Title: High-stress triaxial direct-shear fracturing of Utica shale and in situ X-ray microtomography with permeability measurement

Abstract

The challenge of characterizing subsurface fluid flow has motivated extensive laboratory studies, yet fluid flow through rock specimens in which fractures are created and maintained at high-stress conditions remains underinvestigated at this time. The studies of this type that do exist do not include in situ fracture geometry measurements acquired at stressed conditions, which would be beneficial for interpreting the flow behavior. Therefore, this study investigates the apparent permeability induced by direct-shear fracture stimulation through Utica shale (a shale gas resource and potential caprock material) at high triaxial stress confinement and for the first time relates these values to simultaneously acquired in situ X-ray radiography and microtomography images. Change in fracture geometry and apparent permeability was also investigated at additional reduced stress states. Finite element and combined finite-discrete element modeling were used to evaluate the in situ observed fracturing process. Results from this study indicate that the increase in apparent permeability through fractures created at high-stress (22.2 MPa) was minimal relative to the intact rock (less than 1 order of magnitude increase), while fractures created at low stress (3.4 MPa) were significantly more permeable (2 to 4 orders of magnitude increase). Here, this study demonstrates the benefit of in situmore » X-ray observation coupled with apparent permeability measurement to analyze fracture creation in the subsurface. Our results show that the permeability induced by fractures through shale at high stress can be minor and therefore favorable in application to CO₂ sequestration caprock integrity but unfavorable for hydrocarbon recovery from unconventional reservoirs.« less

Authors:

Frash, Luke P.  ^[1];

• Search DOE PAGES for author "Frash, Luke P."
• Search DOE PAGES for ORCID "0000-0002-5424-4698"

Carey, J. William  ^[1];

• Search DOE PAGES for author "Carey, J. William"
• Search DOE PAGES for ORCID "0000-0001-8488-2925"

Lei, Zhou ^[1]; Rougier, Esteban ^[1]; Ickes, Timothy ^[1]; Viswanathan, Hari S.  ^[1]

• Search DOE PAGES for author "Viswanathan, Hari S."
• Search DOE PAGES for ORCID "0000-0002-1178-9647"

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Sat Jul 09 00:00:00 EDT 2016

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1532704

Alternate Identifier(s):

OSTI ID: 1402279

Report Number(s):

LA-UR-15-27278
Journal ID: ISSN 2169-9313

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Solid Earth

Additional Journal Information:

Journal Volume: 121; Journal Issue: 7; Journal ID: ISSN 2169-9313

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Energy Sciences; X-ray Computed Tomography; Utica; Shale; Fracture; Permeability; Microtomography; CO2 sequestration; Hydraulic Fracturing; Shear Stimulation; Caprock; FDEM; Induced Seismicity