detailed programme - SIMS - Scandinavian Simulation Society

Abstract: Modeling of two phase flow is complex due to co-existence of
turbulence effects and moving boundaries between the phases and the velocity
difference between the two phases (gas and liquid). There are methods to
evaluate the flow regimes but they depend on transport properties of the two
phases, pipe roughness, mass, volume fraction in the pipe, and velocity ratio
between the two phases. The velocity ratio is called the slip ratio and there is no
simple way to evaluate it (Zhao, 2005).
The idea of this project is to make a model for pressure drop in two phase flow in
a geothermal well, compare the results with measured data from Icelandic
Geothermal wells and fit the slip ratio to the data in effort to find out if there is a
slip ratio that can be applied consistently on different depths. The results will be
compared to known void fraction correlations such as Lockhart Martinelli,
Rouhani-Axelsson
ect.
One of the challenges in this project is to estimate the accuracy of the
measurements performed on the wells. The quality of data is questionable due to
time difference between pressure and mass flow measurements. Because of
these uncertainties it is possible to assume that using simple models such as the
homogenous model will give results within a certain margin of error and should
rather be used since the method is simpler and faster than more complicated
correlations.
Authors: Thora Hlin Thorisdottir
Organization: University of Iceland
Paper 10
Title: Development of a Coupled Geothermal Reservoir-Wellbore Simulator Using
Measured Wellhead Parameters and Inverse Analysis
Keyword: geothermal modeling, coupled reservoir-wellbore simulator,
measured, wellhead conditions, inverse analysis, parameter estimation
Abstract: With growing world-population and increasing environmental concerns,
the demand for renewable energy and sustainable use of resources is rising
steadily. Geothermal energy production can be sustained for decades and even
centuries. However, excessive production is often pursued, resulting in cooling of
rocks, reduced production capacity and finally depletion of geothermal reservoirs.
Over-exploitation is caused by poor resource management, involving inadequate
monitoring and data collection, insufficient understanding of geothermal systems
and unreliable modeling.
Modeling a geothermal power production requires simulating the behavior of the
reservoir, the flow in production and injection wells and the flow in the fluid
gathering pipe system. These three components are usually simulated individually
with suitable models, where output of one model is used as an input to the next.
Very few simulators model the complete geothermal system but attempts have
been made to link reservoir simulators to wellbore simulators. Coupling these
simulators allows for more accurate modeling of the geothermal system and
produces more credible simulation responses to production.
Most reservoirs are monitored by measuring bottomhole pressure in wells with
descending equipments and from that the drawdown in pressure is estimated.
This is a time consuming and expensive process which usually involves production
stop in producing geothermal wells. A method for simulating the drawdown in
pressure of a geothermal reservoir by easily obtained well-head parameters is