Submersible Pump Motor Cooling via External Oil Circulation Tubes
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Solution Overview
Problem
Existing external cooling devices for submersible pump motors in wellbore applications are costly and interfere with well operations, as they require additional components and coolant lines that complicate heat transfer from the motor to the production fluid.
Innovation Solution
The implementation of external circulation tubes in communication with the motor's interior passages, allowing motor oil to flow through and transfer heat to the wellbore fluid, potentially aided by pumps or pressure differences, and enhanced by protective structures and recirculation baffles to increase heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external cooling devices with coolant lines are used, then heat transfer from motor to production fluid is improved, but device complexity and operational interference increase
Solution Approach 1:
The invention merges the cooling function with the existing motor housing structure by incorporating circulation tubes directly into the housing. This integration eliminates the need for separate external cooling devices and coolant lines, thereby reducing device complexity while maintaining effective heat transfer from the motor to the production fluid.
Solution Approach 2:
The system utilizes the existing production fluid flow through the wellbore as the cooling medium, eliminating the need for dedicated coolant systems. The motor housing with integrated circulation tubes allows the production fluid to directly cool the motor, reducing operational interference and simplifying the overall system.
2Reliability
If motor oil circulates through internal passages only, then lubrication is provided, but heat transfer rate to production fluid is insufficient
Solution Approach 1:
The invention extends the heat transfer path from two-dimensional internal passages to three-dimensional external circulation tubes that protrude into the production fluid flow. This dimensional extension significantly increases the heat transfer surface area and improves the rate at which heat is dissipated from the motor oil to the production fluid.
Solution Approach 2:
The circulation tubes are segmented into multiple separate tubes rather than a single passage, increasing the total surface area for heat transfer. Each tube acts as an independent heat transfer pathway, allowing more efficient dissipation of heat from the motor oil to the surrounding production fluid.
3Temperature
If heat transfer surface area is increased, then cooling efficiency is improved, but motor housing complexity increases
Solution Approach 1:
The motor housing is designed to serve multiple functions: it provides structural support, contains the motor components, and acts as a heat exchanger through integrated circulation tubes. This multi-functionality increases heat transfer surface area without proportionally increasing complexity, as the housing structure itself performs the cooling function.
Solution Approach 2:
The circulation tubes are nested within or integrated into the motor housing structure, with tubes positioned both internally and externally. This nesting approach maximizes heat transfer surface area while minimizing additional complexity, as the cooling structure is incorporated within the existing housing rather than added as a separate external system.
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 method enhances heat transfer from the motor to the surrounding wellbore fluid, prolonging motor life and reducing operational costs by utilizing existing fluid flow for cooling without additional external cooling devices.
Implementation Method 1
The lubricant absorbs heat from heat generating surfaces, such as surfaces experiencing friction, and from other hot spots within the motor
Implementation Method 2
As the oil circulates, it carries the heat from the hot spots to other cooler areas, where the heat is transferred to the cooler areas. Heat may be transferred through the exterior housing of the motor to the wellbore fluid in which the motor is submerged
Implementation Method 3
circulation tubes may be located externally to the motor. Each circulation tube is in communication with interior passages within the motor, in at least two places, such that motor oil flows through the circulation tube. As the motor oil flows through the tube, it transfers heat to the tube, which in turn passes the heat to the wellbore fluid in which the motor and the tubes are submerged
Data Source
AI summary
An electrical submersible pump motor has motor oil flowing through external circulation tubes for cooling the motor. A substantial portion of the exterior of each tube is submerged in and exposed to wellbore fluid. Heat is transferred from the motor to the motor oil, and then circulated through the external circulation tubes to conduct heat to the wellbore fluid. Internal or external motor oil pumps may be used to propel the motor oil through the circulation tubes. Guards or baffles may be used to protect the circulation tubes and to influence the flow of production fluid over the circulation tubes.