CO2 Foam Fracturing Fluid Double Interface Layers
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Solution Overview
Problem
Conventional fracturing fluids used in shale gas production face issues such as high water consumption, damage to shale reservoirs, low flow-back rates, and environmental concerns due to water-based systems, which hinder efficient shale gas development, especially in water-scarce regions and damage the formation matrix.
Innovation Solution
A foam fracturing fluid with double interface layers is developed, comprising a liquid CO2 phase, a gas phase of phlogisticated air, and a nano-enhancer, where the liquid CO2 phase is stabilized by gas-soluble foaming agents and the nano-enhancer, reducing water content and enhancing stability, allowing for low-damage fracturing with improved flow-back and reduced waiting time for gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water-based fracturing fluid is used, then the fracturing operation can be performed, but water consumption is huge and causes environmental pollution
Solution Approach 1:
The patent changes the fundamental composition parameter of the fracturing fluid from water-based to CO2-based system. The fluid comprises liquid CO2 as the primary component (65-85% by volume), replacing water entirely. This parameter change eliminates water consumption issues and environmental pollution while maintaining fracturing functionality through CO2's unique properties including phase change capability and solubility characteristics.
Solution Approach 2:
The patent utilizes CO2 phase transitions (liquid to gas) as the core mechanism for fracturing fluid operation. Liquid CO2 is injected under pressure, then undergoes phase transition to gas phase in the reservoir, creating expansion pressure for fracturing. The phase transition also enables automatic flow-back and eliminates residual liquid in the formation, solving water consumption and pollution problems.
2Stability of the object's composition
If polymer reinforcers are used in conventional fracturing fluids, then the fluid can maintain stability, but the polymer is easily adsorbed on porous medium surface reducing pore and throat volume
Solution Approach 1:
The patent extracts and removes polymer reinforcers from the fracturing fluid system entirely. Instead of using water-based fluids with polymer additives, the invention employs a pure CO2-based system with foam stabilizers that do not contain polymer materials. This extraction eliminates polymer adsorption on porous medium surfaces and preserves the original pore and throat volume of the shale reservoir.
Solution Approach 2:
The patent introduces foam stabilizers (surfactants) as intermediary substances to maintain fluid stability without using polymers. The foam stabilizers create stable foam structures through surface activity at gas-liquid interfaces, providing the necessary viscosity and stability for fracturing operations without the harmful adsorption effects of polymer reinforcers.
3Ease of operation
If water-based fracturing fluid is used, then the fracturing process can proceed, but clay swelling occurs damaging water-sensitive reservoirs
Solution Approach 1:
The patent changes the chemical composition parameter from water-based to CO2-based system. By replacing water with CO2 as the fracturing fluid medium, the chemical environment that causes clay swelling is eliminated. CO2 does not induce clay hydration and swelling reactions, thereby protecting water-sensitive reservoirs while maintaining ease of fracturing operations through CO2's favorable flow and pressure characteristics.
Solution Approach 2:
The patent creates an inert CO2 environment for the fracturing process. CO2 acts as an inert gas that does not chemically react with or hydrate clay minerals in the shale formation. This inert atmosphere prevents clay swelling and protects the integrity of water-sensitive reservoirs during fracturing operations, while still enabling effective fracture creation and proppant placement.
4Productivity
If conventional fracturing fluid is used, then the fracturing stimulation can be performed, but flow-back rate is low and waiting time for gas production is long
Solution Approach 1:
The patent utilizes CO2 phase transition from liquid to gas as the driving mechanism for rapid flow-back. After injection, CO2 expands and transitions to gas phase, creating pressure differential that automatically drives the fluid back through the wellbore. This phase transition mechanism enables high flow-back rates and eliminates the need for long waiting periods, significantly improving gas production efficiency and reducing time loss.
Solution Approach 2:
The patent ensures continuous useful action through the CO2 system. The CO2 foam maintains stability during injection, then continuously expands and flows back without interruption. The phase change process occurs continuously, maintaining pressure and flow throughout the operation. This continuity eliminates downtime and waiting periods, maximizing productivity and minimizing time loss for gas production.
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 foam fracturing fluid achieves high stability and low water consumption, reducing damage to shale gas reservoirs, facilitating rapid gas production, and enabling efficient fracturing in water-deficient areas with reduced environmental impact and improved viscosity-temperature stability compared to traditional fluids.
Implementation Method 1
dissolving a mixture of gas-soluble foaming agents in liquid CO2
Implementation Method 2
a water-soluble surfactant
Implementation Method 3
hydrophobic silica nanoparticles
Implementation Method 4
saturated vapor of the liquid CO2
Data Source
AI summary
The disclosure discloses a foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO2 for shale gas development, and a preparation method thereof. The foam fracturing fluid is prepared from a liquid CO2 phase, a gas phase and a nano-enhancer; the liquid CO2 phase is formed by dissolving a mixture of gas-soluble foaming agents in liquid CO2; the gas phase is a gas mixture of phlogisticated air and saturated vapor of the liquid CO2; the nano-enhancer is an aqueous solution of a mixture of hydrophobic silica nanoparticles, a cosolvent and a water-soluble surfactant. In the fracturing fluid prepared by the present disclosure, the phlogisticated air was encapsulated by the liquid CO2 to form an interface layer, the liquid CO2 was further encapsulated by the nano-enhancer to form the other interface layer, which enhanced the structural stability of the fracturing fluid while achieving high viscosity and thermal stability.