Gravity Hydraulic Fracturing: A Method to Create Self-driven Fractures

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Salimzadeh, Saeed ORCID ID icon; Zimmerman, Robert; Khalili, Nasser


Journal Article

Geophysical Research Letters



In this study, we investigate the possibility of using a high-density (heavy) fluid to induce downward fracture growth in a hydraulic fracturing process. We propose a mathematical model to calculate the minimum amount of a dense fluid required to trigger downward fracture propagation under gravity forces, and we verify the calculated minimum volume of the dense fluid by means of numerical simulations. Simulation results show that when the injected fluid exceeds the minimum amount, a steady downward growth of the hydraulic fracture is obtained. The fracture propagation consists of two distinct responses: the classical hydraulic fracturing process during injection, followed by post-injection gravity-driven fracture propagation. The first response can occur under either toughness-dominated, viscosity-dominated, or an intermediate hydraulic fracturing regime, depending on fluid rheology, rock properties, and injection scenario. The second response occurs mainly under the toughness-dominated regime, meaning the fracture propagates when the fracture toughness has been reached at the fracture tip. In the latter case, the speed of the downward fracture growth depends on the viscosity, and weight of the injected dense fluid. A dimensionless time is defined to capture different parameters affecting the gravity-driven fracture propagation, and to make the comparison between different cases possible.

American Geophysical Union

Gravity fracturing; dense fluid; hydraulic fracturing; heavy metals

Geomechanics and Resources Geotechnical Engineering


Journal article - Refereed


Salimzadeh, Saeed; Zimmerman, Robert; Khalili, Nasser. Gravity Hydraulic Fracturing: A Method to Create Self-driven Fractures. Geophysical Research Letters. 2020; 47:e2020GL087563.

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