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460
DOI 10.1007/s12182-014-0362-1
SAFARZADEH Mohammad Amin and MOTAHHARI Seyyed Mahdia
Research Institute of Petroleum Industry, Tehran, Iran
© China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg 2014
Abstract:
Climate researchers have observed that the carbon dioxide (CO
2
) concentration in the
atmosphere have been growing significantly over the past century. CO
2
from energy represents about
75% of the greenhouse gas (GHG) emissions for Annex B (Developed) countries, and over 60% of
global emissions. Because of impermeable cap rocks hydrocarbon reservoirs are able to sequester CO
2
.
In addition, due to high-demand for oil worldwide, injection of CO
2
is a useful way to enhance oil
production. Hence, applying an efcient method to co-optimize CO
2
storage and oil production is vital.
Lack of suitable optimization techniques in the past led most multi-objective optimization problems
to be tackled in the same way as a single objective optimization issue. However, there are some basic
differences between the multi and single objective optimization methods. In this study, by using a non-
dominated sorting genetic algorithm (NSGA-II) for an oil reservoir, some appropriate scenarios are
proposed based on simultaneous gas storage and enhanced oil recovery optimization. The advantages
of this method allow us to amend production scenarios after implementing the optimization process, by
regarding the variation of economic parameters such as oil price and CO
2
tax. This leads to reduced risks
and time duration of making new decisions based on upcoming situations.
Key words:
Greenhouse gas emission, carbon dioxide, enhanced oil recovery, multi-objective
optimization, decision making
Co-optimization of carbon dioxide storage and
enhanced oil recovery in oil reservoirs using a
multi-objective genetic algorithm (NSGA-II)
*Corresponding author. email: safarzadehma@ripi.ir
Received October 13, 2013
Convention on Climate change called for developed countries
to reduce emissions of greenhouse gases (GHG) by average
of 5.2%, below the 1990 levels by 2008 to 2012. Since clients
are interested in saving money, any emission reduction
option, such as underground storage that costs less than the
tax that would otherwise be paid, will be adopted (McKitrick,
2013).
Geological CO
2
storage as the only effective option to
mitigate CO
2
emissions has been considered since 1990s
and has been implemented in large scale for the first time
in Norway. The Sleipner project is the first commercial
CO
2
injection into a deep saline aquifer (US Department
of Energy, 2010). Because of impermeable cap rocks,
hydrocarbon reservoirs have proper conditions for storage
of CO
2
. On the other hand, injection of CO
2
is implemented
practically to improve oil recovery, and it is more benecial
in oil reservoirs than in gas ones. The main mechanisms
in CO
2
enhanced oil recovery (CO
2
EOR) are: decreasing
oil-water interfacial tension and CO
2
-oil surface tension;
dissolving CO
2
in the oil phase; evaporation of intermediate
oil components; decrease in in-situ oil viscosity and density;
improvement of reservoir permeability and pressure control
in the near production well zone. The rst commercial CO
2
injection was accomplished in 1972 by Chevron Company in
Pet.Sci.(2014)11:460-468
1 Introduction
The CO
2
concentration trend mostly reflects energy-
related activities that, over the past decade, are determined
by economic growth, generally in developing countries. The
2012 CO
2
concentration of 394 ppm is about 40% higher than
that in the mid-1800s, with an average growth of two ppm/
year in the last ten years (Olivier and Muntean, 2013). Despite
the growth of non-fossil energy, considered as non-emission,
the share of fossil fuels in the worldwide energy supply is
almost unchanged over the past 40 years. Climate researchers
have found that CO
2
concentrations in the atmosphere have
been growing significantly over the past century, compared
to the rather steady level of the pre-industrial period (Van der
Hoeven, 2013). The International Panel on Climate Change
(IPCC) predicts that the CO
2
concentration in the atmosphere
may reach 570 ppm by the year 2100, resulting in a rise of
mean global temperature and an increase in mean sea level
(Javaheri et al, 2009; U S Environmental Protection Agency,
2009).
The Kyoto Protocol of the United Nations Framework