Method and apparatus for ballistic tailoring of propellant structures and operation thereof for downhole stimulation
AssigneeOrbital ATK, Inc.
InventorsJohn A. Arrell, Jr., Steven E. Moore
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Abstract
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.
Claims23
A downhole stimulation tool, comprising:
- a housing;
- and
- a propellant structure within the housing and comprising:
- at least one propellant grain of a formulation;
- a single longitudinal bore extending through the at least one propellant grain;
- at least another propellant grain of a formulation different from the formulation of the at least one propellant grain adjacent the at least one propellant grain;
- and
- at least one initiation element for initiating the at least one propellant grain, the at least one initiation element disposed in the single longitudinal bore.
A downhole stimulation tool, comprising:
- a housing;
- and
- a propellant structure within the housing and comprising:
- at least one propellant grain of one of substantially cylindrical transverse cross-section and polygonal transverse cross-section having a single longitudinal bore extending therethrough laterally offset from a center of the at least one propellant grain;
- and
- one or more additional propellant grains, each additional propellant grain configured as a sleeve and surrounding another propellant grain, at least one of the additional propellant grains of a formulation different from a formulation of the at least one substantially cylindrical propellant grain;
- and
- at least one initiation element for initiating the at least one propellant grain within the longitudinal bore.
A method of operating a downhole stimulation tool, the method comprising:
- initiating a substantially cylindrical propellant grain of a formulation from a single longitudinally extending location within the propellant grain to burn the propellant grain in a radially extending direction;
- and
- initiating another propellant grain of a different formulation comprising a tubular, substantially cylindrical sleeve surrounding a substantially cylindrical exterior surface of the propellant grain along at least a portion of a boundary between the propellant grain and the another propellant grain.
A method of operating a downhole stimulation tool, the method comprising initiating a substantially cylindrical propellant structure from a single longitudinally extending location laterally offset from a center of the propellant structure within the propellant structure to burn the propellant structure in a laterally extending direction, the propellant structure comprising at least one propellant grain of a formulation and at least another propellant grain of a formulation different from the formulation of the at least one propellant grain adjacent the at least one propellant grain.
Dependencies are inferred from the claim text.