Time-Dependent Consolidation in Porous Geomaterials at In Situ Conditions of Temperature and Pressure

Journal Article · 23 July 2018 · Journal of Geophysical Research. Solid Earth

DOI: https://doi.org/10.1029/2017JB015097 · OSTI ID:1472260

Choens, R. C.  ^[1]; Chester, F. M.  ^[2]

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1. Texas A & M Univ., College Station, TX (United States). Center for Tectonophysics. Dept. of Geology and Geophysics; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. Texas A & M Univ., College Station, TX (United States). Center for Tectonophysics. Dept. of Geology and Geophysics

Analysis of quartz sandstones shows that grain-scale crushing (fracture and rearrangement) and associated sealing of fractures contribute significantly to consolidation. The crushing strength (P*) for granular material is defined by laboratory experiments conducted at strain rates of 10^-4 to 10^-5 s^-1 and room temperature. Based on experiments, many sandstones would require burial depths in excess of the actual maximum burial depth to create observed microstructure and density. In this paper, we use experiments and soil mechanics principles to determine rate laws for brittle consolidation of fine-grained quartz sand to better estimate in situ failure conditions of porous geomaterials. Experiments were conducted on St. Peter sand utilizing different isostatic consolidation and creep load paths at temperatures to 200 °C and at strain rates of 10^-4 to 10^-10 s^-1. Experiment results are consistent with observed rate dependence of consolidation in soils, and P* for sand can be identified by the change in the dependence of consolidation rate with stress, allowing the extrapolation of P* determined in the laboratory to geologic rates and temperatures. Additionally, normalized P* values can be described by a polynomial function to quantify temperature, stress, and strain-rate relationships for the consolidation of porous geomaterials by subcritical cracking. At geologic loading rates, P* for fine-grained quartz sand is achieved within ~3-km burial depth, and thus, shear-enhanced compaction under nonisostatic stress can occur at even shallower depths. Finally, these results demonstrate that time and temperature effects must be considered for predicting the brittle consolidation of sediments in depositional basins, petroleum reservoirs, and engineering applications.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Center for Frontiers of Subsurface Energy Security (CFSES); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Texas A & M Univ., College Station, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003525; SC0001114
• OSTI ID: 1472260
• Alternate ID(s): OSTI ID: 1464865
• Report Number(s): SAND2018-9751J; 667631
• Journal Information: Journal of Geophysical Research. Solid Earth, Vol. 123, Issue 8; ISSN 2169-9313
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English