Optic Imaging of Two-Phase-Flow Behavior in 1D Nanoscale Channels

Abstract

Gas in tight sand and shale exists in underground reservoirs with microdarcy (µd) or even nanodarcy (nd) permeability ranges; these reservoirs are characterized by small pore throats and crack-like interconnections between pores. The size of the pore throats in shale may differ from the size of the saturating-fluid molecules by only slightly more than one order of magnitude. The physics of fluid flow in these rocks, with measured permeability in the nanodarcy range, is poorly understood. Knowing the fluid-flow behavior in the nanorange channels is of major importance for stimulation design, gas-production optimization, and calculations of the relative permeability of gas in tight shale-gas systems. In this work, a laboratory-on-chip approach for direct visualization of the fluid-flow behavior in nanochannels was developed with an advanced epi-fluorescence microscopy method combined with a nanofluidic chip. Displacements of two-phase flow in 100-nmdepth slit-like channels were reported. Specifically, the two-phase gas-slip effect was investigated. Under experimental conditions, the gas-slippage factor increased as the water saturation increased. The two-phase flow mechanism in 1D nanoscale slit-like channels was proposed and proved by the flow-pattern images. The results are crucial for permeability measurement and understanding fluidflow behavior for unconventional shale-gas systems with nanoscale pores.

Department(s)

Geosciences and Geological and Petroleum Engineering

Second Department

Chemistry

Keywords and Phrases

Flow behaviors; Nanoscale channels

International Standard Serial Number (ISSN)

1086-055X

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 Society of Petroleum Engineers (SPE), All rights reserved.

Publication Date

01 Oct 2014

Link to Full Text

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