Physics Today, Backscatter, March 2018
James M. Campbell, Deren Ozturk, and Bjørnar Sandnes
Phys. Rev. Applied 8, 064029 – Published 29 December 2017
Gas-driven fracturing underlies both natural and industrial processes, such as volcanic degassing, methane venting, stimulated hydrocarbon extraction, and treatment of contaminated soil. The authors show how in such a complex system the capillary, frictional, and viscous interactions together produce a range of fracture patterns, with cracks separated by a characteristic length that varies based on the conditions. Discovering how material properties and injection rate affect these patterns helps to establish a physics framework for optimizing permeability and assessing risk in gas-driven fracturing of hydrocarbon reservoirs and remediation of polluted soil.
Time lapse movie of pattern formation in a drying particulate suspension. A mixture of silicon dioxide particles and water is spread out on a horizontal glass slide, and evaporation generates a flow from the center towards the edge of the droplet. Large particles become pinned to the substrate by the fluid meniscus, and act like obstacles to the flow. Gradually smaller particles become trapped by the meniscus, and deposits grow sideways into irregular stripes. Patterns like these can be seen on the sides of muddy cars on rainy days.