Non-Radioactive Proppant Tracers for Fracture Stage Detection
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Solution Overview
Problem
Existing radioactive tracers for evaluating fracturing procedures suffer from uneven mixing issues, signal fluctuation, and environmental and health hazards, making it difficult to accurately detect and differentiate tracers in wellbores, especially in horizontal wells.
Innovation Solution
The use of multiple non-radioactive tracer-tagged proppants, such as gadolinium, boron, and samarium, in combination with a pulsed neutron capture logging tool to identify and distinguish between different stages of fracturing procedures by analyzing detector count rates and capture gamma ray spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If radioactive tracers are used to evaluate fracturing procedures, then tracer detection capability is provided, but health and safety hazards increase and environmental protection becomes more difficult
Solution Approach 1:
The patent replaces radioactive tracers with non-radioactive alternative tracers that do not pose health and safety hazards. These non-radioactive tracers achieve the same detection function through different physical principles (neutron capture cross-section differences rather than radiation emission), eliminating the harmful effects while maintaining tracer utility for fracture evaluation.
Solution Approach 2:
The patent substitutes the radioactive decay mechanism with a non-radioactive neutron capture mechanism. Instead of detecting radiation emission from radioactive isotopes, the system uses neutron capture cross-section differences of non-radioactive materials to generate detectable signals, thereby replacing a harmful physical mechanism with a safe alternative.
2Difficulty of detecting and measuring
If radioactive tracers are used in horizontal wellbores, then fracture evaluation is possible, but tracer mixing becomes uneven and signal accuracy decreases
Solution Approach 1:
The patent changes the physical parameters of the tracer system by switching from radioactive isotopes to non-radioactive materials with distinct neutron capture cross-sections. This parameter change allows the tracers to behave more predictably in horizontal wellbores, avoiding the settling and uneven mixing issues associated with radioactive tracers, thereby improving signal accuracy.
3Measurement precision
If multiple radioactive tracers are used to differentiate fracturing stages, then fracture stage identification is improved, but regulatory compliance becomes more complex
Solution Approach 1:
The patent eliminates the need for multiple radioactive tracers by using non-radioactive tracers with distinct neutron capture signatures. This approach maintains the ability to differentiate multiple fracture stages while significantly reducing regulatory compliance complexity, as non-radioactive materials do not require the same level of licensing, monitoring, and safety protocols as radioactive isotopes.
4Object-affected harmful factors
If non-radioactive tracers are used, then health and safety is improved, but tracer detection and differentiation capability becomes insufficient
Solution Approach 1:
The patent replaces the radiation detection mechanism with a neutron capture detection mechanism. Non-radioactive tracers with high neutron capture cross-sections (such as gadolinium, boron, or samarium compounds) are used, and the captured neutrons are detected through their characteristic gamma-ray emissions or other detectable signals, providing sufficient detection capability without health and safety hazards.
Solution Approach 2:
The patent changes the detection parameter from radiation emission intensity to neutron capture cross-section differences. By selecting non-radioactive materials with distinctly different neutron capture cross-sections, the system achieves adequate tracer differentiation capability through neutron capture measurements, overcoming the limitations of non-radioactive tracers in terms of detectability.
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 accurate detection and differentiation of multiple fracturing stages, improving the reliability of fracture evaluation and enhancing the efficiency of fracturing operations by reducing uncertainties and costs.
Implementation Method 1
measures capture gamma ray spectroscopy using a PNC logging tool and spectrally resolves the capture gamma rays emanating from the tagged proppant
Implementation Method 2
measures capture gamma ray spectroscopy using a PNC logging tool and spectrally resolves the capture gamma rays emanating from the tagged proppant from the capture gamma rays coming from other downhole elements
Data Source
Figure 1~2
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AI summary
A method for evaluating induced fractures in a wellbore includes obtaining a first set of data in a wellbore using a downhole logging tool. A first proppant is pumped into the wellbore, after the first set of data is captured. The first proppant includes a first tracer that is not radioactive. A second proppant is also pumped into the wellbore, after the first proppant is pumped into the wellbore. The second proppant includes a second tracer that is not radioactive, and the second tracer is different than the first tracer. A second set of data is obtained in the wellbore using the downhole tool after the first and second proppants are pumped into the wellbore. The first and second sets of data are compared.