Self-Suspending Proppant Coating for CO2 Fracturing
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Solution Overview
Problem
Conventional CO2-based hydraulic fracturing fluids lack sufficient viscosity to suspend proppant particles, limiting their use in fracturing operations due to the lack of CO2-soluble thickening agents.
Innovation Solution
Development of self-suspending proppants coated with a lightly crosslinked CO2-philic coating that constrains CO2 molecules, allowing them to remain suspended in CO2-based fluids and effectively prop open subterranean fractures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CO2-based fluids are used for hydraulic fracturing, then environmental soundness and non-aqueous alternative are improved, but viscosity and proppant suspension capability deteriorate
Solution Approach 1:
A CO2-philic polymer coating is applied as an intermediary layer between the proppant particles and the CO2-based fluid. This coating acts as a mediator that interacts with both the proppant surface and the CO2 molecules, enabling the proppant to suspend in the CO2 fluid without requiring the fluid itself to have high viscosity. The polymer coating specifically interacts with CO2 molecules through its CO2-philic properties, creating a suspension mechanism that resolves the contradiction between using CO2-based fluid and maintaining proppant suspension capability.
Solution Approach 2:
The invention changes the surface properties of the proppant particles by coating them with a CO2-philic polymer, thereby altering the interaction parameters between the proppant and the CO2-based fluid. This parameter change enables the proppant to interact favorably with the CO2 molecules, allowing suspension without requiring the bulk fluid to have enhanced viscosity. The coating modifies the interfacial properties and interaction forces, resolving the contradiction between CO2-based fluid usage and proppant suspension capability.
2Loss of substance
If CO2-based fluids are used for hydraulic fracturing, then water depletion is reduced, but thickening agent availability deteriorates
Solution Approach 1:
The CO2-philic polymer coating serves as an intermediary that enables proppant suspension in CO2-based fluids without requiring traditional water-soluble thickening agents. Since the coating specifically interacts with CO2 molecules, it provides the necessary suspension mechanism for CO2-based fluids, eliminating the need for water-soluble thickening agents and resolving the contradiction between water depletion reduction and thickening agent availability.
Solution Approach 2:
The invention extracts the thickening function from the bulk fluid formulation and transfers it to the proppant particle surface coating. By applying the CO2-philic polymer coating directly to the proppant, the suspension capability is extracted from the fluid system and embedded in the proppant itself, eliminating the need for separate thickening agents in the CO2-based fluid formulation.
3Stability of the object's composition
If proppant particles are coated with CO2-philic coating, then self-suspension in CO2-based fluid is achieved, but coating material selection becomes more restricted
Solution Approach 1:
The invention identifies and utilizes specific parameter changes in the coating material - namely, CO2-philicity and appropriate crosslinking density. By focusing on these critical parameters, the selection criteria for coating materials are refined: the material must have high CO2 affinity and appropriate crosslinking to enable self-suspension while maintaining proppant integrity. This parameter-based approach, while narrowing the material selection range, ensures optimal performance for CO2-based fluid applications.
Solution Approach 2:
The CO2-philic polymer coating provides local quality enhancement at the proppant surface, creating a specialized interface that interacts with CO2 molecules. This local modification of the proppant surface properties enables selective interaction with the CO2-based fluid, achieving self-suspension without requiring the entire proppant material or the bulk fluid to have specialized properties. The coating creates a localized functional layer that resolves the contradiction between self-suspension capability and coating material versatility.
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 CO2-philic coating's volumetric expansion increases the buoyancy of proppant particles, enabling them to self-suspend in CO2-based fluids without additional viscosifiers, thereby enhancing the effectiveness and efficiency of hydraulic fracturing treatments.
Implementation Method 1
The CO2-philic coating is lightly crosslinked and has a physical structure that constrains or is solvated by CO2 molecules
Implementation Method 2
The CO2-philic coating is lightly crosslinked and has a physical structure that constrains CO2 molecules
Data Source
AI summary
Self-suspending proppants including proppant particles coated with a CO2-philic coating are provided. The CO2-philic coating may be lightly crosslinked and may have a physical structure that constrains CO2 molecules. Methods of making self-suspending proppants may include coating a proppant particle with a polymerizable precursor material of a CO2-philic material and polymerizing the polymerizable precursor material to form a self-suspending proppant are also provided. Additionally, hydraulic fracturing fluids that may include a CO2-based fluid and the self-suspending proppants and methods of treating subterranean formations by contacting a subterranean formation with hydraulic fracturing fluid and propagating at least one subterranean fracture are provided.