Proppant conductivity in fractures at closure is crucial to ultimate hydrocarbon recovery from reservoirs. The proppant distribution inside the fracture determines the conductivity. This paper presents the application of solids-free channel fracturing treatment in microfractures. Microproppant (MP) agglomeration forms mini-pillars that support the microfractures to help prevent their complete closure and to provide conductive flow paths. Mathematical modeling of the conductivity that results from the microproppant pillars is presented and compared with the experimental data for validation using split cores of an Eagle Ford shale outcrop sample. Proppant embedment caused by the fracture deformation is estimated using the numerical model.

This paper presents a new three-dimensional (3-D) mathematical model that couples the solids and produced-fluids fracture-flow fluid mechanics with the deformable proppant pillars. MP aggregates/pillars are modeled as deformable cylindrical agglomerates, and the particles are modeled as deformable aggregates that deform under the closure stress. The fluid flows inside the fracture when there is a pressure differential. The propped microfractures are modeled as deformable solids that interact with the fluid flow. The fracture deforms as a result of closure and fluid stress. The model captures the fracture and pillar deformations using moving-mesh capability.

Simulations of closure stress with multiple pressure differentials for flow through the solids-free channels were performed to compare the conductivity obtained from the experiments using the split Eagle Ford shale core. MP aggregates, with less supporting surface area, must support higher closure stress compared to the conventional packed-proppant fracture, which has higher stiffness and lower embedment. Core samples treated with MP droplets were tested to obtain the experimental conductivity data. The results showed that the MP aggregates provided better conductivity than the partial monolayer of MP particulates were uniformily distributed and the number of droplets was properly limited. This was validated both qualitatively and quantitatively during the experiments. An uncertainty analysis using the simulation model revealed that the MP aggregate height significantly influenced conductivity and, therefore, should be optimized to enhance production.

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