A method is given for inducing heterogeneous proppant placement in a hydraulic fracture in a subterranean formation by causing proppant aggregation through a gel phase transition or chemical transformation in the proppant carrier fluid. Proppant aggregation may be induced by causing or allowing syneresis of the polymer gel that viscosifies the fluid; formation of a polyelectrolyte complex from cationic and anionic polymers included in or created in, the fluid; and by increasing the temperature of the fluid above the critical solution temperature of a polymer in the fluid. The proppant carrier fluid may be formulated such that these transformations occur naturally during or after proppant injection, and the transformations may be chemically triggered or delayed.
