Abstract: A method for increasing the productivity of wells completed in soft acid-soluble producing formations, comprising the steps of: producing in such formation a fracture containing a viscous fluid; injecting an acid solution wherein the viscosity of the contained fluid is preferably at least 50 times greater than the acid solution into the formation to create acid etched fingering channels; injecting into the formation a fluid with a propping agent the viscosity of which is at least equal to the acid solution until propping agent is deposited in the fracture at least in those areas where channels have been etched; and lowering the pressure within the fracture to allow it to move towards a closed position. By controlling the viscosity ratios of viscous fluid to acid solution and carrying fluid to acid solution long fingering acid etched channels are created and propped such that the channel walls of the soft formation are propped open when the fluid pressure in the fracture is reduced.

Abstract: A fracturing and acidization method for increasing the productivity of relatively hard acid-soluble formations about a perforated well, comprising the steps of producing a formation fracture containing a viscous fluid and propping agent; injecting an acid solution having a viscosity value fifty times less than the contained viscous fluid into the fluid filled fracture, thereby forming etched channels in the fracture walls and displacing the propping agent from such channels; and lowering the fluid pressure in the fracture to allow the walls thereof to become displaced towards a closing position until held open by the propping agent. Channels so formed have a greater width than can be formed by conventional techniques and consequently substantially increase the productivity of such formations.