Rock Tensile Strength via Electromagnetic Heating
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Solution Overview
Problem
Traditional mechanical force testing methods for determining the tensile strength of rock samples are complex, unreliable, and often impractical for field measurements due to the need for large equipment and specific sample preparation, especially for tight rock materials like shale and sandstone.
Innovation Solution
A method using electromagnetic heating to increase the water content's temperature within rock samples, causing pore-water pressure to rise until the rock breaks, allowing for direct measurement of tensile strength through sensors, without requiring external force or complex sample preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical force testing methods are used to measure tensile strength of rock samples, then measurement can be performed, but the equipment required is large and complex and sample preparation is complicated
Solution Approach 1:
The patent replaces traditional mechanical force testing systems with an electromagnetic heating system. Instead of applying mechanical compressive force to induce tensile failure (Brazilian test) or direct pull force (pull test), the invention uses electromagnetic energy to heat the rock sample, causing thermal expansion and internal stress that leads to fracture. This substitution eliminates the need for large mechanical testing equipment and complex sample preparation while providing reliable tensile strength measurements.
Solution Approach 2:
The invention changes the physical parameter used for testing from mechanical force to temperature. By controlling the temperature increase of the rock sample through electromagnetic heating and monitoring the point of fracture, the method determines tensile strength without requiring mechanical loading equipment. This parameter change simplifies the testing apparatus while maintaining measurement accuracy.
2Measurement precision
If traditional mechanical force testing methods are used, then tensile strength can be determined, but the procedures are complex and results are often unreliable
Solution Approach 1:
The patent replaces traditional mechanical force testing systems with an electromagnetic heating system. Instead of applying mechanical compressive force to induce tensile failure (Brazilian test) or direct pull force (pull test), the invention uses electromagnetic energy to heat the rock sample, causing thermal expansion and internal stress that leads to fracture. This substitution eliminates the need for large mechanical testing equipment and complex sample preparation while providing reliable tensile strength measurements.
Solution Approach 2:
The rock sample itself serves as the heating medium through its water content. The electromagnetic energy heats the water within the rock pores, which then transfers heat to the rock matrix, causing uniform thermal expansion and internal stress. This self-heating mechanism eliminates the need for external heating equipment and complex test setup procedures, improving both reliability and simplicity.
3Measurement precision
If traditional mechanical force testing methods are used, then tensile strength measurement is possible, but large instruments and complex procedures are required making field measurement impractical
Solution Approach 1:
The patent replaces traditional mechanical force testing systems with an electromagnetic heating system. Instead of applying mechanical compressive force to induce tensile failure (Brazilian test) or direct pull force (pull test), the invention uses electromagnetic energy to heat the rock sample, causing thermal expansion and internal stress that leads to fracture. This substitution eliminates the need for large mechanical testing equipment and complex sample preparation while providing reliable tensile strength measurements.
Solution Approach 2:
The electromagnetic heating system serves multiple functions: it heats the rock sample, monitors temperature increase, and can detect fracture points through changes in electromagnetic properties. This multi-functionality consolidates what would otherwise require separate mechanical testing equipment, sample preparation facilities, and measurement instruments into a single portable system suitable for field operations.
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 direct, reliable, and efficient measurement of tensile strength for rock samples, including tight rocks, using electromagnetic heating to simulate hydraulic fracturing conditions, offering more accurate and practical field measurements.
Implementation Method 1
heating the rock sample with electromagnetic energy such that the electromagnetic energy heats the water content in the rock sample from an initial temperature
Implementation Method 2
heating the water content causes a pore-water pressure of the rock sample to increase
Data Source
AI summary
A method for determining the tensile strength of a rock sample comprising the steps of obtaining the rock sample, measuring a water content of the rock sample through a water measurement method, determining a matrix bulk modulus of the rock sample, wherein the matrix bulk modulus is determined through a matrix modulus method, heating the rock sample with electromagnetic energy such that the electromagnetic energy heats the water content in the rock sample from an initial temperature, wherein heating the water content causes a pore-water pressure of the rock sample to increase, detecting a break in the rock sample with a sensor, wherein the increase in the pore-water pressure causes the rock sample to break, wherein the break occurs at a break time, at a break temperature; and calculating the pore-water pressure through the water content, the matrix bulk modulus, and the break temperature of the water content.