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Title: Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures

Here, we generate a wide range of models of proppant-packed fractures using discrete element simulations, and measure fracture conductivity using finite element flow simulations. This allows for a controlled computational study of proppant structure and its relationship to fracture conductivity and stress in the proppant pack. For homogeneous multi-layered packings, we observe the expected increase in fracture conductivity with increasing fracture aperture, while the stress on the proppant pack remains nearly constant. This is consistent with the expected behavior in conventional proppant-packed fractures, but the present work offers a novel quantitative analysis with an explicit geometric representation of the proppant particles. In single-layered packings (i.e. proppant monolayers), there is a drastic increase in fracture conductivity as the proppant volume fraction decreases and open flow channels form. However, this also corresponds to a sharp increase in the mechanical stress on the proppant pack, as measured by the maximum normal stress relative to the side crushing strength of typical proppant particles. We also generate a variety of computational geometries that resemble highly heterogeneous proppant packings hypothesized to form during channel fracturing. In some cases, these heterogeneous packings show drastic improvements in conductivity with only moderate increase in the stress on the proppantmore » particles, suggesting that in certain applications these structures are indeed optimal. We also compare our computer-generated structures to micro computed tomography imaging of a manually fractured laboratory-scale shale specimen, and find reasonable agreement in the geometric characteristics.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Report Number(s):
SAND-2016-10770J
Journal ID: ISSN 1365-1609; 648593
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
International Journal of Rock Mechanics and Mining Sciences
Additional Journal Information:
Journal Volume: 100; Journal Issue: C; Journal ID: ISSN 1365-1609
Publisher:
Elsevier
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1421854

Bolintineanu, Dan S., Rao, Rekha R., Lechman, Jeremy B., Romero, Joseph A., Jove-Colon, Carlos F., Quintana, Enrico C., Bauer, Stephen J., and Ingraham, Mathew Duffy. Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures. United States: N. p., Web. doi:10.1016/j.ijrmms.2017.10.014.
Bolintineanu, Dan S., Rao, Rekha R., Lechman, Jeremy B., Romero, Joseph A., Jove-Colon, Carlos F., Quintana, Enrico C., Bauer, Stephen J., & Ingraham, Mathew Duffy. Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures. United States. doi:10.1016/j.ijrmms.2017.10.014.
Bolintineanu, Dan S., Rao, Rekha R., Lechman, Jeremy B., Romero, Joseph A., Jove-Colon, Carlos F., Quintana, Enrico C., Bauer, Stephen J., and Ingraham, Mathew Duffy. 2017. "Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures". United States. doi:10.1016/j.ijrmms.2017.10.014. https://www.osti.gov/servlets/purl/1421854.
@article{osti_1421854,
title = {Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures},
author = {Bolintineanu, Dan S. and Rao, Rekha R. and Lechman, Jeremy B. and Romero, Joseph A. and Jove-Colon, Carlos F. and Quintana, Enrico C. and Bauer, Stephen J. and Ingraham, Mathew Duffy},
abstractNote = {Here, we generate a wide range of models of proppant-packed fractures using discrete element simulations, and measure fracture conductivity using finite element flow simulations. This allows for a controlled computational study of proppant structure and its relationship to fracture conductivity and stress in the proppant pack. For homogeneous multi-layered packings, we observe the expected increase in fracture conductivity with increasing fracture aperture, while the stress on the proppant pack remains nearly constant. This is consistent with the expected behavior in conventional proppant-packed fractures, but the present work offers a novel quantitative analysis with an explicit geometric representation of the proppant particles. In single-layered packings (i.e. proppant monolayers), there is a drastic increase in fracture conductivity as the proppant volume fraction decreases and open flow channels form. However, this also corresponds to a sharp increase in the mechanical stress on the proppant pack, as measured by the maximum normal stress relative to the side crushing strength of typical proppant particles. We also generate a variety of computational geometries that resemble highly heterogeneous proppant packings hypothesized to form during channel fracturing. In some cases, these heterogeneous packings show drastic improvements in conductivity with only moderate increase in the stress on the proppant particles, suggesting that in certain applications these structures are indeed optimal. We also compare our computer-generated structures to micro computed tomography imaging of a manually fractured laboratory-scale shale specimen, and find reasonable agreement in the geometric characteristics.},
doi = {10.1016/j.ijrmms.2017.10.014},
journal = {International Journal of Rock Mechanics and Mining Sciences},
number = C,
volume = 100,
place = {United States},
year = {2017},
month = {11}
}