Orbital Atk, Inc.

Alliant Techsystems Inc.

Thiokol Corporation

Northrop Grumman Systems Corporation

John A Arrell, Jr

Steven E Moore

Francois X Prinz

Peter L Atkeson

John W Cooper

Ronald S Borja

William J Slade

Paul P Hebert

A downhole sealing apparatus comprises a propellant section and a sealing element section adjacent the propellant section. The propellant section comprises an outer housing, at least one propellant structure within the outer housing, and at least one initiator device adjacent the at least one propellant structure. The sealing element section is configured to isolate a region of a borehole in a subterranean formation responsive to pressure of gases produced through combustion of at least one propellant of the at least one propellant structure of the propellant section. A downhole assembly and a method of isolating portions of a borehole in a subterranean formation are also disclosed.

Downhole sealing apparatuses and related downhole assemblies and methods

Downhole stimulation tools include a housing and at least one propellant structure within the housing comprising at least one propellant grain of a formulation, at least another propellant grain of a formulation different from the formulation of the at least one propellant grain longitudinally adjacent the at least one propellant grain, and at least one initiation element proximate at least one of the propellant grains. At least one pressure containment structure is secured to the housing and comprises a seal element expandable in response to gas pressure generated by combustion of a propellant grain of the at least one propellant structure. Related methods are also disclosed.

Methods and apparatus for downhole propellant-based stimulation with wellbore pressure containment

A downhole stimulation tool comprising an outer housing exhibiting apertures extending therethrough, opposing propellant structures within the outer housing, and at least one initiator adjacent each of the opposing propellant structures. Each of the opposing propellant structures comprise at least one higher combustion rate propellant region, and at least one lower combustion rate propellant region longitudinally adjacent the at least one higher combustion rate propellant region. Additional downhole stimulation tools and methods of stimulating a producing formation are also disclosed.

Downhole stimulation tools and related methods of stimulating a producing formation

Propellant structures and stimulation tools incorporating propellant structures may comprise composite propellant structures including two or more regions of propellant having different compositions, different grain structures, or both. An axially extending initiation bore containing an initiation element may extend through a center of the propellant structure, or may be laterally offset from the center. An offset initiation bore may be employed with a composite grain structure. Methods of tailoring ballistic characteristics of propellant burn to result in desired operational pressure pulse characteristics are also disclosed.

Method and apparatus for ballistic tailoring of propellant structures and operation thereof for downhole stimulation

Electronic time delay apparatuses and methods of use are disclosed. An explosive or propellant system, which may be configured as a well perforating system includes an electronic time delay assembly comprising an input subassembly, an electronic time delay circuit, and an output subassembly. The input subassembly is activated by an external stimulus, wherein an element is displaced to activate an electronic time delay circuit. The electronic time delay circuit comprises a time delay device coupled with a voltage firing circuit. The electronic time delay circuit counts a time delay, and, upon completion, raises a voltage until a threshold firing voltage is exceeded. Upon exceeding the threshold firing voltage, a voltage trigger switch will break down to transfer energy to an electric initiator to initiate an explosive booster within the output subassembly. The explosive booster provides a detonation output to initiate the next element explosive or propellant element, such as an array of shaped charges in the well perforating system.

Methods and apparatuses for electronic time delay and systems including same

Electronic time delay apparatuses and methods of use are disclosed. An explosive or propellant system, which may be configured as a well perforating system includes an electronic time delay assembly comprising an input subassembly, an electronic time delay circuit, and an output subassembly. The input subassembly is activated by an external stimulus, wherein an element is displaced to activate an electronic time delay circuit. The electronic time delay circuit comprises a time delay device coupled with a voltage firing circuit. The electronic time delay circuit counts a time delay, and, upon completion, raises a voltage until a threshold firing voltage is exceeded. Upon exceeding the threshold firing voltage, a voltage trigger switch will break down to transfer energy to an electric initiator to initiate an explosive booster within the output subassembly. The explosive booster provides the detonation output to initiate the next element explosive or propellant element, such as an array of shaped charges in the well perforating system.

An electrically actuated igniter squib is formed by welding a cup containing a pyrotechnic material to a header inserted in the cup, thus forming a hermetic seal. The diameter of the header exceeds the diameter of the cup and the two are joined by forcing, under pressure, the header into the cup to achieve a tight readily welded joint.

Growing community of inventors

Lincoln University, PA, United States of America

John A Arrell, Jr