Pumpdown Relief Valve for Downhole Tool Pressure Control
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Solution Overview
Problem
During pumpdown operations in horizontal wells, downhole tools experience rapid accelerations and decelerations due to changes in casing pipe diameter or downhole obstructions, leading to increased hydraulic pressure and cable tension, which can result in the tool being severed from the line, as existing control methods are delayed and insufficient in responding to these changes.
Innovation Solution
Incorporation of a pumpdown relief valve in the downhole tool that is responsive to differential fluid pressure changes, allowing fluid to bypass the wellbore isolation device or elastomeric external flange when pressure exceeds a threshold, thereby regulating hydraulic forces and reducing the risk of tool separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface pumps or drum spool rate are controlled to mitigate cable tension, then cable tension can be reduced, but the response is delayed by several seconds due to propagation delay and mechanical system response time
Solution Approach 1:
A downhole pressure regulator is introduced as an intermediary device located at the downhole tool to locally regulate hydraulic pressure. This mediator acts between the hydraulic system and the downhole tool, providing immediate pressure control without requiring surface system adjustments, thus eliminating the several-second delay inherent in surface-based control systems.
Solution Approach 2:
The patent replaces the mechanical surface-based pressure control system with a downhole electronic pressure regulation system. The downhole pressure regulator uses electronic sensors and actuators to detect and respond to pressure changes instantaneously, substituting the slow mechanical response of surface pumps and drum spooling with a faster electronic control mechanism located at the source of the problem.
2Speed
If hydraulic pressure is increased to convey the downhole tool, then the tool can be pumped down the wellbore, but rapid variations in hydraulic pressure can result in the tool being severed from the line
Solution Approach 1:
The downhole pressure regulator is configured to anticipate and prevent rapid pressure variations before they can cause tool severance. By continuously monitoring hydraulic pressure and proactively adjusting the regulator setting, the system takes preliminary action to smooth out pressure fluctuations that would otherwise occur when the tool encounters obstructions or changes in the wellbore geometry.
Solution Approach 2:
The pressure regulator acts as a cushioning mechanism that absorbs and dampens rapid hydraulic pressure variations. When the tool encounters downhole obstructions or changes in casing diameter, the regulator provides beforehand cushioning by regulating pressure spikes, preventing the extreme pressure variations that would otherwise transmit forces capable of severing the tool from the line.
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 pumpdown relief valve provides near-immediate pressure relief, reducing the risk of tool separation and maintaining control over hydraulic forces, even in the presence of downhole obstructions, by responding to pressure changes in milliseconds rather than seconds.
Implementation Method 1
a pumpdown relief valve that is responsive to changes in differential fluid pressure along a downhole tool and that allows fluid to bypass the downhole tool
Data Source
AI summary
This disclosure relates generally to downhole tools and, more particularly, embodiments related to incorporation of a pumpdown relief valve into a downhole tool that is responsive to changes in differential fluid pressure along a downhole tool. Disclosed is a system for pumpdown regulation in a wellbore. The system may include a downhole tool having a tool body with a tool head that is attachable to a line, the line being attached to a point at a surface of the wellbore. The system may further include a pumpdown relief valve coupled to the tool body that is operable to allow fluid to bypass the downhole tool in direct response to a differential fluid pressure across a length of the downhole tool.