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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water resources and hydroinformatics : Numerical model for napl migration in double-porosity subsurface systems
Numerical model for napl migration in double-porosity subsurface systems
Author : SU KONG NGIEN(1) & TAN LIT KEN(2)
ABSTRACT
The double-porosity concept has been successfully applied by many researchers to simulate fluid flow in oil reservoirs
over the past few decades. These oil reservoirs were typically considered to be made of fractured or fissured rock, hence
the usance of the double-porosity concept. Nonetheless, double-porosity may also exist in soil either through soil
aggregation, or through soil features such as wormholes, cracks and root holes. These attributes in soil that cause the
occurrence of double-porosity are also known as secondary porosity features and are akin to the reservoir rock fractures
or fissures. In the case of groundwater contamination, the occurrence of double-porosity in soil is highly influential since
immiscible fluids have been found to flow preferentially through the secondary porosity features. Ergo, a numerical
model for non-aqueous phase liquids (NAPL) migration in double-porosity groundwater systems was developed. This
model was modified from the conventional double-porosity model applied in the petroleum industry. The difference is
that while the standard double-porosity models usually simulate the fluid flows in both continua making up the doubleporosity
medium, the double-porosity model presented here focuses the modelling on the secondary porosity features in
the soil, therefore making it more pertinent in the context of groundwater contamination. In the modified model, the
phase saturations and relative permeabilities are expressed as functions of the capillary pressures. The resultant nonlinear
governing partial differential equations are solved using numerical methods. The problem is discretized spatially
using the Galerkinís weighted-residual finite element method whereas a fully implicit scheme is used for temporal
discretization. Verification of the developed model has been done against similar works in the open literature and the
preferential flow of NAPL through the secondary porosity features was validated.
File Size : 460,316 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water resources and hydroinformatics
Date Published : 20/08/2015
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