Microwave Heating for Microcrack Core Manufacturing

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Solution Overview

Problem

Current methods for manufacturing big-model low-permeability microcrack cores are complex, costly, and fail to accurately replicate the random patterns of microcracks in reservoir strata, limiting their practicality in simulating oil and gas reservoir development.

Innovation Solution

A method involving baking stones with a thin oil film, mixing with quartz sand and cement, and applying confining pressure to create a cement sample with randomly distributed microcracks, allowing for control over permeability and porosity, using readily available and inexpensive materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If traditional heating methods are used to generate microcracks, then microcracks can be formed, but the heating is uneven and heat energy transmission is slow

Engineering Contradiction:
Improveheating uniformityVSAvoidheat energy transmission speed
Core Design Contradiction:
TemperatureVSSpeed

Solution Approach 1:

The patent replaces traditional thermal heating methods with microwave heating technology. Microwaves directly energize water molecules within the rock core material, generating heat internally and uniformly throughout the sample volume rather than conducting heat from the surface inward. This substitution of heating mechanism resolves both the uneven heating and slow heat transmission problems of traditional methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If microwave heating method is used to generate microcracks, then heating uniformity and speed are improved, but radiation security problems occur if improperly used

Engineering Contradiction:
Improveheating uniformityVSAvoidradiation security
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent carefully controls microwave heating parameters including power level, heating duration, and frequency to achieve optimal microcrack generation while maintaining safety. By adjusting these parameters, the system generates sufficient thermal energy to create realistic microcracks without exceeding safety thresholds that would cause radiation hazards.

Inventive Principle:
Principle #35Parameter changes

3Shape

If uniform splitting method is used to stimulate microcracks, then the core can be divided into two equal parts, but the crack surface is straight and smooth and does not comply with actual microcrack patterns

Engineering Contradiction:
Improvecore divisionVSAvoidmicrocrack pattern realism
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical splitting methods with microwave-induced thermal heating. The microwaves heat the core material internally, causing differential thermal expansion and stress that naturally fractures the material along irregular paths resembling authentic microcracks. This produces realistic crack surfaces with varying orientations and morphologies rather than straight, uniform splits.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Length of moving object

If sand wire cutting method is used to control crack width, then the crack width can be controlled by adjusting sand wire thickness, but the crack surface pattern does not comply with actual pattern

Engineering Contradiction:
Improvecrack width controlVSAvoidcrack surface pattern
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical sand wire cutting method with microwave thermal heating. The microwaves penetrate the core and heat it throughout, creating internal thermal stresses that cause the material to fracture naturally. This process controls crack development through thermal physics rather than mechanical cutting, producing realistic crack patterns while still achieving width control through parameter adjustment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

5Quantity of substance

If triaxial compression method is used to generate multiple cracks, then multiple microcracks can be formed, but many devices are required and the operation method is complicated

Engineering Contradiction:
Improvenumber of microcracksVSAvoidnumber of devices
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent replaces the complex triaxial compression apparatus with a microwave heating system. The microwave generator produces electromagnetic radiation that penetrates the core sample and heats it uniformly throughout. This single device accomplishes what previously required multiple mechanical components and complex loading systems, significantly simplifying the experimental setup while generating multiple realistic microcracks.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

6Quantity of substance

If edible oatmeal is used to stimulate microcracks in cement samples, then microcracks can be formed, but the pattern is relatively simplex

Engineering Contradiction:
Improvemicrocrack formationVSAvoidmicrocrack pattern complexity
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent replaces the edible oatmeal inclusion method with microwave thermal heating. Instead of relying on physical inclusions to create simple crack patterns, the microwaves heat the cement matrix internally, generating thermal stresses that produce complex, realistic microcrack networks. This eliminates the need for artificial inclusions and creates naturally occurring fracture patterns.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical 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

This method enables the cost-effective and simple production of large-scale cores with varied microcrack patterns, effectively simulating the permeability and porosity of carbonate rocks and sandstones, enhancing the realism of oil and gas reservoir simulation experiments.

Implementation Method 1

the microwave heating method can generate the problem of radiation security if it is improperly used

Methodology Applied
Scientific EffectMicrowave heating: Dielectric Heating

Data Source

PatentUS10364184B2Manufacturing method of big-model low-permeability microcrack core
Publication Date: 2019.07.30 SOUTHWEST PETROLEUM UNIV

AI summary

A manufacturing method of a big-model low-permeability microcrack core includes: (1) determining the size of a microcrack core to be manufactured; (2) placing stones in a baking oven to bake for 24h under 120° C., placing the stones into a mixer, mixing and spraying oil, enabling the oil to seep into the stone, evenly forming a thin oil film on stone's surface; (3) mixing the oil sprayed stone with quartz sand and cement, adding water to mix evenly to obtain cement paste; (4) spreading butter on core mold's inner surface to form a thin butter film, pouring the cement paste into the core mold to obtain a cement sample; (5) loading confining pressure outside the core according to the requirements of porosity and permeability of the mold to adjust a pore permeability value; (6) obtaining the big-model core with microcrack after the cement sample is dried and formed.