Retrievable Rotor ESP Stator Chamber Design
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Solution Overview
Problem
Artificial lift systems in wells often fail due to electrical system failures, leading to costly workover procedures and lost production, which can be avoided by isolating electrical components from hostile downhole environments.
Innovation Solution
The design of an electric submersible pump (ESP) with a stator chamber and rotor, where the rotor is retrievable while the stator remains in the well, and includes a coolant system and radial apertures to manage fluid flow and solid separation, with a magnetic bearing and damper to enhance reliability and reduce maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical components are placed in the downhole environment to enable pump operation, then the pump can function to increase fluid flow, but the electrical components are exposed to hostile conditions that cause failure and require workover procedures
Solution Approach 1:
The pump system is divided into two separate assemblies: a stator assembly that remains in the wellbore and a rotor assembly that can be retrieved. The stator assembly contains all electrical components (stator, electrical connection) and is isolated from the rotor assembly. This segmentation allows the electrical components to remain protected in the wellbore while the rotor can be independently retrieved for maintenance, resolving the contradiction between operational functionality and environmental exposure.
Solution Approach 2:
The rotor assembly, which contains no electrical components, is extracted as a separate retrievable unit from the wellbore environment. This extraction allows the rotor to be maintained or replaced without disturbing the stator assembly containing the electrical components, thereby protecting the electrical system from hostile downhole conditions while maintaining pump functionality.
2Reliability
If workover procedures are performed to replace failed equipment, then equipment reliability can be restored, but production is shut in resulting in lost revenue and time
Solution Approach 1:
By segmenting the pump into a stationary stator assembly and a movable rotor assembly, the system enables selective replacement of only the rotor when failure occurs. This segmentation allows rapid rotor retrieval and replacement without requiring complete workover procedures, thereby restoring reliability while minimizing production loss and time.
Solution Approach 2:
The rotor assembly is designed as a disposable or recoverable component that can be quickly removed and replaced. When the rotor fails, it is discarded or recovered for off-site repair, and a new rotor is installed without disturbing the stator assembly. This approach minimizes downtime and maintains continuous production while restoring equipment reliability.
3Reliability
If the stator chamber is sealed to protect electrical components, then electrical system reliability improves, but fluid flow management and cooling become more difficult
Solution Approach 1:
The stator chamber is sealed to protect electrical components, while the rotor assembly provides separate fluid flow paths. Fluid enters the rotor, flows through the impeller, and exits through the rotor outlet. This segmentation allows the stator chamber to be hermetically sealed for electrical protection while maintaining simple fluid flow management through the rotor's open architecture.
Solution Approach 2:
The rotor assembly acts as an intermediary between the sealed stator chamber and the wellbore environment. It provides the fluid flow path and cooling function without compromising the seal of the stator chamber. The rotor mediates between the need for electrical component protection and the need for fluid flow management, allowing both functions to coexist without increased complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration increases production reliability, reduces the frequency of workover procedures, and lowers maintenance and capital costs by separating electrical components from the hostile downhole environment, thereby extending the life of the well and minimizing lost production.
Implementation Method 1
The stator is configured to drive the rotor to rotate the impeller and induce well fluid flow in response to receiving power through the electrical connection
Implementation Method 2
The protector can include a bearing configured to control levitation of the rotor within the inner bore of the stator chamber
Data Source
AI summary
An electric submersible pump (ESP) is described. The ESP includes a stator chamber, a stator within the stator chamber, a rotor, and an electrical connection. The stator chamber is configured to reside in a wellbore. The stator chamber is configured to attach to a tubing of a well. The stator chamber defines an inner bore having an inner bore wall that, when the stator chamber is attached to the tubing, is continuous with an inner wall of the tubing. The rotor is positioned within the inner bore of the stator chamber. The rotor includes an impeller. The rotor is configured to be retrievable from the well while the stator remains in the well. The stator is configured to drive the rotor to rotate the impeller and induce well fluid flow in response to receiving power through the electrical connection.