Nuclear Density Tool for Behind Pipe Cement Bond Evaluation
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Solution Overview
Problem
The existing method for determining the depth to cut and pull pipes during a plug and abandon operation in oil and gas wells often involves a trial and error process, leading to increased costs and time due to uncertainty in identifying the cement bond, which is not accurately defined by standard methods.
Innovation Solution
A nuclear tool is used to emit gamma rays into the pipe and surrounding material, with detectors measuring count rates in high and low-energy ranges to determine the compositional equivalent of the material between the pipe and the subterranean formation, allowing for precise identification of the cutting depth to minimize frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard methods (cement bond log and ultrasonic device) are used to define the portion of pipe not bonded to cement, then the determination can be made with existing equipment, but the process involves trial and error leading to increased costs and time
Solution Approach 1:
The patent replaces mechanical/physical testing methods (ultrasonic devices, trial and error cutting) with nuclear physics-based measurement. A nuclear tool emits gamma rays that interact with materials behind the pipe, and detectors measure scattered radiation to identify cement bonds and material compositions accurately without physical trial and error.
Solution Approach 2:
The patent introduces a nuclear tool as an intermediary device between the operator and the pipe-cement system. This tool uses gamma ray emission and detection to provide indirect but accurate information about material composition and bonding, eliminating the need for direct mechanical testing or trial cutting.
2Ease of manufacture
If trial and error process is used to determine cutting depth, then equipment and existing methods can be utilized, but costs and time increase due to uncertainty
Solution Approach 1:
The patent replaces unreliable trial-and-error mechanical cutting with reliable nuclear physics-based measurement. Gamma ray interaction patterns provide definitive identification of cement bonds and material transitions, allowing precise determination of cutting depth without uncertainty or repeated attempts.
Solution Approach 2:
The patent implements a feedback mechanism where the nuclear tool continuously measures gamma ray scattering patterns as it moves along the pipe, providing real-time information about material composition and bonding status. This feedback allows operators to identify the exact cutting point with confidence based on detected changes in radiation scattering characteristics.
3Measurement precision
If nuclear tool with gamma ray emission and detection is used, then accurate material identification and cutting depth determination are achieved, but device complexity increases
Solution Approach 1:
The patent designs the nuclear tool to perform multiple functions: emitting gamma rays, detecting scattered radiation, identifying different material compositions (cement, mud, gas, liquid), determining cement bond status, and locating the cutting point. This multi-functionality consolidates what would otherwise require multiple separate tools and procedures into a single device.
Solution Approach 2:
The patent utilizes changes in gamma ray scattering parameters (intensity, energy spectrum) as materials are encountered. By measuring how gamma rays scatter differently through cement, mud, gas, and liquid, the tool identifies material compositions and bonding status through parameter analysis rather than requiring complex mechanical or chemical analysis systems.
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 more accurate and efficient determination of the cutting depth, reducing operational costs and time by identifying the compositional equivalent of materials, thereby enhancing the efficacy and efficiency of cut and pull operations.
Implementation Method 1
emitting gamma rays into the pipe and the material from a source of a nuclear tool disposed in the wellbore; detecting gamma radiation scattered back from the pipe and the material with a detector of the nuclear tool
Data Source
AI summary
In relation to a cut and pull operation, a nuclear tool may be used for evaluating the composition of materials located behind a pipe lining the wellbore. More specifically, a downhole method may include emitting gamma rays into the pipe and the material from a source of a nuclear tool disposed in the wellbore; detecting gamma radiation scattered back from the pipe and the material with a detector of the nuclear tool; determining a high-energy range and a low-energy range for the gamma radiation; measuring count rates of the gamma radiation in the high-energy range (CRH) and the low-energy range (CRL); performing an analysis of (1) the CRH relative to (2) the CRL; and determining a compositional equivalent for the material based on the analysis.