Multiphase fracturing of deformable media

点击翻译按钮获取中文摘要

Hydraulic fracturing, colloquially known as "fracking", has transformed the US energy sector in recent years, and the UK is now on the brink of a potential large scale development of a significant onshore shale gas resource. Fracking involves the injection of pressurized fracturing fluid that overcomes the confining pressure and tensile strength of the reservoir rock, breaking open fissures that act as conductive pathways in the otherwise impermeable shale. The water-based fracturing fluid is miscible with the host fluid, and must be injected at a faster rate than it dissipates within the shale play.The proposed project addresses an alternative fracturing mechanism: multiphase fracturing, where a gaseous phase penetrates a water saturated porous media. Unlike traditional fracking (a single phase process), the capillary forces acting at the gas/liquid/grain interface is expected to play a significant role in the fracture growth dynamics.This project will focus on developing a detailed understanding of the fundamental physical mechanisms that govern multiphase fracture growth. A custom made experimental flow rig will be used to study the fracture growth dynamics and the evolving fracture network pattern upon injection of a pressurized gas into a water-saturated, deformable porous media. Questions we seek to answer include: How does surface tension, wetting properties and grain size influence growth activity at the fracture tips? Can the evolving fracture pattern formation (and by extension the permeability of the fracture zone) be controlled using experimental parameters such as capillary forces, compressibility and injection rate?A second objective is to undertake a first fundamental study of CO2 fracturing, focusing on the complex interplay between the fracturing process, and the subsequent absorption and diffusive transport of CO2 within the pore space host fluid. Using CO2 as an unconventional fracturing fluid has potential for achieving high permeability fracture zones, increased methane recovery as CO2 binds preferentially to grain surfaces, and a combined process of shale gas recovery and large scale CO2 geo-sequestration.