Abstract: A method of increasing the permeability of a subsurface formation by the utilization of a Bingham plastic fracture fluid. The Bingham plastic fracture fluid is pumped into a preformed fracture or a fracture formed with the Bingham plastic fluid and hydraulic pressure is imparted to the formation which is greater than that which was required to initially fracture the formation (i.e., the formation is overpressurized) by either (1) relieving the pumping pressure on the Bingham plastic fluid in the fracture and allowing the fracture to heal and thereafter reapplying the pumping pressure on the Bingham plastic fluid in an increased amount, e.g., an amount sufficient to move the Bingham plastic fluid in the fracture; or (2) continuing pumping of the Bingham plastic fluid into the fracture such that the friction drop caused by the continued pumping results in such increase in pressure.