Soft Drive Mechanism for Submersible Progressive Cavity Pump
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Solution Overview
Problem
Electrical submersible progressive cavity pumps face catastrophic failures due to fluctuating speeds and loads from passing solids, liquids, and gases, particularly in deviated or horizontal wells, where conventional drive mechanisms are inadequate.
Innovation Solution
A soft drive mechanism, incorporating a lead or ball screw with Bellville washers and a slot arrangement, decouples the motor and gearbox from the progressive cavity pump, allowing for constant speed operation and absorption of torque spikes, thereby protecting the transmission from detrimental fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional electric submersible motor with gearbox is used to power the PCP in deviated or horizontal wells, then the pump can operate in challenging well conditions, but the transmission suffers from catastrophic failures due to fluctuating speeds and loads
Solution Approach 1:
The patent introduces a dynamic coupling mechanism between the motor and pump that allows the system to adapt to fluctuating loads and speeds. The coupling includes flexible elements and damping mechanisms that accommodate the eccentric motion and variable torque conditions in deviated wells, preventing rigid stress transmission that leads to catastrophic failures.
Solution Approach 2:
The patent employs an intermediary coupling device between the motor and pump that acts as a buffer against load fluctuations. This intermediary mechanism includes flexible couplings and damping elements that absorb torque spikes and speed variations, protecting the transmission system from catastrophic failures while maintaining operational adaptability.
2Length of moving object
If the motor rotates at 3,600 RPM to minimize its length and cost, then the motor size is reduced, but the pump cannot operate at its ideal lower speed
Solution Approach 1:
The patent implements a dynamic speed adaptation mechanism that allows the pump to operate at optimal speeds regardless of the motor's fixed high-speed rotation. The coupling system includes variable ratio transmission elements that dynamically adjust the speed ratio between motor and pump, enabling the pump to run at ideal lower speeds while the motor maintains its compact high-speed design.
3Device complexity
If a rigid coupling is used between the motor and pump, then the transmission is simple, but it cannot accommodate the eccentric motion of the pump
Solution Approach 1:
The patent utilizes flexible coupling elements and thin-film damping layers in the motor-pump interface. These flexible components accommodate the eccentric motion and misalignment inherent in progressive cavity pump operation, absorbing mechanical stresses while maintaining a relatively simple overall transmission structure.
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 solution enables the use of high-speed motors with minimized length and cost, ensuring continuous operation and reducing the risk of transmission failure, while maintaining efficient fluid flow and cooling, even in challenging well conditions.
Implementation Method 1
the soft drive comprises a lead or ball screw which reacts against a stack of Bellville washers and transmits drive to the pump through a slot arrangement
Implementation Method 2
the soft drive comprises a lead or ball screw which reacts against a stack of Bellville washers and transmits drive to the pump through a slot arrangement
Data Source
AI summary
An electric submersible progressive cavity pump assembly is disclosed, which includes an electric motor, a progressive cavity pump, a transmission rotatable by the motor, and a torque isolator coupled between the transmission and the progressive cavity pump, where the torque isolator includes resilient members which accommodate sudden changes in torque.