Downhole Casing Sting Injection With Check-Valve Annulus Sealing
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Solution Overview
Problem
Existing downhole tools for sealing off the space between a borehole wall and its casing suffer from issues such as the need for tensile force to withdraw the punch, risk of sealant backflow, and insufficient sealing, leading to potential leaks in the annulus.
Innovation Solution
A downhole tool with a sting that perforates the casing wall and injects sealant using a check valve to prevent backflow, allowing the sealant to cure without losing casing integrity, and the sting's distal end is left behind to ensure a secure seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a punch is forced through the casing wall to create a perforation for injecting sealing material, then the sealing material can be injected into the annulus, but the punch requires tensile force to be withdrawn and may break under stress
Solution Approach 1:
The tool is divided into separate functional components: the punch (perforating element) and the inject device (sealing material delivery system). This segmentation allows the punch to be withdrawn independently after serving its perforation function, eliminating the need for tensile force to pull it back through the casing wall.
Solution Approach 2:
The punch function is extracted from the injection system. The punch creates the perforation and then can be removed, while the injection device remains in place to deliver sealing material through the perforation. This separates the perforation function from the sealing function, resolving the contradiction between easy withdrawal and structural strength.
2Productivity
If the punch is drawn back into the casing before the sealing material cures, then the sealing material can be injected, but the seal may be insufficient and the sealing material may flow back into the casing
Solution Approach 1:
The punch creates the perforation in advance before the sealing material is injected. This preliminary perforation action allows the sealing material to be introduced immediately through a pre-established path, enabling rapid injection while ensuring the perforation is ready to accept the material without requiring the punch to be repositioned during curing.
Solution Approach 2:
The perforation acts as an intermediary structure between the injection device and the annulus. It provides a controlled pathway that guides the sealing material from the injection device directly into the annulus, preventing backflow and ensuring reliable sealing while allowing rapid injection through the pre-created opening.
3Ease of operation
If a screw of small section is used to hold the punch in place, then the punch can be secured in the casing perforation, but the screw will break under tensile stress less than required to withdraw the punch
Solution Approach 1:
The punch retention function is extracted from the injection system. Instead of using a weak screw that could break, the punch is held in place by the structural integrity of the casing wall itself and the geometry of the perforation, eliminating the need for a separate retention mechanism that would be prone to failure.
Solution Approach 2:
The punch is designed as a disposable perforating element that creates its function and then can be removed without requiring strong retention mechanisms. The temporary holding during injection is sufficient, and the punch can be withdrawn after serving its purpose, avoiding the need for high-strength retention components.
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 tool effectively seals the annulus by minimizing leak paths and ensuring the sealant cures without backflow, providing a reliable and efficient sealing process.
Implementation Method 1
a check valve arranged in said fluid channel which allows fluid communication in a direction from within the tool housing to an exterior of the tool housing and which blocks fluid flow in an opposite direction
Implementation Method 2
a press device acting on the sting to force the sting in a radially outward direction from the tool housing away from the longitudinal axis
Data Source
AI summary
A downhole tool, which includes a tool housing having a longitudinal axis, is equipped with a sting for punching a hole in a casing wall and injecting a sealant through the hole. The tube has a fluid channel to establish fluid communication from within the tool housing to an exterior of the tool housing through the fluid channel. A press device acts on the sting to force the sting in a radially outward direction from the tool housing. A check valve is arranged in the fluid channel, which allows fluid communication in a direction from within the tool housing to an exterior of the tool housing and which blocks fluid flow in an opposite direction. In use, the sting can perforate a casing wall and the sealant can be injected into an annular space around the casing.