Title: Sodium diffusion in heterogeneous porous media: Connecting laboratory experiments and simulations

Abstract

Sodium has been suggested as a tracer for brine in reservoir formations where a significant amount of sodium ion is found mainly in the aqueous phase. Fortunately, the most abundant sodium isotope, ²³Na, is Nuclear Magnetic Resonance (NMR) active, making it possible to study the structure and dynamical properties of both bulk and pore confined fluid systems. We investigated the diffusion of key dissolved sodium species in bulk solution and porous media as a function of composition, ionic strength, and permeability of the carbonate samples using NMR relaxometry and pulsed-field gradient (PFG) NMR techniques. We use Indiana limestone as an example of natural porous media and water as a freely diffusible tracer and carrier. We demonstrate apparent diffusion measurement of sodium based on changes in spin–spin relaxation time (T₂) signal in pore confinement. The diffusion rate of sodium decreases with increasing counter-ion size. This effect is greater at higher ionic strengths and lower chemical potentials in porous media. The reactive transport code, CrunchFlow, was used to complement the NMR experiments to simulate diffusion behavior in porous media. Combining these two methods provides a powerful approach to estimating effective diffusion coefficients in heterogeneous matrices. The modeling considers the influence of physicalmore » properties (porosity and tortuosity) and chemical properties (geochemical composition and chemical gradients). The results presented in this work highlight the advantage of measuring apparent diffusivity using NMR T₂ relaxometry in conjunction with numerical simulation to derive effective diffusivity and the corresponding matrix properties (i.e., tortuosity) of the system.« less

Authors:

Hwang, Bohyun  ^[1];

• Search DOE PAGES for author "Hwang, Bohyun"
• Search DOE PAGES for ORCID "0000-0003-4788-3982"

Srivastava, Deepansh J.  ^[1];

• Search DOE PAGES for author "Srivastava, Deepansh J."
• Search DOE PAGES for ORCID "0000-0003-1341-2197"

Deng, Hang  ^[2];

• Search DOE PAGES for author "Deng, Hang"
• Search DOE PAGES for ORCID "0000-0001-5784-996X"

Grandinetti, Philip J. ^[1]; Cole, David R. ^[1]

---

+ Show Author Affiliations

1. The Ohio State Univ., Columbus, OH (United States)
2. Peking Univ., Beijing (China)

Publication Date:

Wed Sep 28 00:00:00 EDT 2022

Research Org.:

The Ohio State Univ., Columbus, OH (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1903218

Alternate Identifier(s):

OSTI ID: 1960663

Grant/Contract Number:  

SC0006878

Resource Type:

Accepted Manuscript

Journal Name:

Geochimica et Cosmochimica Acta

Additional Journal Information:

Journal Volume: 338; Journal ID: ISSN 0016-7037

Publisher:

Elsevier; The Geochemical Society; The Meteoritical Society

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; diffusion; solute transport; sodium; Indiana limestone; porous media; NMR; Crunchflow