Torque Converter Startup for Electrical Submersible Pumps
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Solution Overview
Problem
Electrical submersible pumps experience high-pressure drawdown during startup, leading to potential damage to downhole completion equipment such as sand screens, especially when using fixed-speed drives, and mechanical erosion when using variable-speed drives.
Innovation Solution
Incorporating a torque converter between the motor and discharge pump to gradually transfer rotational force, using a conversion fluid to create a vortex that incrementally ramps up the pump's speed, thereby reducing sudden pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed-speed drive is used to power the electrical submersible pump, then the pump provides consistent artificial lift, but severe high-pressure drawdown occurs during pump initiation that may damage downhole completion equipment
Solution Approach 1:
A torque converter is introduced as an intermediary device between the fixed-speed motor and the pump. The torque converter includes a motor-driven impeller that generates a fluid vortex, which then drives a pump-connected turbine. This fluid-mediated transmission system gradually transfers rotational energy to the pump, enabling smooth acceleration from zero speed while maintaining consistent ultimate lift capacity, thereby eliminating high-pressure drawdown spikes that would otherwise damage sand screens and completion equipment
Solution Approach 2:
The torque converter utilizes hydraulic principles by filling a sealed housing with conversion fluid. The motor impeller accelerates this fluid to create a rotating vortex, and the fluid's kinetic energy is transferred to the pump turbine. This hydraulic energy transmission mechanism provides smooth, progressive pump startup by allowing the pump to accelerate gradually with the fluid vortex rather than experiencing sudden mechanical torque application, thus preventing pressure drawdown damage
2Object-affected harmful factors
If a variable-speed drive is used to smoothly start the pump, then high-pressure drawdown is reduced, but mechanical erosion and damage occur to the discharge pump due to incompatible frequencies
Solution Approach 1:
The torque converter replaces electrical variable-speed control with hydraulic torque multiplication. The fixed-speed motor drives the impeller at constant speed, but the fluid vortex development and turbine response characteristics naturally provide smooth pump acceleration. This hydraulic approach eliminates the need for variable frequency drives that operate outside the pump's optimal operational curve, thereby preventing mechanical erosion and discharge pump damage while still achieving drawdown reduction
Solution Approach 2:
The invention substitutes the electrical control system (variable-speed drive) with a mechanical-hydraulic transmission system (torque converter). Instead of using electrical frequency variation to control pump speed, the system uses a fixed-speed motor coupled with a fluid coupling that mechanically provides smooth torque transfer. This substitution eliminates the harmful effects of incompatible operating frequencies on the discharge pump while maintaining the benefit of reduced pressure drawdown
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
The torque converter enables smooth-starting of the electrical submersible pump, minimizing damage to downhole components by gradually increasing pumping speed and maintaining pressure balance, thus preserving the integrity of sand screens and reducing mechanical stress.
Implementation Method 1
a motor-side rotor mated to an end of the motor shaft and operable generate a vortex of the conversion fluid within the hollow body when the motor shaft is provided with a torque
Implementation Method 2
a pump-side rotor mated to an end of the pump shaft and rotatable as the vortex impinges on the pump-side rotor, and thereby providing a torque to the pump shaft
Data Source
AI summary
An electrical submersible pump system for preventing high-pressure drawdown while starting includes a fixed-speed drive, hermetically-sealed motor including a motor shaft extending therefrom, a discharge pump including a pump shaft extending therefrom, and a torque converter interposing the motor and the pump. The torque converter includes a hollow body filled with a conversion fluid, a motor-side rotor mated to an end of the motor shaft and operable generate a vortex of the conversion fluid within the hollow body when the motor shaft is provided with a torque, and a pump-side rotor mated to an end of the pump shaft and rotatable as the vortex impinges on the pump-side rotor, and thereby providing a torque to the pump shaft to operate the discharge pump.