X-ray Casing Imaging Tool for Corrosion Detection
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Solution Overview
Problem
Current methods for monitoring well casing integrity in the oil and gas industry lack the capability to produce complete, accurate, and reliable backscatter images of casings using x-rays, particularly in environments with non-optically clear fluids, and fail to create photograph-like two-dimensional images of the casing while the tool is axially moved through the wellbore.
Innovation Solution
An x-ray-based casing imaging tool with a combination of cylindrically located source collimators and a rotatable two-dimensional per-pixel collimated imaging detector array, which produces a conical x-ray beam and reduces attenuation, allowing for the creation of helical ribbon backscatter images of the casing by rotating the detector array azimuthally as the tool is conveyed through the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cameras are used to determine casing cylindricality and corrosion, then visual inspection capability is improved, but the method becomes inapplicable when wellbore fluids are not optically clear
Solution Approach 1:
The patent replaces optical cameras with an x-ray imaging system that uses electromagnetic radiation instead of visible light. The x-ray source and detector array capture backscattered x-rays from the casing, enabling imaging through opaque wellbore fluids without requiring optical clarity. This substitution of the imaging mechanism allows the system to function in environments where camera-based methods fail.
2Adaptability or versatility
If ultrasonic tools are used to image casing and external elements, then imaging capability in various fluid conditions is improved, but the method becomes model dependent requiring prior knowledge of well makeup
Solution Approach 1:
The patent replaces ultrasonic imaging with x-ray backscatter imaging. The x-ray method directly images the casing based on material density and atomic number differences, producing images that do not require acoustic modeling or prior knowledge of well construction. The system captures direct x-ray attenuation patterns from the casing wall, eliminating the need for complex acoustic models and preliminary well characterization.
Solution Approach 2:
The patent changes the physical parameter used for imaging from acoustic impedance (ultrasonic) to x-ray attenuation coefficient. By using x-rays with energies in the range of 100-500 keV, the system directly probes the electronic density and compositional structure of the casing material, providing images based on inherent material properties rather than requiring acoustic model matching or prior well knowledge.
3Use of energy by moving object
If conventional x-ray backscatter methods are used, then radiation penetration capability is improved, but the ability to produce complete and accurate backscatter images is insufficient
Solution Approach 1:
The patent divides the detector system into a two-dimensional array of individually collimated detector elements. Each detector element is equipped with its own collimator, allowing independent measurement of x-rays from specific angular directions. This segmentation of the detector array enables complete spatial sampling of backscattered x-rays across the entire casing circumference, producing accurate two-dimensional images that conventional single-detector methods cannot achieve.
Solution Approach 2:
The patent introduces collimators as intermediary components between the x-ray source and the detector array. These collimators shape and direct the x-ray beam, ensuring that each detector element receives x-rays only from its specific line of sight. This intermediary structure enables precise geometric control of the imaging process, allowing reconstruction of accurate two-dimensional casing images from the backscattered radiation patterns.
4Device complexity
If a non-padded concentrically-located borehole logging tool is used with collimators, then tool simplicity is improved, but the capability to produce reliable backscatter images is currently unavailable
Solution Approach 1:
The patent implements a segmented detector array where each detector element has its own collimator, arranged in a two-dimensional pattern around the x-ray source. This segmentation allows the simple non-padded concentric tool structure to capture complete angular information about backscattered x-rays, producing reliable two-dimensional images of the casing that maintain structural simplicity while achieving imaging reliability.
Solution Approach 2:
The patent transitions from one-dimensional or point-detector x-ray measurements to two-dimensional imaging by arranging collimated detector elements in a two-dimensional array. This dimensional expansion allows simultaneous measurement of backscattered x-rays from multiple angular positions, enabling reconstruction of complete two-dimensional casing images while maintaining the simplicity of the concentric non-padded tool structure.
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
Enables the production of high-quality, consolidated two-dimensional images of the well casing, capable of detecting corrosion, holes, cracks, and scale-buildup, with the option for machine learning analysis to enhance image quality and feature identification.
Implementation Method 1
an x-ray source; producing x-rays in a shaped output
Implementation Method 2
measuring the intensity of backscatter x-rays returning from the casing or tubing
Data Source
AI summary
An x-ray-based casing imaging tool, defined by a combination of source collimators, located cylindrically around an X-ray source and a rotatable two-dimensional per-pixel collimated imaging detector array, is provided, the tool including at least an x-ray source; a radiation shield to define the output form of produced x-rays; a direction controllable two-dimensional per-pixel collimated imaging detector array; an imaging window within the tool housing that reduces attenuation of x-rays passing through said tool housing; sonde-dependent electronics; and a plurality of tool logic electronics and PSUs. A method of using an x-ray-based casing imaging tool to determine the integrity of well casing or tubing is also provided, the method including at least: producing x-rays in a shaped output; measuring the intensity of backscatter x-rays returning from materials surrounding the wellbore; controlling two-dimensional per-pixel collimated imaging detector arrays; and converting image data from said detectors into consolidated images of the wellbore materials.