments with condensed steam, then the equipment must function for extended periods, but the longevity and integrity of the equipment deteriorates due to thermal and mechanical stresses
Solution Approach 1:
The patent applies parameter changes by varying the stiffness of spacer components along the pump string. Different spacer stiffness values are selected based on the specific operational conditions and force balances required at different depths. This allows the pump system to adapt to varying thermal and mechanical stresses throughout its operational duration, maintaining reliability in harsh geologic environments.
Solution Approach 2:
The patent implements local quality by assigning different stiffness characteristics to different spacer components positioned at various locations along the pump string. Each spacer is tailored with specific stiffness properties suited to the local conditions it encounters, such as varying thermal gradients and mechanical loads at different depths, thereby optimizing both operational duration and equipment integrity.
2Productivity
If a stack of impellers and diffusers is used to propel fluid through stages, then pumping capability is improved, but force imbalance between stages causes mechanical stress and reduces reliability
Solution Approach 1:
The patent applies the counterweight principle by carefully selecting spacer stiffness values to balance the axial forces acting on the pump string. The spacers act as mechanical elements that counterbalance the forces generated by each impeller-diffuser stage, preventing force imbalance. This allows the multi-stage pump to maintain both high productivity and reliability by eliminating detrimental mechanical stresses.
3Strength
If rigid components are used to maintain structural integrity, then strength is improved, but thermal expansion and contraction cause misalignment and reduce operational stability
Solution Approach 1:
The patent implements dynamics by replacing rigid components with compliant spacer elements that can dynamically adapt to thermal conditions. These spacers possess controlled flexibility that allows them to accommodate thermal expansion and contraction while maintaining proper alignment. The dynamic compliance of the spacers ensures structural integrity is maintained without sacrificing alignment stability under varying thermal conditions.
Solution Approach 2:
The patent applies flexible elements in the form of compliant spacers that can deform elastically in response to thermal stresses. These flexible components maintain the necessary structural support while allowing for thermal movement, preventing misalignment and maintaining operational stability. The flexibility is carefully engineered to provide the right balance between strength and compliance.
Data Source
AI summary
An electric submersible pump (ESP) can include a shaft; an electric motor configured to rotatably drive the shaft; a housing; a stack of diffusers disposed in the housing; and impellers operatively coupled to the shaft. Various other apparatuses, systems, methods, etc., are also disclosed.