Downhole Tool Fluid Circulation for In-Situ Replacement
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Solution Overview
Problem
Current electrical submersible pump systems in oil and gas wells face issues with motor oil degradation and contamination over time due to lack of maintenance and inability to replace fluids downhole, leading to reduced performance and potential need for artificial lift mechanisms.
Innovation Solution
A system and method for circulating tool fluids from a surface reservoir to replace and flush fluids in downhole tools, including a tool fluid source line and return line extending through a wellhead spool assembly, allowing for in-situ fluid replacement and sampling without retrieving the tool, thereby maintaining fluid quality and reducing the need for artificial lift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor oil is used in downhole motors, then lubrication and heat transfer are provided, but the motor oil degrades over time due to temperature and contaminants
Solution Approach 1:
The system enables discarding degraded motor oil and recovering fresh motor oil by establishing a circulation pathway from the downhole motor to the surface and back. The motor oil is pumped from the motor, transported to the surface through a conduit, and replaced with fresh motor oil, allowing continuous recovery and replacement of the lubricant without abandoning the downhole motor.
Solution Approach 2:
The system maintains continuous useful action by establishing an ongoing circulation and replacement cycle for motor oil. The motor oil continuously flows from the motor to the surface and fresh motor oil continuously replaces it, ensuring uninterrupted lubrication and cooling functions throughout the operational life of the downhole motor.
2Productivity
If electrical submersible pumps are installed for artificial lift, then oil and gas production is maintained, but the motor oil cannot be replaced downhole
Solution Approach 1:
The system introduces an intermediary circulation system consisting of a conduit, pump, and valve assembly that mediates between the downhole motor and the surface motor oil supply. This intermediary system enables fluid replacement without requiring retrieval of the downhole motor or disruption of hydrocarbon production, bridging the gap between production continuity and maintenance capability.
3Reliability
If motor oil is contained in a closed system, then leakage is minimized, but maintenance and fluid replacement become impossible
Solution Approach 1:
The system transforms the static closed system into a dynamic open system by introducing a pump and valve assembly that enables controlled fluid circulation. The motor oil can now dynamically flow from the downhole motor to the surface and fresh motor oil can dynamically replace it, converting the system from a fixed closed state to a flexible open state that allows maintenance while maintaining operational reliability.
4Duration of action of stationary object
If the electrical submersible pump operates for several years, then production is sustained, but the motor oil degrades due to lack of maintenance
Solution Approach 1:
The system enables self-service maintenance by allowing the motor oil to be pumped out and replaced without requiring retrieval of the downhole motor or intervention at the well site. The motor oil serves itself by being continuously circulated and replaced through the automated circulation system, eliminating the need for external maintenance operations.
Data Source
AI summary
An assembly for circulating tool fluid of a downhole tool includes a tool fluid source line extending into a subterranean well from a wellhead spool assembly to the downhole tool. A tool fluid return line extends out of the subterranean well from the downhole tool to the wellhead spool assembly. A tool fluid reservoir is located at a surface outside of the subterranean well. The tool fluid source line is in one way fluid communication with the tool fluid reservoir and the tool fluid is free of fluid communication with wellbore fluids.