Inverted Shroud Charge Pump for ESP Gas Slug Management
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Solution Overview
Problem
Electric submersible pumps (ESPs) face operational challenges due to gas slugs, which can cause gas lock, disrupt fluid flow, and lead to rapid bearing wear, reducing operational life and increasing maintenance costs, especially in wells with low reservoir pressure or high gas/oil ratios.
Innovation Solution
Incorporating a charge pump assembly downstream of the fluid intake and an inverted shroud to accumulate liquid phase fluid, which is then drawn down during gas slugs, ensuring continuous liquid flow to the production pump, and extending the length and volume of the shroud and fluid reservoirs to sustain operation during gas slug events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ESP assembly is used without additional liquid accumulation mechanisms, then the device complexity is low, but the reliability deteriorates due to gas lock during gas slug events
Solution Approach 1:
The inverted shroud and charge pump assembly pre-accumulate liquid phase fluid in the annulus between the shroud and production tubing before gas slug events occur. This preliminary liquid reservoir ensures that when gas slugs arrive at the production pump, there is already liquid available to maintain proper pump operation and prevent gas lock, thereby improving reliability without requiring complex active control systems.
Solution Approach 2:
The inverted shroud acts as an intermediary component between the gas slug and the production pump. By positioning the shroud to extend above the gas separator and creating a liquid-filled annulus, it mediates the interaction between gas and pump, allowing gas to be separated and vented while maintaining liquid contact with the pump impeller, thus preventing gas lock and improving operational reliability.
2Duration of action of moving object
If the shroud and fluid reservoirs are extended to sustain operation during gas slugs, then the duration of action increases, but the volume and device complexity increase
Solution Approach 1:
Instead of increasing the vertical height of the shroud alone, the invention utilizes the annular dimension by extending the shroud radially outward to engage with the production tubing. This creates a three-dimensional liquid accumulation space in the annulus between the shroud and tubing, effectively increasing liquid storage capacity and operational duration during gas slugs without excessively increasing overall assembly length.
3Reliability
If the inverted shroud is positioned to extend above the gas separator, then the reliability improves by preventing gas lock, but the device complexity and installation difficulty increase
Solution Approach 1:
The inverted shroud is integrated with the charge pump assembly as a unified component rather than a separate attachment. The shroud forms part of the charge pump housing structure, merging the liquid accumulation function with the existing pump assembly. This integration simplifies manufacturing and installation by reducing the number of separate components and assembly steps, while still providing the reliability benefit of preventing gas lock.
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 solution allows ESPs to maintain normal operation during gas slug events, extending the time before gas fills the system and reducing the frequency of maintenance, thereby increasing operational efficiency and reducing downtime.
Implementation Method 1
an inverted shroud to accumulate liquid phase fluid
Implementation Method 2
charge pump assembly... ensuring continuous liquid flow to the production pump
Data Source
AI summary
An electric submersible pump (ESP) assembly. The ESP assembly comprises an electric motor; a seal section; a fluid intake; a charge pump assembly located downstream of the fluid intake and having an inlet in fluid communication with an outlet of the fluid intake, having a fluid mover coupled to a drive shaft, and having a fluid reservoir located downstream of the fluid mover; a gas separator located downstream of the charge pump assembly and having an inlet in fluid communication with an outlet of the charge pump assembly; an inverted shroud coupled at an upper end to the gas separator or to the charge pump assembly and coupled at a lower end to the ESP assembly below the fluid intake; and a production pump assembly located downstream of the gas separator and having an inlet in fluid communication with a liquid phase discharge port of the gas separator.