Smart expandable proppants to achieve sustainable hydraulic fracturing treatments

Hydraulic fracturing is recognized as the primary technique to achieve economic oil and gas production from low permeability reservoirs like shale and tight-sand formations. One of the main challenges facing the oil and gas industry is maintaining the proppant functionality in the subsurface where replacement of proppant is only possible by expensive refracturing operations. Proppant crushing and proppant embedment have posed challenges for sustainable production from stimulated wells especially in soft and deep formations like Haynesville Shales. Experimental measurements show the strong impact of proppant stress and proppant embedment on reducing fracture conductivity. In this work, we intoduce a new class of smart "Expandable Proppants" (EP) to remotely control the expanding force and maintain the functionality of injected placed proppants. Our smart proppants are made out of thermoset shape memory polymers which are activated by formation's in situ temperature to effectively maintain or even increase fracture's width. A fully coupled CFD-DEM model is developed to study the effectiveness of expandable proppants and evaluate fracture conductivity enhancement via different combination and distribution of EP. In addition, a series of experiments were conducted in a modified API conductivity cell to measure the increase in fracture conductivity. Different conditions of temperature, confining stress, proppant size and concentrations are carried out to verify the optimum conditions.