PhD- Fluid Dynamics of Hydraulic Fracturing

Hydraulic fracturing, or `fraccing’ as it is commonly called, is the process of drilling and then injecting fluid into the ground at high pressures in order to fracture shale rocks and, in doing so, release natural gas stored there. In the United States, over 10 billion cubic feet of natural gas are obtained each day by this process. The large-scale production of natural gas in this fashion has far reaching implications on the energy market, as it shifts from a primarily fossil fuel base to a greater inclusion of renewable sources. Natural gas plays an important role in this transition.

During the fracturing, millions of tons of water, mixed with sand and chemical additives, are needed at each well site during its exploitation. The added sand particles, referred to as `proppant`, are deposited by the flow of the injected liquid, serving as the support for the fractures, `propping’ them open and increasing the permeability of the rock. The success of the fracturing is therefore largely dependent upon the dynamics of the flow, the transport of these particles and their deposition along the fractures. These dynamics are complex and involve various forces acting on the particles as they are carried by the flow. These forces, in turn, may depend on the particle properties such as their shape, size and composition, as well as fracture properties such as orientation with respect to gravity, surface roughness and permeability.

 

Knowledge of the flow and deposition is important for the subsequent efficient extraction stage. However, environmental concerns related to possible gas leakage leading to atmospheric emission and contamination of drinking water, may also be addressed through a better understanding of the process. While fraccing has been around for decades, the technological breakthrough facilitating shale-gas extraction through fraccing commenced only recently, some fifteen years ago. Because of this short history, there are many scientific avenues to be investigated before the process canbe made as economically viable and environmentally safe as possible.

The proposed research is aimed at quantifying these physical processes at a fundamental level. The insight gained by such analysis is crucial in developing innovative engineering designs and providing linkages between the Foreseer tool and underpinning physical models that affect energy and water and land domains with an initial focus on unconventional gas extraction.