Orbital Atk, Inc.

Steven E Moore

John A Arrell, Jr

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.

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Elkton, MD, United States of America

Steven E Moore