Carbon Dioxide Fracturing Fluid for Shale Stimulation
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Solution Overview
Problem
Conventional hydraulic fracturing methods are costly and can damage low-permeability hydrocarbon-bearing shale formations, particularly in tight gas shale formations like the Barnett Shale, and water-based fracturing is impractical due to high residual water and limited water supply issues, with existing methods failing to effectively stimulate methane production.
Innovation Solution
A carbon dioxide treatment fluid with a viscosity of less than 10 mPa-s at a shear rate of 100 s−1, comprising at least 90% to 100% carbon dioxide, is introduced into the formation at pressures above the fracture pressure to effectively fracture and stimulate hydrocarbon-bearing shale formations, potentially including surfactants and proppants, and may be used in conjunction with an aqueous fluid for enhanced fracture creation and methane displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional viscosified fracturing fluids are used, then fracture creation and proppant transport are facilitated, but formation damage occurs and cleanup costs increase
Solution Approach 1:
The patent changes the fundamental parameter of the fracturing fluid from water-based to carbon dioxide-based, which fundamentally alters the interaction with the formation. CO2 fracturing fluids do not cause the formation damage associated with water-based fluids while maintaining effective fracture creation capability, thus resolving the contradiction between ease of manufacture and harmful effects on the formation.
Solution Approach 2:
The patent employs a disposable, environmentally benign CO2 fracturing fluid that can be introduced into the formation and then naturally decomposes or is flushed out without leaving harmful residues. This eliminates the need for extensive cleanup operations and avoids long-term formation damage, addressing both the effectiveness and harm reduction aspects of the contradiction.
2Ease of manufacture
If water-based fracturing fluids are used, then fracture creation is effective, but residual water remains in the formation reducing permeability
Solution Approach 1:
The patent changes the fluid composition parameter from water-based to carbon dioxide-based, which fundamentally alters the residual fluid problem. CO2 does not remain trapped in the formation in the same way water does, thereby preserving formation permeability while maintaining effective fracture creation, thus resolving the contradiction between fracture effectiveness and permeability retention.
3Ease of manufacture
If viscosified fracturing fluids are used, then proppant transport is facilitated, but cleanup operations are required and costs increase
Solution Approach 1:
The patent uses a disposable CO2-based fracturing fluid that naturally decomposes or is easily flushed from the formation without requiring complex cleanup operations. This eliminates the substantial loss of substance and associated costs related to fluid recovery and disposal that are typical with conventional water-based viscosified fluids, while still enabling effective proppant transport during the fracturing operation.
4Ease of manufacture
If conventional fracturing fluids are used in tight gas shale formations, then fracture creation is achieved, but methane production stimulation is insufficient
Solution Approach 1:
The patent changes the fracturing fluid from conventional water-based to carbon dioxide-based, which fundamentally improves methane production stimulation in tight gas shale formations. CO2 not only creates effective fractures but also displaces adsorbed methane and enhances gas production, thus resolving the contradiction between fracture creation capability and methane production stimulation.
Solution Approach 2:
The patent converts the natural affinity of CO2 for adsorbed gases into a beneficial effect. By using CO2 as the fracturing fluid, the system simultaneously achieves fracture creation and methane displacement, turning what would normally be a separate operation into a unified process that enhances both fracture effectiveness and gas production stimulation.
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 carbon dioxide treatment fluid effectively fractures and stimulates methane production by displacing adsorbed methane, reducing formation damage, and can be used in water-scarce areas, providing longer-term gas production enhancement and minimizing residual fluid in the formation.
Implementation Method 1
displacing adsorbed methane
Implementation Method 2
displacing adsorbed methane
Implementation Method 3
introduced into the formation at a pressure above the fracture pressure of the formation
Implementation Method 4
minimizing residual fluid in the formation
Data Source
AI summary
A method of treating a shale-containing subterranean formation penetrated by a wellbore is accomplished by forming a carbon dioxide treatment fluid having a viscosity of less than about 10 mPa-s at a shear rate of about 100 s−1. The carbon dioxide treatment fluid is introduced into the formation through the wellbore at a pressure above the fracture pressure of the formation. In certain embodiments, the treatment fluid may be comprised of from about 90% to 100% by weight carbon dioxide and may contain a proppant. A method of treating hydrocarbon-bearing, shale-containing subterranean formation penetrated by a wellbore may also be carried out by forming a carbon dioxide treatment fluid and introducing the carbon dioxide treatment fluid into the formation through the wellbore at a pressure above the fracture pressure of the formation. The formation being treated may have a permeability of less than 1 mD.