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ELECTRICALLY CONDUCTIVE PROPPANT COMPRISING CARBON NANOTUBES AND CARBON FIBERS

IP.com Disclosure Number: IPCOM000249103D
Publication Date: 2017-Feb-06
Document File: 7 page(s) / 231K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method whereby carbon nanotubes and/or carbon fibers are added to a conventional proppant to serve as a contrast agent to be used to map the extent of the proppant within a hydraulically fractured reservoir.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 34% of the total text.

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ELECTRICALLY CONDUCTIVE PROPPANT COMPRISING CARBON NANOTUBES AND CARBON FIBERS

Field

[0001] This disclosure relates to monitoring for hydraulic fracturing using electrically

conductive proppant to create a physical property contrast.

Summary

[0002] A method whereby carbon nanotubes and/or carbon fibers are added to a conventional

proppant to serve as a contrast agent to be used to map the extent of the proppant within a

hydraulically fractured reservoir.

[0003] Carbon nanotubes and carbon fibers have an electrical conductivity much larger than

conventional sand or ceramic proppant. By including them in combination with conventional or

altered proppant, a physical property contrast between the host reservoir rock and the propped

region of the fracture can be created. This contrast can then be imaged using electromagnetic (EM)

well-log measurements or a cross-well EM survey. The collected data can then be inverted or

interpreted to obtain information about the proppant distribution within the hydraulically fractured

reservoir.

Steps of the proposed method

1. Carbon nanotubes and/or carbon fibers are included in a proppant to be used for a hydraulic

fracture stimulation.

2. The altered proppant is pumped into the fractured reservoir during a fracturing job.

3. EM Well-log measurements or a cross-well electromagnetic survey is conducted.

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4. The collected data are interpreted and/or inverted to obtain information about the proppant

distribution within the reservoir.

[0004] Note that often, multiple fracture stages are performed on a single well. The proppant

containing carbon nanotubes and/or fibers may be used for multiple stages or a select number of

stages. If a cross-well survey is conducted, multiple wells will be required for the survey.

Detailed Description

[0005] In order to use geophysics to image the distribution of proppant within a hydraulically

fractured reservoir, the proppant must have physical properties that are distinct from the host

reservoir rock. In particular, for a cross-well electromagnetic (EM) survey or well-log, where a

time-varying electric or magnetic source acts to excite secondary currents the electrical

conductivity and/or magnetic permeability must be distinct from the host. This can be

accomplished by including particles with a high electrical conductivity or magnetic permeability

in the proppant.

[0006] Carbon nanotubes (CNTs) may be added to a sand or ceramic proppant to create a

contrast in electrical conductivity between the proppant and host reservoir rock. In order to

characterize the impact of the inclusion of carbon nanotubes on the conductivity of the propped

region of the fracture, effective medium approximations can be used, such as self-consistent

effective medium theory (Bruggeman, 1935). We consider the fractures to be filled with a three-

phase material, comprising fluid (3 S/m, similar to the conductivity of sea-water), conventional

sand or ceramic proppant (10-6 S/m) and carbon nanotubes (106...