Downhole Tool Assemblies With Sliding Sleeves for Core Extraction
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Solution Overview
Problem
The challenge of efficiently extracting cores from deep boreholes is exacerbated by the difficulty in engaging and removing the downhole tool due to mud and debris, leading to issues with standardised core barrel assemblies, particularly in triple-tube configurations.
Innovation Solution
A downhole tool assembly with sliding sleeves and a core ejection piston that inhibit radial and axial movement of split tubes, allowing for fluid flow and facilitating core extraction by sealing and directing fluid to expel the core, combined with a housing assembly for mounting the tool to various core barrel sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a triple-tube core barrel assembly is used with standardised sizes, then core extraction capability is improved, but the difficulty of engaging and removing the downhole tool increases due to mud and debris accumulation
Solution Approach 1:
The core barrel assembly is segmented into multiple functional components: outer tube, inner tube, pair of split tubes, and downhole tool assembly with sleeves. This segmentation allows independent movement and function of each component, enabling the split tubes to be restrained while the inner tube moves for core ejection.
Solution Approach 2:
The sleeves act as intermediary components between the split tubes and the downhole tool. They slidingly engage the split tubes to inhibit radial movement while allowing the downhole tool to function, and they can be easily removed to facilitate tool retrieval without dealing with mud-covered surfaces.
2Productivity
If the inner tube is made axially movable for core retrieval, then core ejection capability is improved, but radial movement of split tubes may occur causing tube overlap
Solution Approach 1:
The assembly is divided into axially movable components (inner tube) and radially restrained components (split tubes with sleeves). This segmentation allows the inner tube to move axially for core ejection while the split tubes remain radially stable due to the restraining sleeves.
Solution Approach 2:
The sleeves serve as intermediary restraints between the split tubes and the bore, preventing radial movement and tube overlap while allowing the inner tube to move axially for core ejection. The sleeves can be removed to facilitate core removal.
3Reliability
If the downhole tool is threadedly engaged with the core barrel, then secure mounting is achieved, but retrieval difficulty increases when mud and debris are present
Solution Approach 1:
The downhole tool assembly is segmented into the tool itself and the sleeves that engage the split tubes. This allows the sleeves to remain in place during operation for secure mounting, but be easily removed for retrieval without dealing with threaded connections covered in mud.
Solution Approach 2:
The sleeves act as intermediary components that provide secure engagement during operation through their sliding fit on the split tubes, but can be easily removed to facilitate tool retrieval. They transfer the engagement function from difficult-to-remove threaded connections to easily removable sliding fits.
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 enhances core extraction efficiency by preventing tube overlap and enabling reliable data acquisition during drilling, while accommodating different core barrel dimensions, thus improving the operational reliability and ease of core retrieval.
Implementation Method 1
pumping fluid into the inner tube and against the plug. This causes the plug and/or piston to urge against and push the split tubes and core out of the core barrel
Data Source
AI summary
Downhole tool assembly (10) for mounting to a core barrel assembly (12) including a core tube (14) and a pair of split tubes (16). The downhole tool assembly (10) includes a downhole tool (18) and at least one sleeve (20) dimensioned to slidingly engage the split tubes (16) to inhibit radial movement of the split tubes (16) and receive and retain the downhole tool (18) coaxially with the core tube (14). Core ejection pistons (72), and methods for extracting a core from bedrock are also disclosed. A housing assembly (120) for a downhole tool, downhole assemblies (180, 200), and methods of assembling such assemblies are also disclosed.