EAGER: Pickering Emulsions for Hydraulic Fracturing Applications

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

In hydraulic fracturing high pressures are applied to induce fractures within shale formations. Sand and other solid particles (known as proppants) are then injected to prevent the collapse of the fractures once the pressure is released.These propped fractures ease the extraction of natural gas/oil. Sand has the disadvantages of not distributing evenly within the fractures, and of not reaching fractures far from the wellbore. This limits the amount of natural gas/oil that can be extracted from a given shale formation. Research is being conducted in materials sciences to produce proppantsthat are uniform in size (so that they will not clog the fractures), small (so that they canpenetrate narrow fractures), mechanically strong (to maintain the fractures open even when exposed to high subsurface pressures), and light (to diffuse farther from the wellbore, allowing the extraction of larger amounts of natural gas/oil from one fracture). This proposal intends to explore whether Pickering emulsions could be used to prevent the collapse of the hydraulic fractures once the pressure is released. Pickering emulsions e.g., water in oil) are stabilized by solid particles. They find numerous applications in areas as diverse as food preparation, cosmetics,drug delivery, and catalytic processes. The results obtained so far in the PIs laboratory,summarized in the narrative, have been obtained for bulk Pickering emulsions.Such studies have quantified the effect of solid particles on the water-decane interfacial tension, and the mechanism of dropletcoalescence. Current research is being conducted to clarify the interfacial structure anddynamical properties for systems composed by mixtures of different solid particles.This proposal stems from the hypothesis that emulsions might allow for a bettercontrolled distribution of the proppants within a fracture, possibly far from the wellbore. In the systems of interest the proppants will have the dual role of fracture stabilizers and emulsion formers.It is anticipated that once the emulsions are destabilized because of particle-rock interactions,the proppants will adsorb onto the rock surface.By controlling the emulsion stability within different sub-surface formations it will be possible to design shale-specific proppants. The intellectual merit of the proposed research consists in the evaluation of a new method to inject proppants within hydraulic fractures (Pickering emulsions instead of aqueous dispersions). If successful, this exploratory research could lead to the exploitation of larger amounts of the natural gas/oil stored in shale formations. Broader impacts. One post-doctoral researcher will conduct this exploratory research over a period of one year. The results obtained will be used to test our hypothesis. If successful, the proposed research could bring enormous economical advantages to the nation because the hydraulic fracturing stage constitutes one of the most expensive stages in the well drilling, and because more natural gas will be produced from a single well. Potential impacts are also expected on other technologies (e.g., cosmetics and drugdelivery), as our research will lead to better fundamental understanding of Pickeringemulsions. The research results will be integrated in teaching and outreach activities, following our track record.