detailed programme - SIMS - Scandinavian Simulation Society

in geothermal modeling. These wells along with other observations, indicate that
the roots of the geothermal systems in the volcanic active zone in Iceland are at
shallower depths that previously believed. Thus, the structure of existing
numerical models have to be reconsidered and heat sources have to be included
into the models.
Including the heat sources into the models does also challenge the practice of
assuming that the geothermal system is in a steady state or natural state, since
intrusions in the roots of volcanoes are not steady phenomena. Periods of high
intrusion activity are known in volcanic systems in Iceland. In an improved
modeling scheme the heat sources should not only be included in the model along
with the entire water circulation the should also be time dependent.
Authors: Gunnar Gunnarsson, Edda S.P. Aradóttir
Organization: Orkuveita Reykjavíkur
Paper 19
Title: Modeling Two Phase Flow and Phase Change in Liquid Dominated
Hydrothermal Systems
Keyword: reservoir modeling, two-phase flow, phase change, porous medium,
scientific computing
Abstract: A new modeling approach of two phase fluid flow in geothermal
reservoirs is presented in the paper. The flow is assumed to be liquid dominated,
but vapor will travel alongside the liquid at the same speed if present, which is
common for hydrothermal systems. The model also accounts for phase changes,
but they give rise to numerical instabilities due to the discontinuities in physical
properties. An analysis is presented here on how to treat those instabilities in
order to ensure a stable solution. The entire problem is then formulated and
solved by using a highly customizable set of C++ libraries and tools, collectively
named OpenFOAM, along with an implementation of the IAPWS-IF97 standard for
the properties of steam and water.
Preliminary results from a more general modeling work on hydrothermal systems
are presented in simple case studies, showing the basic abilites of the
programming platform to solve large three dimensional problems for flow in
porous media. It is concluded that the modeling framework is both flexible and
efficient, and an added benefit is that it is under constant improvement by a large
group of developers and incorporates cutting edge technologies in numerical
analysis for mathematical modeling.
Authors: Larus Thorvaldsson, Halldor Palsson
Organization: University of Iceland
Paper 16
Title: Estimation of slip ratio correlations for two phase flow in Icelandic
Geothermal Wells
Keyword: Two phase flow, Slip ratio, Pressure drop, Geothermal well