Abstract: A hydrocarbon producing well is treated by first igniting a gas generating charge in the well to clean out perforations communicating between the casing and the formation without creating high permeability channels adjacent the perforations or fracturing the formation in a macroscopic sense. Then, a treatment liquid is injected into the wells by a gas generating propellant charge placed in the production string and then ignited. The propellant charge is designed to produce a minimum horsepower sufficient to push the liquid more-or-less equally through all of the open perforations. The propellant charge is designed to produce a maximum horsepower which is less than what is necessary to fracture the formation. Basically, the combustion rate of the propellant charge is reduced by one of a multiplicity of techniques to produce a long, relatively slow combustion rate.

Abstract: An explosive or combustion actuated subsurface well tool includes a firing head for initiating operation of the tool in response to a projectile, such as a ball or go-devil, being pumped down a tubing string extending from the surface. The firing head includes a passage sized to closely receive the ball or go-devil, in either a sealed manner in which substantially no liquid leaks around the pumped projectile or in an unsealed manner in which a small amount of liquid leaks around the projectile. As the projectile moves into the passage, the pressure drop across the projectile becomes quite large creating a large force sufficient to shear a safety pin, drive home a firing pin or otherwise initiating operation of the subsurface well tool.

Abstract: A gas generating type tool includes a propellant charge having an axially extending passage receiving therein an ignition tube containing a quantity of easily ignited, fast burning powder. The propellant and ignition tube are separately handled and/or transported until ready to run into the well. The tube slides easily into the propellant passage. The propellant passage is at least about 12% larger in cross-section than the ignition tube and not more than about 55% larger in cross-section. In circular cross-sections, the propellant passage is at least about 6% greater in diameter and not more than about 25% greater in diameter.

Abstract: A gas generating type fracturing tool is designed to work on long productive intervals and includes a series of separate propellant charges, an igniter for initiating combustion of one of the charges and means for transferring combustion from one charge to the next. In one embodiment, combustion of the charges occurs one after another with little or no delay between successive charges. In other embodiments, a delay is incorporated in the combustion train between successive charges. Some embodiments are specifically designed to unplug uncemented slotted liners and have very small gas generation capability.

Abstract: A gas generating type fracturing tool includes a propellant charge and an ignitor for initiating combustion of the propellant. When combustion starts, a pressure buildup inside the tool manipulates a brake or drag acting against the inner casing wall to retard upward movement of the tool. A shear pin fails allowing a spring to move an element into frictional engagement with the casing string.

Abstract: A device for fracturing a subterranean formation includes a propellant charge which generates, during combustion, a large quantity of high pressure combustion products. A drogue is provided on the device to prevent or minimize rapid upward movement of the device during combustion. This obviates "bird nesting" of the wire line, wire line damage and the like.

Abstract: A subterranean formation is fractured by burning a quantity of fuel in an uncased bore hole to generate a large quantity of high pressure combustion products. These gases rapidly flow into the formation creating the fractures. The device is assembled in the well by placing a thermal ignitor in the well and delivering a quantity of fuel and oxidizer around the ignitor. The fuel and oxidizer comprise a flowable material and are either pumped or poured into the well.

Abstract: An oil or gas well is completed by cementing a casing string in a well having a special joint providing incipient perforations therein. The incipient perforations are closed during the cementing of the casing string in the well bore and are opened after the cement sets up. Preferably, the incipient perforations are opened concurrently with the fracturing of the cement sheath and the formation from which production is desired. The perforations of this invention are quite large and bear a ratio with the quantity of propellant in which there is at least 14 square inches of casing openings per cubic foot of propellant.

Abstract: An apparatus for stimulating a subterranean formation uses a gas generating propellant placed in the well adjacent the formation to be stimulated. The propellant is ignited to generate gas at sufficient pressure and in sufficient volume to fracture the formation to thereby improve its permeability or productivity. The device is designed to generate an initial pressure pulse of substantial amplitude to initiate fractures in the formation. Shortly, the pressure generated by the device falls off to a lower value and is sustained at that value for a relatively substantial length of time.

Abstract: A method of treating a hydrocarbon producing well involves injecting into the well a combustible mixture including a gaseous phase material. The combustible mixture is ignited to produce a quantity of hot combustion products which flow into a hydrocarbon bearing formation. Because of the relatively rapid travel of these combustion products, some fracturing of the formation occurs adjacent the well bore which increases permeability of the formation. When the formation contains low gravity, high viscosity oil, the hot combustion products also heat the oil thereby lowering its viscosity and also provides some gas which may become intermingled or dissolved in the oil to provide a drive mechanism for moving the oil into the well bore where it can be recovered by conventional pumping devices.

Abstract: A projectile having a length to diameter ratio greater than 6 to 1 is propelled from a launcher by a propellant charge toward a rock target at velocities of 500 ft./sec. and higher to more efficiently penetrate the rock for excavation purposes.

Abstract: A method of stimulation oil well production uses a gas generating chemical charge that is placed in the oil well bore at a depth of known oil productivity where it is ignited to generate a gas pressure-volume pulse of known pressure-time characteristics and time duration, the pressure time characteristics includes a pulsating pressure for greater penetration effect.

Abstract: Apparatus for stimulation of oil well production utilizes a gas generating chemical charge that is placed in the oil well bore at a depth of known oil productivity and ignited to produce a gas pressure-volume pulse of known pressure-time characteristics and time duration, including means for generating a pulsating gas pressure-volume pulse.