In-Situ ALD Coating for Downhole Tool Interior Passages
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Solution Overview
Problem
Downhole geological inspection tools face corrosion and electrical pathway shorting due to harsh environmental conditions, making it challenging to maintain effective coatings on large, hard-to-access surfaces like those within tool bodies.
Innovation Solution
The use of atomic layer deposition (ALD) process within the tool body itself, where reactants are alternately applied to specific passages through flow tubes, allowing for a controlled, vacuum-free coating of interior surfaces without altering the tool's design properties, using buffers to prevent reactant interaction and achieve a substantially holiday-free coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coating methods are used on downhole tools, then the tools can be protected against corrosion, but the coating process requires vacuum chambers that cannot accommodate large tool bodies and interior surfaces
Solution Approach 1:
The coating process is segmented into two distinct phases: (1) exterior coating using a vacuum chamber, and (2) interior coating using an in-situ ALD process within the tool body. This segmentation allows each method to be applied where it is most effective, resolving the contradiction between comprehensive protection and chamber size limitations.
Solution Approach 2:
The ALD coating system is nested within the downhole tool body itself, using the tool's own passages and cavities as the reaction chamber. This eliminates the need for a separate vacuum chamber for interior surfaces, as the coating process occurs inside the tool during manufacturing.
2Reliability
If ALD process is used to coat interior surfaces, then a durable protective coating can be applied, but the process requires precise control of reactant flow and timing
Solution Approach 1:
A buffer gas (such as nitrogen) is introduced as an intermediary between the aluminum-containing reactant and the oxygen-containing reactant. This buffer prevents premature reaction of the reactants in the gas phase and ensures they reach the surface in sequence, simplifying the flow control requirements while maintaining coating quality.
Solution Approach 2:
The ALD process uses periodic, sequential introduction of reactants and buffer gases in controlled cycles. Each cycle deposits a controlled thickness of coating material, and multiple cycles build up the desired coating thickness. This periodic action simplifies control by breaking down the complex coating process into repeatable, manageable steps.
3Manufacturing precision
If the tool body is heated to high temperatures for coating, then the coating adheres better, but the tool's design properties and material characteristics may be altered
Solution Approach 1:
The ALD process operates at lower temperatures (typically room temperature to 150°C) compared to traditional high-temperature coating methods. This parameter change in processing temperature allows the coating to adhere properly without altering the tool body's material properties or design characteristics.
Solution Approach 2:
The patent replaces mechanical/thermal coating methods (which require high heat and force) with a chemical vapor deposition process. This substitution allows coating at lower temperatures by using controlled chemical reactions on the surface, preserving the tool's material integrity while achieving durable adhesion.
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
This method provides a durable, corrosion-resistant coating that prevents chemical interaction and arcing, increases surface hardness, and reduces wear on tool components, enhancing tool longevity and performance.
Implementation Method 1
The use of atomic layer deposition (ALD) process within the tool body itself, where reactants are alternately applied to specific passages through flow tubes
Implementation Method 2
using buffers to prevent reactant interaction and achieve a substantially holiday-free coating
Data Source
AI summary
Apparatus and systems may operate to provide a first reactant as a gas that flows under reduced atmospheric pressure to interact with a surface, such as a tool body surface, the interaction confined to a passage within the tool body, wherein the passage includes the surface and extends without interruption from an entrance end of the passage to an exit end of the passage. Additional activity may include providing a second reactant as a gas under the reduced atmospheric pressure, subsequent to the first reactant, to interact with the surface of the tool body; and repeated provision of the first and second reactants until a selected coating thickness on the surface is formed. Additional apparatus, systems, and methods are disclosed.