Degradable Plug for Downhole Tool Port Protection
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Solution Overview
Problem
Downhole tools are often rendered inoperable during wellbore cementing operations due to obstruction of their tool ports by cement composition and debris, and traditional burst disks are prone to failure and premature leaks, preventing fluid communication and rendering the tools unusable.
Innovation Solution
A degradable plug is used to prevent wellbore debris from entering the tool port, which degrades over time or in response to environmental conditions, allowing fluid communication between the downhole tool and the casing interior after the cementing operation is complete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a burst disk is used to prevent cement composition from entering the tool port, then the downhole tool is protected during cementing, but the burst disk is prone to failure and premature leaks, rendering the tool inoperable
Solution Approach 1:
The patent employs a disposable plug that is intentionally designed to be destroyed during the cementing operation. This plug is placed in the tool port to block cement entry, then deliberately destroyed by circulating destruction fluid (such as acid) to open the tool port for operation. The plug is consumed in the process, eliminating the reliability issues of reusable burst disks.
Solution Approach 2:
The plug is pre-installed in the tool port before cementing to provide immediate protection. The system is prepared in advance with the plug in place, and the destruction mechanism (acid circulation path) is pre-configured. This preliminary arrangement ensures protection during cementing while enabling subsequent operation without requiring complex activation procedures.
2Ease of operation
If the tool port is kept open for downhole tool operation, then the tool can function, but cement composition and debris will obstruct the tool port, rendering the tool inoperable
Solution Approach 1:
A disposable plug is used to temporarily block the tool port during cementing. This plug is inexpensive and intended to be destroyed rather than reused. After serving its protective function, it is eliminated by circulating destruction fluid, permanently opening the tool port for tool operation without risk of cement obstruction.
Solution Approach 2:
The plug is discarded after its protective function is complete. Rather than attempting to retrieve or reuse the plug, the system is designed to destroy it in place using circulation of destruction fluid. This discarding approach simplifies the system by eliminating the need for complex retrieval mechanisms while ensuring complete opening of the tool port.
3Reliability
If a burst disk is used to initiate fluid communication after cementing, then the tool port is protected during cementing, but the burst disk may fail to rupture in response to increased fluid pressure, rendering the tool inoperable
Solution Approach 1:
Instead of relying on a burst disk to rupture under pressure, the system uses a disposable plug that is intentionally destroyed by circulating destruction fluid. This active destruction mechanism is more reliable than passive pressure rupture, as it provides positive control over when the tool port opens while using a simple, inexpensive plug.
Solution Approach 2:
The patent replaces the mechanical burst disk rupture mechanism with a chemical/circulation-based destruction mechanism. Rather than relying on fluid pressure to mechanically rupture a disk, the system circulates destruction fluid (such as acid) to chemically or physically destroy the plug, providing more reliable and controllable initiation of fluid communication.
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 degradable plug effectively prevents tool port obstruction during cementing, ensuring the downhole tool can resume operation once the cementing process is finished, enhancing the reliability and longevity of downhole equipment.
Implementation Method 1
The degradable plug may degrade or dissolve after a predetermined period of time or following exposure to a particular wellbore environment, after which fluid communication between the interior of the casing mandrel and the downhole tool may be established
Data Source
AI summary
A casing mandrel includes a body having a first end and a second end, the first end being configured to be coupled to an upper portion of a casing string and the second end being configured to be coupled to a lower portion of the casing string, a downhole tool operatively coupled to an outer surface of the body, a tool port defined in the body and extending between the downhole tool and an interior of the body and thereby placing the downhole tool in fluid communication with the interior of the body, and at least one degradable plug disposed within the tool port to prevent wellbore debris from obstructing fluid communication between the interior and the downhole tool, wherein the degradable plug degrades over time.