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Power density distribution in subsurface fractures due to an energized steel well-casing source


Robust in situ power harvesting underlies the realization of embedded wireless sensors for monitoring the physicochemical state of subsurface engineered structures and environments. The use of electromagnetic (EM) contrast agents in hydraulically fractured reservoirs, in coordination with completion design of wells, offers a way to transmit energy to remotely charge distributed sensors and interrogate fracture width, extent, and fracture-stage cross-communication. The quantification of available power in fracture networks due to energized steel-cased wells is crucial for such sensor designs; however, this has not been clarified via numerical modeling in the limit of Direct Current (DC). This paper presents a numerical modeling study to determine the EM characteristics of a subsurface system that is based on a highly instrumented field observatory. We use those realistic field scenarios incorporating geometry and material properties of contrast agents, the wellbore, and the surrounding geologic environment to estimate volumetric power density near the wellbore and within hydraulic fractures. The numerical modeling results indicate that the highest power densities are mainly focused around the wellbore excited by a point current source and the fracture boundary. Using DC excitation, the highest power density in the fracture is at the fracture tip. The relatively high-power density on the order of tens of mW/m3 at the vicinity of the wellbore and at fracture tips suggests that remote charging of sensor devices may be readily possible. Simulation results also show that the region of the highest power density can be significantly increased when the EM source is located inside a conductive fracture, which may lead to a promising deployment strategy for embedded micro-sensors in geologic formations.

ISSN: 1083-1363
EISSN: 1943-2658
Serial Title: Journal of Environmental & Engineering Geophysics
Serial Volume: 24
Serial Issue: 2
Title: Power density distribution in subsurface fractures due to an energized steel well-casing source
Affiliation: Sandia National Laboratories, Geophysics Department, Albuquerque, NM, United States
Pages: 285-297
Published: 201906
Text Language: English
Publisher: Environmental and Engineering Geophysical Society, Englewood, CO, United States
References: 17
Accession Number: 2019-082636
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: University of Texas at Austin, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, copyright, Environmental & Engineering Geophysical Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201944
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