Heterogeneous multiphase flow properties of volcanic rocks and implications for noble gas transport from underground nuclear explosions
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Geomechanics
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Applied Systems Analysis and Research
- California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States). Dept. of Natural Resources Management and Environmental Sciences
Of interest to the Underground Nuclear Explosion Signatures Experiment are patterns and timing of explosion-generated noble gases that reach the land surface. The impact of potentially simultaneous flow of water and gas on noble gas transport in heterogeneous fractured rock is a current scientific knowledge gap. This article presents field and laboratory data to constrain and justify a triple continua conceptual model with multimodal multiphase fluid flow constitutive equations that represents host rock matrix, natural fractures, and induced fractures from past underground nuclear explosions (UNEs) at Aqueduct and Pahute Mesas, Nevada National Security Site, Nevada, USA. Capillary pressure from mercury intrusion and direct air–water measurements on volcanic tuff core samples exhibit extreme spatial heterogeneity (i.e., variation over multiple orders of magnitude). Petrographic observations indicate that heterogeneity derives from multimodal pore structures in ash-flow tuff components and post-depositional alteration processes. Comparisons of pre- and post-UNE samples reveal different pore size distributions that are due in part to microfractures. Capillary pressure relationships require a multimodal van Genuchten (VG) constitutive model to best fit the data. Relative permeability estimations based on unimodal VG fits to capillary pressure can be different from those based on bimodal VG fits, implying the choice of unimodal vs. bimodal fits may greatly affect flow and transport predictions of noble gas signatures. The range in measured capillary pressure and predicted relative permeability curves for a given lithology and between lithologies highlights the need for future modeling to consider spatially distributed properties.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). WIPP Site
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1810392
- Report Number(s):
- SAND--2021-3607J; 697266
- Journal Information:
- Vadose Zone Journal, Journal Name: Vadose Zone Journal Journal Issue: 3 Vol. 20; ISSN 1539-1663
- Publisher:
- Soil Science Society of AmericaCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Data supporting the article titled "Heterogeneous Multiphase Flow Properties of Volcanic Rocks and Implications for Noble Gas Transport from Underground Nuclear Explosions"
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dataset | January 2021 |
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