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Geofluids
Volume 2018, Article ID 5098283, 13 pages
https://doi.org/10.1155/2018/5098283
Research Article

Investigating Multiphase Flow Phenomena in Fine-Grained Reservoir Rocks: Insights from Using Ethane Permeability Measurements over a Range of Pore Pressures

Department of Earth, Ocean and Atmospheric Sciences, The University of British Columbia, 2020-2207 Main Mall, Vancouver, BC, Canada V6T 1Z4

Correspondence should be addressed to Eric Aidan Letham; moc.liamg@mahtelae

Received 19 September 2017; Revised 13 December 2017; Accepted 3 January 2018; Published 7 March 2018

Academic Editor: Tongqiang Xia

Copyright © 2018 Eric Aidan Letham and Robert Marc Bustin. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The ability to quantify effective permeability at the various fluid saturations and stress states experienced during production from shale oil and shale gas reservoirs is required for efficient exploitation of the resources, but to date experimental challenges prevent measurement of the effective permeability of these materials over a range of fluid saturations. To work towards overcoming these challenges, we measured effective permeability of a suite of gas shales to gaseous ethane over a range of pore pressures up to the saturated vapour pressure. Liquid/semiliquid ethane saturation increases due to adsorption and capillary condensation with increasing pore pressure resulting in decreasing effective permeability to ethane gas. By how much effective permeability to ethane gas decreases with adsorption and capillary condensation depends on the pore size distribution of each sample and the stress state that effective permeability is measured at. Effective permeability decreases more at higher stress states because the pores are smaller at higher stress states. The largest effective permeability drops occur in samples with dominant pore sizes in the mesopore range. These pores are completely blocked due to capillary condensation at pore pressures near the saturated vapour pressure of ethane. Blockage of these pores cuts off the main fluid flow pathways in the rock, thereby drastically decreasing effective permeability to ethane gas.