Abstract
Our research objective is to understand the influence of geochemistry on the fracture behavior of organic-rich shale at multiple length-scales. Despite an increasing focus on the fracture behavior of organic-rich shale, the relationships between geochemistry and fracture behavior remain unclear and there is a scarcity of experimental data available. To this end, we carry out 59 mesoscale scratch-based fracture tests on 14 specimens extracted from 7 major gas shale plays both in the USA and in France. Post-scratch testing imaging reveals fractures with a small crack width of about 411–660 nm. The fracture toughness is evaluated using the energetic size effect law, which is extended to generic axisymmetric probes. A nonlinear anisotropic and multiscale fracture behavior is observed. In addition, a positive correlation is found between the fracture toughness and the presence of kerogen, clay and calcite. Moreover, the geochemistry is found to influence the timescale and the regime of propagation of the hydraulic fracture at the macroscopic length-scale. In particular, shale systems rich in total organic content, clay and calcite are more likely to exhibit high values of the fluid lag and a low hydraulic crack width. Our findings highlight the need for advanced constitutive models for organic-rich shale systems and advanced hydraulic fracturing solutions that can fully integrate the complex fracture response of organic-rich shale materials.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1129-1142 |
| Number of pages | 14 |
| Journal | Acta Geotechnica |
| Volume | 14 |
| Issue number | 4 |
| DOIs | |
| State | Published - Aug 1 2019 |
Funding
This work was supported as part of the Center of Geological Storage of CO 2 , an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Data for this project were provided, in part, by work supported by the U.S. Department of Energy under Award Number DE-FC26-05NT42588 and the Illinois Department of Commerce and Economic Opportunity. The X-ray diffraction analysis and kerogen content measurements were carried out at the Illinois State Geological Survey XRD Lab. The nanostructural analysis tests were performed in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois at Urbana-Champaign. The Woodford shale specimens were provided by the Poromechanics Institute at the University of Oklahoma. The Antrim and Niobrara specimens were provided by the MIT X-Shale project. The Toarcian specimens were provided by the Total Scientific and Technical Center, Pau, France. The Marcellus specimens were provided by the Department of Earth and Planetary Sciences at Northwestern University. This work was supported as part of the Center of Geological Storage of CO2 , an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Data for this project were provided, in part, by work supported by the U.S. Department of Energy under Award Number DE-FC26-05NT42588 and the Illinois Department of Commerce and Economic Opportunity. The X-ray diffraction analysis and kerogen content measurements were carried out at the Illinois State Geological Survey XRD Lab. The nanostructural analysis tests were?performed in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois at Urbana-Champaign. The Woodford shale specimens were provided by the Poromechanics Institute at the University of Oklahoma. The Antrim and Niobrara specimens were provided by the MIT X-Shale project. The Toarcian specimens were provided by the Total Scientific and Technical Center, Pau, France. The Marcellus specimens were provided by the Department of Earth and Planetary Sciences at Northwestern University.
Keywords
- Fracture
- Geochemistry
- Hydraulic Fracturing
- Organic-rich shale
- Scratch test
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology
- Earth and Planetary Sciences (miscellaneous)