NMR Drill Collar Axial Magnet Arrangement
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Solution Overview
Problem
Nuclear magnetic resonance (NMR) tools in drilling operations face a tradeoff between increasing component size for enhanced sensitivity and accuracy, and maintaining structural integrity and cost constraints, as larger components are often too sensitive to provide mechanical support, leading to reduced drill collar structural integrity and increased material costs.
Innovation Solution
The solution involves selecting and arranging materials and components within the drill collar to maximize sensitivity and accuracy while meeting structural and cost constraints, by using a central magnet surrounded by a booster magnet and positioning an antenna assembly between the axial sides, with end magnets enhancing the magnetic field strength without compromising the drill collar's structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of sensitive NMR components is increased to enhance sensitivity and accuracy, then NMR measurement performance is improved, but the structural integrity of the drill collar is compromised and material costs increase
Solution Approach 1:
The patent transitions from increasing lateral dimensions to extending the magnetic assembly axially. The magnetic assembly includes a central magnet with booster magnets positioned at opposite ends, creating an elongated configuration that enhances magnetic field strength without increasing the lateral cross-sectional area of the drill collar. This axial dimensionality change allows larger effective component size while maintaining structural integrity.
Solution Approach 2:
The magnetic assembly is nested within the drill collar structure. The central magnet is surrounded by booster magnets, and the entire magnetic assembly is positioned within the drill collar's interior volume. This nesting arrangement maximizes the use of available space while maintaining the structural integrity of the outer drill collar housing.
2Measurement precision
If the size of sensitive NMR components is increased to enhance sensitivity and accuracy, then NMR measurement performance is improved, but material costs increase
Solution Approach 1:
By extending the magnetic assembly axially rather than increasing lateral dimensions, the patent avoids the need for expensive lateral expansion of the drill collar. This dimensional strategy allows cost-effective construction by using standard drill collar outer diameters while achieving enhanced NMR performance through axial elongation of the magnetic component array.
3Measurement precision
If the lateral cross-sectional area of the drill collar is increased to accommodate larger NMR components, then NMR sensitivity is improved, but the drill collar becomes less structurally efficient and more expensive
Solution Approach 1:
The patent explicitly avoids increasing the lateral cross-sectional area of the drill collar. Instead, it achieves enhanced NMR sensitivity by extending the magnetic assembly axially within the existing lateral dimensions. The magnetic assembly spans a greater axial length with booster magnets positioned at the ends, providing improved sensitivity without additional lateral material usage.
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 approach enhances the sensitivity and accuracy of NMR tools while maintaining the structural integrity of the drill collar, allowing for cost-effective construction and improved magnetic field strength without increasing the lateral cross-sectional area, thus addressing the tradeoff between component size and structural support.
Implementation Method 1
magnets that generate a static magnetic field in adjacent subsurface materials
Implementation Method 2
coils or antennas that induce a radio frequency (RF) magnetic field in the adjacent subsurface materials
Data Source
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AI summary
In some aspects, a material for constructing a drill collar is selected based on a cost and a minimum thickness for a cross-sectional area of material that satisfies a structural constraint. An interior volume of the drill collar houses one or more downhole nuclear magnetic resonance (NMR) components based on its minimum thickness. A central magnet coupled to a booster magnetic element disposed in the interior volume. A first end magnet and a second end magnet are positioned in the interior volume proximate respective axial sides of the booster magnetic element, and an antenna assembly is positioned proximate to the interior volume, between the respective axial sides of the magnetic assembly and about at least a portion of the central magnet.