Studies of smectite membrane behavior: Electrokinetic, osmotic, and isotopic fractionation processes at elevated pressures

Journal Article · Tue Mar 01 00:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90333-X· OSTI ID:5181037

Demir, I ^[1]

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1. Univ. of Illinois, Urbana (USA)

A 1.087 m NaCl brine was forced through a clay membrane 0.32 cm thick at 294 {plus minus} 1{degree}K. The clay membrane was made by compacting the 0.5 to 2.0 micron size fraction of Cheto montmorillonite from Chambers, Arizona. A confining pressure of 34.5 MPa (5,000 psi) and a mean hydraulic pressure of 15.9 MPa (2,300 psi) were chosen to simulate a depth of about 1.5 km (5,000 ft) in sedimentary basins. Differential hydraulic pressure across the clay was 13.8 MPa (2,000 psi). This differential hydraulic pressure setting was disturbed for only brief intervals during the experimental run. Hydraulic flow rate, electrical conductance, electrical potential across the clay, electroosmotic flow rate, and the chemical composition of the brine were determined periodically until constancy of both effluent chemical composition and electrical potential across the clay was achieved. Then, osmotic flow rate and stable oxygen isotopic compositions of both input and effluent reservoirs were determined before the run was terminated. The experimental results conform to the predictions of nonequilibrium thermodynamics under these simulated subsurface conditions. The electroviscous effect caused a significant reduction in the hydraulic flow rate but did not disturb the linearity between the flow rate and differential hydraulic pressure. Osmotic and electroosmotic effects may be responsible for driving large amounts of cross-formational subsurface fluid flow in nature. A measured {sup 18}O fractionation of 0.25{per thousand} compares well with published field and laboratory data.

• OSTI ID: 5181037
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:3; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
SMECTITE
ELECTRODYNAMICS
MEMBRANES
PERMEABILITY
ARIZONA
BENCH-SCALE EXPERIMENTS
BRINES
FLOW RATE
GEOCHEMISTRY
ISOTOPE RATIO
MEMBRANE PORES
MEMBRANE TRANSPORT
OSMOSIS
OXYGEN ISOTOPES
PRESSURE EFFECTS
SEDIMENTARY BASINS
SODIUM CHLORIDES
THERMODYNAMIC PROPERTIES
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CLAYS
DIFFUSION
FEDERAL REGION IX
GEOLOGIC STRUCTURES
HALIDES
HALOGEN COMPOUNDS
ISOTOPES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SODIUM COMPOUNDS
USA
580000* - Geosciences