Wellbore Depressurization Fracturing for Ductile Bedrock Cracking
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Solution Overview
Problem
Conventional hydraulic fracturing methods are ineffective in creating cracks in the ductile range of bedrock where supercritical fluids are present, as they rely on high-pressure injection, which is not applicable to this range.
Innovation Solution
A fracturing method involving a depressurization step using a depressurizing device to depressurize and boil high-temperature, high-pressure fluids, causing cracks in bedrock by exploiting thermal stress differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-pressure fracturing fluid injection is used, then cracks can be caused in brittle range bedrock, but this method is ineffective in ductile range bedrock where supercritical fluids are present
Solution Approach 1:
Instead of applying high pressure to create cracks (conventional method), the invention applies low pressure to allow the wellbore to collapse inward, creating compression fractures in the ductile bedrock. This inverted approach - using pressure reduction rather than pressure increase - enables effective fracturing in the ductile range where conventional high-pressure methods fail.
Solution Approach 2:
The invention changes the pressure parameter from high (conventional) to low (innovative), and changes the mechanical state from tensile (conventional) to compressive (innovative). By controlling the wellbore collapse under low pressure, the system generates compression fractures suitable for ductile bedrock, thereby adapting the fracturing mechanism to different rock mechanical properties.
2Productivity
If conventional hydraulic fracturing is applied to improve bedrock permeability, then underground resources can be collected effectively, but the method cannot be applied to ductile range bedrock
Solution Approach 1:
The invention inverts the conventional approach by using wellbore collapse under low pressure instead of high-pressure fluid injection. This creates compression fractures in ductile bedrock, enabling resource collection from supercritical fluid regions that were previously inaccessible to conventional hydraulic fracturing methods.
3Strength
If high-pressure fracturing is used to create cracks, then permeability improves in brittle range, but the method requires complex high-pressure equipment and has environmental impact
Solution Approach 1:
Instead of using complex high-pressure injection equipment, the invention uses simple low-pressure equipment to induce wellbore collapse. This inverted approach replaces complex high-pressure systems with simpler low-pressure systems, reducing equipment complexity while achieving effective fracturing in ductile bedrock.
Solution Approach 2:
The invention substitutes the mechanical high-pressure injection system with a low-pressure wellbore collapse system. By replacing the active high-pressure mechanical system with a passive low-pressure collapse mechanism, the system achieves fracturing with simpler equipment and reduced environmental impact.
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 method effectively creates cracks in ductile bedrock, improving permeability and enabling the collection of supercritical fluids without high-pressure equipment, reducing environmental impact and costs.
Implementation Method 1
a high-temperature and high-pressure fluid in a supercritical state or a subcritical state is depressurized and boiled
Implementation Method 2
bedrock is cooled quickly by the latent heat of vaporization during the depressurization and boiling
Implementation Method 3
it is possible to cause cracks in the bedrock by using the difference in thermal stress between the quickly cooled part and the other parts
Data Source
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AI summary
PROBLEM TO BE SOLVED: To provide a fracturing method that makes it possible to cause cracks even in the ductile range of bedrock. MEANS TO SOLVE THE PROBLEM: The fracturing method according to the present invention is used to cause a crack in bedrock, and includes an installation step of installing, in a well 8 installed in the bedrock 9, a depressurizing device, which depressurizes the inside of the well 8, and a depressurization step of depressurizing the inside of the well 8, with the depressurizing device 1 installed in the installation step. The installation step includes installing, in the well 8, a connecting pipe 3, which is connected to the depressurizing device 1, and a packer 4, which is attached to the connecting pipe 3, and the depressurization step includes shutting off a gap between the well 8 and the connecting pipe 3, with the packer 4, and depressurizing a region in the well below the packer 4, with the depressurizing device 1.