Multi-Layer Coated Proppant for High-Pressure Fracturing
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Solution Overview
Problem
Conventional proppants break under downhole stress and temperatures, leading to the generation of proppant fines that can restrict flow conductivity in subsurface formations during hydraulic fracturing, and existing coatings are not strong enough to withstand pressures greater than 8000 psi.
Innovation Solution
A coated proppant comprising a proppant particle with an intermediate cross-linked terpolymer layer and an outer resin layer, where the terpolymer layer is formed from a combination of monomers such as styrene and methyl methacrylate, and the outer resin layer includes cured epoxy resin and graphene, enhancing the proppant's mechanical strength and resistance to crushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional uncoated proppants are used, then they are simple and inexpensive, but they break under downhole stress and generate fines that restrict flow conductivity
Solution Approach 1:
The patent applies composite materials by creating a multi-layer coating structure consisting of an intermediate cross-linked terpolymer layer and an outer resin layer on the proppant particle. This composite structure combines different materials with complementary properties: the cross-linked terpolymer provides mechanical strength and adhesion, while the outer resin layer provides environmental resistance. The composite nature of this multi-layer coating resolves the contradiction by achieving superior proppant strength (27) through material composition rather than simple single-layer coatings, while the systematic approach to coating application keeps the complexity (36) manageable.
Solution Approach 2:
The patent applies segmentation by dividing the coating into distinct functional layers: an intermediate cross-linked terpolymer layer and an outer resin layer. Each layer serves specific functions - the intermediate layer provides adhesion and mechanical strength, while the outer layer provides resistance to downhole conditions. This segmented approach resolves the contradiction by achieving reliable proppant performance through specialized layers rather than requiring a single complex coating, thereby improving strength (27) while managing overall complexity (36).
2Strength
If conventional proppant coating techniques are used at temperatures greater than 250° C., then coating adhesion is improved, but the coating cannot withstand pressures greater than 8000 psi
Solution Approach 1:
The patent applies parameter changes by utilizing cross-linked terpolymers that can be cured at lower temperatures while achieving coatings that withstand pressures greater than 8000 psi. The cross-linking chemistry and polymer composition are specifically selected to provide high-strength coatings without requiring conventional high-temperature curing processes. This resolves the contradiction by changing the material parameters (polymer selection, cross-linking density) to achieve high coating strength (14) at reduced temperatures (17).
Solution Approach 2:
The patent applies composite materials by combining the intermediate cross-linked terpolymer layer with an outer resin layer, where each material is selected for specific properties. The cross-linked terpolymer provides a strong, adherent base layer that can be cured at lower temperatures, while the outer resin layer provides additional strength and environmental resistance. This composite approach resolves the contradiction by achieving high coating strength (14) through material composition rather than relying solely on high curing temperatures (17).
3Strength
If coated proppants with intermediate polymer layer and outer resin layer are used, then crush resistance is improved, but they cannot withstand pressures greater than 8000 psi
Solution Approach 1:
The patent applies parameter changes by selecting specific polymer compositions and cross-linking densities that enable the coating to withstand pressures greater than 12000 psi. The cross-linked terpolymer structure, with its specific monomer ratios and cross-linking agents, provides enhanced mechanical properties including higher modulus and strength. This resolves the contradiction by changing material parameters to achieve superior crush resistance (14) capable of withstanding extreme downhole pressures (11).
Solution Approach 2:
The patent applies segmentation by creating a multi-layer coating structure where each layer is optimized for specific functions. The intermediate cross-linked terpolymer layer provides a strong, rigid base that resists crushing, while the outer resin layer provides additional protection and environmental resistance. This segmented structure resolves the contradiction by achieving high crush resistance (14) through specialized layers rather than requiring a single thick coating, enabling the proppant to withstand pressures greater than 8000 psi (11).
4Strength
If proppant surface area is increased through coating, then crush stress distribution is improved, but fine production increases under high load
Solution Approach 1:
The patent applies composite materials by using a cross-linked terpolymer intermediate layer that provides excellent adhesion to the proppant surface, preventing fine generation. The cross-linked network structure creates a strong bond that distributes crush stress effectively across the proppant surface while maintaining structural integrity. This resolves the contradiction by achieving superior stress distribution (14) through the composite cross-linked structure that prevents fine production (31) even under high load conditions.
Solution Approach 2:
The patent applies parameter changes by optimizing the cross-linking density and polymer composition to achieve a coating that is both adherent and mechanically strong. The specific cross-linking agent selection and monomer ratios create a coating with optimal mechanical properties that distributes stress uniformly while resisting fragmentation. This resolves the contradiction by changing material parameters to achieve effective stress distribution (14) without generating fines (31) under high load.
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 coated proppant exhibits reduced fine production at higher loads, improved hardness, elastic modulus, and thermal stability, allowing it to maintain fracture conductivity and withstand pressures up to 12000 psi with fine production between 2.0% to 10.0%, and 10000 psi with fine production between 0.5% to 5.0%, thereby enhancing oil and gas production.
Implementation Method 1
an intermediate cross-linked terpolymer layer encapsulating the proppant particle
Implementation Method 2
an outer resin layer encapsulating the intermediate cross-linked terpolymer layer
Data Source
AI summary
A coated proppant having a proppant particle, an intermediate cross-linked terpolymer layer encapsulating the proppant particle, and an outer resin layer encapsulating the intermediate cross-linked terpolymer layer. The proppant particle is selected from sand, ceramic, glass, and combinations thereof. The intermediate cross-linked terpolymer layer includes styrene, methyl methacrylate, and divinyl benzene. The outer resin layer includes a cured epoxy resin formed from an epoxy resin and a curing agent.