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The United States of America As Represented by the United States

Halliburton Company

James O Johnson

James Marshall Barker

Starlin M Reid

Robert H Dinegar

An improved method of fracturing a geological formation surrounding a well bore is disclosed. A relatively small explosive charge is emplaced in a well bore and the bore is subsequently hydraulically pressurized to a pressure less than the formation breakdown pressure and preferably greater than the fracture propagation pressure of the formation. The charge is denoted while the bore is so pressurized, resulting in the formation of multiple fractures in the surrounding formation with little or no accompanying formation damage. Subsequent hydraulic pressurization can be used to propagate and extend the fractures in a conventional manner. The method is useful for stimulating production of oil, gas and possibly water from suitable geologic formations.

Method of fracturing a geological formation

An exploding bridge wire detonator for use in high temperature downhole oil well tools is set forth. It is made of a high temperature stable secondary explosive which will be exposed to extremely high ambient temperatures such as 500.degree. F. This apparatus includes a housing supporting a pair of conductor wires which connect with a sacrificial exploding bridge foil or wire connected across the conductor wires. The sacrificial bridge is immediately adjacent to the explosive material in cylindrical form, and a reflector is included therein. The reflector preferably has high shock impedance to reflect shock waves traveling through the explosive from the exploding bridge. The reflector is transverse to the explosive mass but does not fully block off explosive shock wave propagation through the explosive material.

Exploding bridge wire detonator with shock reflector for oil well usage

A detonator assembly is provided which is usable at high temperatures about 300.degree. C. A detonator body is provided with an internal volume defining an anvil surface. A first acceptor explosive is disposed on the anvil surface. A donor assembly having an ignition element, an explosive material, and a flying plate, are placed in the body effective to accelerate the flying plate to impact the first acceptor explosive on the anvil for detonating the first acceptor explosive. A second acceptor explosive is eccentrically located in detonation relationship with the first acceptor explosive to thereafter effect detonation of a main charge.

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Los Alamos, NM, United States of America

James O Johnson