Coated Proppant Design for Settling Velocity Reduction
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Solution Overview
Problem
In slickwater fracturing, there is a challenge in balancing the properties of proppants and carrier fluids to maintain proppant suspension and mechanical strength, as strong proppants tend to settle prematurely in low viscosity fluids like slickwater, while lightweight proppants lack the necessary strength to resist fracture closure pressure.
Innovation Solution
Designing coated proppant particles with a selected coating material and thickness to reduce settling velocity, using equations to determine the optimal coating density and thickness based on the proppant material, fracturing fluid properties, and flow regimes, ensuring the proppant reaches the target destination without premature settling and maintains mechanical strength to resist closure pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strong proppants are used to resist fracture closure pressure, then mechanical strength is improved, but settling velocity increases causing premature settling in low viscosity carrier fluids
Solution Approach 1:
The patent applies composite materials by coating proppant particles with a material that has different density properties than the core proppant. This creates a composite structure where the inner proppant provides mechanical strength while the outer coating layer reduces the overall density, thereby reducing settling velocity in low viscosity carrier fluids without compromising the mechanical strength needed to resist fracture closure pressure.
2Speed
If lightweight proppants are used to reduce settling velocity, then suspension stability is improved, but mechanical strength decreases making them unable to resist fracture closure pressure
Solution Approach 1:
The composite structure allows the inner proppant core to provide mechanical strength while the outer coating provides density reduction. This resolves the contradiction by separating the functions of strength provision and weight reduction into different layers of the composite particle.
Solution Approach 2:
Different parts of the proppant particle have different properties: the inner core has high density and high strength, while the outer coating has low density. This local differentiation allows the particle to simultaneously achieve low settling velocity (due to reduced average density) and high mechanical strength (due to the strong core material).
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 proppants achieve reduced settling velocity during transport and increased mechanical strength to keep fractures open during production, enhancing hydrocarbon flow and fracture conductivity.
Implementation Method 1
determining a diameter of the coating material disposed on the proppant particle material based on the selected proppant particle material and the density of the coating material to achieve the target reduction in settling velocity
Data Source
AI summary
A process for designing a coated proppant particle for downhole transportation and placement. A carrier fluid may transport the coated proppant particle downhole. The process may include selecting a proppant particle material and a coating material. The process may also include selecting a target reduction in a settling velocity and determining a diameter of the coating material disposed on the proppant particle material based on the selected proppant particle material and the density of the coating material. The process for designing a coated proppant particle may include selecting a coating material thickness for coating on the proppant particle material and determining a coating material and design for coating on the proppant particle with the coating material thickness based on the selected proppant particle material and thickness of the coating material to achieve the target reduction in settling velocity.