Cement-Coated Proppant Particles for Fracture Conductivity
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Solution Overview
Problem
Current proppants used in hydrocarbon fracturing, such as sand and ceramics, face issues with embedment in the fracture face, leading to reduced fracture conductivity and increased costs due to resin coating requirements, and have limitations in stress resistance and fines generation, which affect hydrocarbon recovery.
Innovation Solution
Particles with a substrate coated in a layer of cement in a state of suspended hydration are introduced into the subterranean formation, allowing for improved bonding and reduced embedment, enhanced crush resistance, and lower costs through the use of a cement coating that hardens in situ, forming a stable aggregate matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sand is used as proppant, then cost is reduced, but stress resistance is poor resulting in fines generation and loss of fracture conductivity
Solution Approach 1:
The invention uses a composite structure consisting of a substrate particle (sand, ceramic, or other material) coated with a cement layer. This composite structure combines the cost advantage of sand substrates with the strength benefits of cement coating, achieving both economical and mechanically robust proppant performance.
Solution Approach 2:
The cement coating undergoes hydration parameter changes when exposed to formation water, transitioning from a suspended hydration state to secondary hydration. This parameter change enables the coating to develop binding properties in situ, enhancing particle strength and resistance to stress-induced fines generation.
2Strength
If ceramic proppant is used, then stress resistance is improved, but embedment in fracture face increases reducing fracture conductivity
Solution Approach 1:
The cement coating's hydration state changes in response to formation water, allowing the particle surface properties to adapt. This parameter change enables the coating to reduce embedment while maintaining stress resistance, as the hydrated cement layer provides a more compliant interface with the fracture face.
Solution Approach 2:
The cement coating provides localized modification of the particle surface properties. The coating thickness and hydration state can be controlled to create optimal local characteristics at the particle-fracture face interface, reducing embedment while preserving overall particle strength.
3Strength
If resin coating is applied to proppant, then bonding between particles is improved, but cost increases significantly
Solution Approach 1:
The invention replaces expensive resin coatings with a cement-based coating system that utilizes the abundant formation water for hydration. This substitution dramatically reduces material costs while achieving comparable or superior bonding performance through the cement hydration process.
Solution Approach 2:
The cement coating system is self-activating upon contact with formation water, eliminating the need for external bonding agents or additional chemicals. The hydration process automatically provides the bonding mechanism, reducing operational complexity and cost.
4Ease of operation
If carrier polymer is used with proppant, then proppant placement is improved, but fracture closure time increases and cleanup becomes challenging
Solution Approach 1:
The invention extracts the carrier polymer from the proppant system, using standalone cement-coated particles that do not require polymer carriers for placement. This elimination of the polymer component directly reduces fracture closure time and simplifies cleanup operations.
Solution Approach 2:
The cement coating acts as an intermediary that provides the necessary particle-to-particle bonding without requiring a carrier polymer. The hydrated cement layer facilitates particle aggregation and placement stability directly through its binding properties, eliminating the need for polymer mediators.
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 cement-coated particles improve fracture conductivity and reduce fines generation, maintaining integrity under high stress and reducing operating costs by preventing proppant flowback and embedment, while allowing for the use of lower-cost, non-proppant grade materials.
Implementation Method 1
The cement may be in a state of suspended hydration... introducing moisture to the subterranean formation via the well bore... allowing the particles and the moisture to contact one another... Contact between the particles and the moisture may cause the cement to move from a state of suspended hydration to a state of secondary hydration
Data Source
AI summary
A method of treating a subterranean formation via well bore may include introducing a plurality of particles into the subterranean formation via the well bore, each particle having a substrate and a layer of cement on the substrate. The cement may be in a state of suspended hydration and the method may include introducing moisture to the subterranean formation via the well bore. The method may also include allowing the particles and the moisture to contact one another. Contact between the particles and the moisture may cause the cement to move from a state of suspended hydration to a state of secondary hydration.