Can Hydraulic Fractures in Granitic Rock Remain Permeable Without Proppants?

Abstract

An alternative design in multi-stage hydraulic fracturing for EGS is to create closely-spaced fractures that undergo shear deformation due to their mutual stress shadow. It is shown that by sequentially placing a number of hydraulic fractures close to one another, the induced shear leads to self-propping. The primary motivation for this approach is to avoid proppant use, which is a challenge under high temperature conditions. A few field and laboratory cases are presented to illustrate that fractures in hard granite rocks remain permeable even when they experience high stress conditions. The data shows that if shear deformation can be induced on neighboring hydraulic fractures, it can promote self-propping, lowering the near wellbore pressure drop and providing a permeable pathway between the injection and production wells. This would avoid the challenges associated with proppant availability and potential complications related to proppant transport into the surface facilities.