Particle agglomeration in sheared fluids

Orthokinetic agglomeration is a candidate mechanism for selectively increasing proppant size in large fractures during subsurface flow. The rate of agglomeration shows a maximum at shear rates of 275 s-1 suggesting that the ability to selectively grow particles depends on the hydrodynamics. Growth rates are shown to increase with increasing ion availability per unit surface area. The availability of solution ions and the average shear rates are the key parameters determining agglomeration. Precipitated species act as bridging "glue" between particles. Reduced growth rates are found for higher particle concentrations and also for larger particle size. This result has possible applications for shear-selective mechanical blocking which can be applied to solve the problem of high conductivity paths in fractured reservoirs for both traditional oil recovery as well as geothermal heat mining from fractured basement.