X-Ray Cement Evaluation for 3D Annulus Anomaly Mapping
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Solution Overview
Problem
Current methods for detecting anomalies in annular materials of single and dual casing string environments are inadequate, failing to accurately determine the radial and azimuthal position of anomalies, leading to potential fluid-migration paths and loss of zonal isolation, and lack the ability to discriminate various depths within the cement or annular material.
Innovation Solution
An x-ray based cement evaluation tool that uses a non-padded, concentrically-located borehole logging tool with a pseudo-conical x-ray beam and collimated detectors to measure density variations within the annular materials, providing a three-dimensional map of the annular materials to identify anomalies and ensure zonal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic tools are used to detect cement bond, then the presence of cement in the annulus can be determined, but the tools cannot discriminate various depths into the cement or annular material and cannot determine radial and azimuthal position of anomalies
Solution Approach 1:
The tool divides the annular region into multiple depth zones using a plurality of detectors positioned at different axial locations. Each detector measures density at a specific depth interval, enabling discrimination of various depths into the cement or annular material. This segmentation allows the system to identify which specific zone contains an anomaly rather than treating the annulus as a single volume.
Solution Approach 2:
The invention transitions from treating the annulus as a single isotropic volume to mapping density variations in three dimensions (radial, azimuthal, and axial directions). By positioning detectors at multiple axial locations and using x-ray attenuation measurements, the system creates a three-dimensional density map that reveals the radial and azimuthal position of anomalies within the annular region.
2Measurement precision
If a non-padded tool is used to measure through casing, then the tool can be centralized with the well casing, but prior art cannot discriminate signals from behind casings from annular materials
Solution Approach 1:
The tool uses a plurality of detectors positioned at different axial locations, each measuring density in a specific local zone of the annulus. This local measurement approach allows the system to distinguish between signals originating from behind the casing and signals from the annular materials by analyzing the spatial distribution of attenuation patterns across multiple measurement points.
Solution Approach 2:
The x-ray source and detector array serve as intermediaries that penetrate the casing and provide differential attenuation measurements. By measuring x-ray attenuation through both the casing and annular materials simultaneously, the system can distinguish between the two based on their different attenuation characteristics, enabling signal discrimination without requiring physical contact with the casing.
3Ease of operation
If ultrasonic tools treat the annulus as a single isotropic volume, then the measurement process is simplified, but inaccuracies occur when actual deviations from this ideal exist
Solution Approach 1:
Instead of treating the annulus as a single isotropic volume, the tool segments the measurement into multiple discrete zones using detectors at different axial positions. Each detector provides independent density measurements for its specific zone, allowing the system to detect local variations and deviations from uniformity without requiring complex corrections to a simplified model.
Solution Approach 2:
The system measures actual density values at multiple locations rather than assuming a uniform density throughout the annulus. By obtaining real density measurements from the x-ray attenuation data and using these actual parameters in the zonal isolation assessment, the system maintains measurement accuracy even when the annular material deviates from the ideal isotropic homogeneous model.
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 detects and maps density variations in annular materials, identifying potential fluid paths and ensuring well integrity by providing precise radial and azimuthal positioning of anomalies without direct contact with the well casings, enhancing zonal isolation and cement integrity.
Implementation Method 1
the tool uses x-rays to illuminate the formation surrounding a borehole and a plurality of detectors are used to directly measure the density of the cement annuli and any variations in density within
Implementation Method 2
a shortest-axial offset detector is configured to distribute incoming photons into energy classifications such that photoelectric measurements may be made
Data Source
AI summary
An x-ray based cement evaluation tool for measurement of the density of material volumes within single, dual and multiple-casing wellbore environments 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; sonde-dependent electronics; and a plurality of tool logic electronics and PSUs, wherein the tool uses x-rays to illuminate the formation surrounding a borehole and a plurality of detectors are used to directly measure the density of the cement annuli and any variations in density within. Detectors used to measure casing standoff such that other detector responses are compensated for tool stand-off and centralization; a plurality of reference detectors is used to monitor the output of the x-ray source, and a shortest-axial offset detector is configured to distribute incoming photons into energy classifications such that photoelectric measurements may be made.