Abstract: A fracturing system for wells has a propellant charge having a known surface area for combustion, and a combustion rate as a function of pressure with lower combustion rates at lower pressures and rapidly increasing combustion rates at higher pressures separated by a knee in the combustion rate function. The propellant charge is initially sealed within a vessel as it is inserted into a well. The system also includes means for creating openings in the vessel on ignition of the propellant charge in the well, such that the openings have a known combined flow area selected to create a condition of choked flow of combustion gases from within the vessel and maintain pressures within the vessel below the knee in the combustion rate function.

Abstract: An apparatus for fracturing a well has a propellant charge held by a carrier, and upper and lower restrictor plugs secured to the carrier above and below the propellant charge, respectively. The restrictor plugs allow a restricted flow of combustion gases generated by the propellant charge to pass the restrictor plugs, but maintain sufficient pressure in the well between the restrictor plugs to fracture the formation surrounding the well.

Abstract: An apparatus for fracturing wells employs a propellant charge and an ignition cord wrapped around the outer surface of the propellant charge to rapidly ignite the outer surface of the propellant charge.

Abstract: An apparatus for fracturing wells employs a propellant charge and an ignition cord wrapped around the outer surface of the propellant charge to rapidly ignite the outer surface of the propellant charge.

Abstract: A system for fracturing wells uses a primary propellant charge to initially produce pressures within the well in excess of the maximum fracture extension pressure of the surrounding formation, but below that which would cause damage to the well. A supplemental propellant charge burns for a substantially longer period of time than the primary propellant charge, and thereby maintains pressures within the well in excess of the maximum fracture extension pressure for a significant period of time following completion of the primary propellant burn.