Proppants coated by piezoelectric or magnetostrictive materials, or by mixtures or combinations thereof, to enable their tracking in a downhole environment
First Claim
1. A method for tracking and monitoring proppants in a downhole environment, comprising the steps of:
- providing composite proppants, said composite proppants comprising a particulate substrate having an external surface, and from approximately 0.001% to approximately 75% by volume of a material having electromagnetic properties which change under a mechanical stress;
emplacing said proppants in a fracture in said downhole environment, whereupon they become subjected to the closure stress of said fracture, resulting in changes of electromagnetic properties of said composite proppants; and
measuring changes in said electromagnetic properties of the composite proppants to track and monitor the locations of said composite proppants.
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Accused Products
Abstract
A method for “tagging” proppants so that they can be tracked and monitored in a downhole environment, based on the use of composite proppant compositions comprising a particulate substrate coated by a material whose electromagnetic properties change at a detectable level under a mechanical stress such as the closure stress of a fracture. In another aspect, the invention relates to composite proppant compositions comprising coatings whose electromagnetic properties change under a mechanical stress such as the closure stress of a fracture. The substantially spherical composite proppants may comprise a thermoset nanocomposite particulate substrate where the matrix material comprises a terpolymer of styrene, ethylvinylbenzene and divinylbenzene, and carbon black particles possessing a length that is less than 0.5 microns in at least one principal axis direction incorporated as a nanofiller; upon which particulate substrate is placed a coating comprising a PZT alloy manifesting a strong piezoelectric effect or Terfenol-D manifesting giant magnetostrictive behavior to provide the ability to track in a downhole environment.
60 Citations
32 Claims
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1. A method for tracking and monitoring proppants in a downhole environment, comprising the steps of:
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providing composite proppants, said composite proppants comprising a particulate substrate having an external surface, and from approximately 0.001% to approximately 75% by volume of a material having electromagnetic properties which change under a mechanical stress; emplacing said proppants in a fracture in said downhole environment, whereupon they become subjected to the closure stress of said fracture, resulting in changes of electromagnetic properties of said composite proppants; and measuring changes in said electromagnetic properties of the composite proppants to track and monitor the locations of said composite proppants. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method for tracking and monitoring proppants in a downhole environment, comprising:
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providing a blend of proppants, comprising at least 1% by weight of composite proppants comprising (a) a particulate substrate having an external surface and (b) from approximately 0.001% to approximately 75% by volume of a material having electromagnetic properties which change under a mechanical stress; emplacing said blend of proppants in a fracture in said downhole environment, whereupon said composite proppants become subjected to the closure stress of said fracture, resulting in changes of electromagnetic properties of said composite proppants; and measuring changes in said electromagnetic properties by means of any suitable technique to track and monitor the locations of said proppants.
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27. A composite proppant composition, comprising:
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a thermoset particulate substrate, comprising a terpolymer of styrene, ethylvinylbenzene, and divinylbenzene; and from approximately 0.001% to approximately 75% by volume of a coating material placed on said thermoset particulate substrate, where said coating material is selected from the group consisting of lead zirconate titanate (PZT), barium titanate, Terfenol-D, Samfenol, Galfenol, or mixtures thereof. - View Dependent Claims (28, 29, 30, 31, 32)
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Specification