X-ray Cement Evaluation Tool for Micro-annulus Detection
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Solution Overview
Problem
Current methods for determining cement bond quality between casing and cement in oil & gas wells are inadequate, as they fail to accurately detect micro-annuli and delamination, leading to potential fluid-migration paths and loss of zonal isolation, and existing x-ray technologies cannot compare anticipated density profiles to measured interfaces.
Innovation Solution
An x-ray-based cement evaluation tool using a conical x-ray beam with per-pixel parallel-hole collimators and arrayed pixelated detectors measures returning photons as a function of radial and axial offset, remapping intensity to determine the presence of annuli between the casing and cement, enabling discrimination of depth and detection of micro-annuli.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic tools are used to determine cement bond quality, then the ability to verify hydraulic seal is improved, but the measurement accuracy deteriorates due to treatment of annular material as single isotropic homogenous volume
Solution Approach 1:
The patent segments the annular material into multiple depth zones using a conical x-ray beam that illuminates different radial depths at different axial positions. This allows the system to treat the annular material not as a single homogenous volume, but as multiple distinct depth regions, each with its own density characteristics. The conical beam geometry naturally creates depth-dependent sampling zones that can be independently analyzed for cement bond quality.
Solution Approach 2:
The patent transitions from traditional ultrasonic two-dimensional surface measurement to a three-dimensional volumetric analysis using conical x-ray beams. The conical beam geometry creates a depth-dependent measurement zone that provides radial and axial resolution simultaneously, enabling the system to distinguish between different depth zones within the annular material and assess cement bond quality at multiple depths rather than treating the entire annulus as a single layer.
2Measurement precision
If current x-ray tools are used to produce three dimensional voxelated map of cement, then the cement mass inspection is improved, but the ability to determine micro-annulus existence deteriorates
Solution Approach 1:
The patent applies local quality analysis by measuring x-ray backscatter intensity at specific radial and axial positions within the annulus. By comparing the measured backscatter intensity at the cement-casing interface against the anticipated density profile, the system can locally identify variations in material density that indicate the presence of micro-annuli. This localized intensity comparison enables detection of small gaps and delamination at specific depths rather than providing only a bulk three-dimensional map.
Solution Approach 2:
The patent replaces traditional mechanical ultrasonic inspection methods with x-ray backscatter measurement. The x-ray technique measures density variations through backscatter intensity, which can detect micro-annuli and delamination by comparing measured profiles against anticipated density profiles. This substitution of mechanical measurement with radiological measurement enables better detection of micro-structural features that ultrasonic tools cannot resolve.
3Adaptability or versatility
If acoustic/ultra-sound tools are run within the same tool-string as x-ray tools, then both cement bond inspection and cement mass inspection can be performed, but the device complexity increases
Solution Approach 1:
The patent creates a universal inspection tool by integrating both x-ray source/detector systems and acoustic/ultrasonic measurement capabilities into a single tool-string. The x-ray subsystem provides cement mass and micro-annulus detection through backscatter intensity measurement, while the acoustic subsystem provides cement bond verification. This multi-functional design allows a single tool to perform both density-based and bond-based inspection, eliminating the need for separate tool runs and reducing overall operational complexity despite the increased technical complexity of the integrated system.
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 determines cement bond integrity by producing two-dimensional x-ray backscatter images that can identify micro-annuli and delamination, providing accurate zonal isolation assessment without direct physical contact with the casing.
Implementation Method 1
producing x-rays in a conical beam to illuminate a well casing
Implementation Method 2
measuring returning photons as a function of radial and axial offset
Data Source
AI summary
An x-ray-based cement evaluation tool for determining whether a cement bond exists between the casing and cement of a cemented borehole is provided, the tool including at least: an internal length comprising a sonde section, wherein said sonde section further comprises an x-ray source; a radiation shield for radiation measuring detectors; arrayed pixelated detectors; sonde-dependent electronics; and a plurality of tool logic electronics and PSUs. A method of using an x-ray-based cement evaluation tool for measuring a cement bond between a casing and the cement of a cemented borehole is also provided, the method including: producing x-ray in a conical beam to illuminate a well casing; measurement of the returning photons as a function of radial and axial offset; remapping the intensity of returning photons to a geometric response within the casing and cement; and determining whether an annulus is present between the casing and cement.