SPE Western Regional Meeting,
27-29 May 2010,
Anaheim, California, USA
The Moxa Arch Anticline is a regional-scale northwest-trending uplift in
western Wyoming and it has been chosen for CO2 capture and storage. The Nugget
Sandstone is a deep saline aquifer that has been a candidate for CO2 storage.
In this paper we compare the amount of mineral and solution trapping in
comparison with dynamic hysteresis trapping based on composi-tional simulation.
To the best of our knowledge this is the first paper to computationally assess
the chemical trapping in the Nugget formation and to compare these three
trapping mechanisms against each other.
Reaction-path and kinetic modeling of CO2–brine–mineral reactions in the Nugget
formation was investigated to probe the factors that affect capacity for CO2
chemical trapping. The solution and precipitation trapping of CO2 are functions
of tem-perature, pressure, CO2 fugacity and brine composition. The geochemical
simulation of this system was explored in order to assess how mineralogy might
change and the relative importance of mineral and solution trapping phenomena
through time. After 30 years, 0.06 g of CO2 per kg of reacted rock is
sequestered as mineral phases and solution trapping amounts to 0.11 g/kg rock.
In comparison, a recent computational study of the Rose Run sandstone, Ohio
indicates a much higher (30 times higher) mineral trapping capacity, mainly
because of the presence of glauconite as an iron source for siderite formation.
The total hysteresis trapping in our study is 0.14 g/kg rock based on
compositional simulation for the same period of time.
These results reveal that mineral trapping in the Nugget formation is not
significant but that total chemical trapping might be as high as 80% of
hysteresis trapping. Therefore, the contribution and importance of chemical
trapping in CO2 sequestration should be taken into account for assessment of
CO2 sequestration is becoming one of the hot topics cross all disciplines. Most
of countries in the world are spending large amount of money to investigate CO2
sequestration feasibility and shortcomings e.g. cap rock leakage. Underground
forma-tion became the target for CO2-sequestraion such as abundant oil and gas
fields, coal bed methane and saline aquifer. The saline aquifers have the
maximum capacity. For instance in North America, saline aquifers capacity is
8±4 Billion metric tons, around 94% of total capacity while the mature
hydrocarbon reservoirs has 4% of total capacity (DOE and NETL, Car-bon and
Sequestration Atlas for the USA and Canada, 2008). All saline aquifers which
have salinity above 10000 ppm are acceptable for CO2-sequestration based on
U.S. Environmental Protection Agency. There have been a lot of researches on
CO2-Sequestration in last decades all over the world; The Netherlands (Lohuis,
1993), Alberta basin, Canada (Bachu et al., 1994; Gunter et al., 2004; Cantucci
et al., 2009), North Sea (Korbol and Kaddour, 1995) and USA (Zerai et al.,
2006; Han et al., 2009).
Once CO2 is injected it might be trapped in different ways. Significant portion
of CO2 might be trapped beneath caprock if caprock integrity is not
compromised. CO2 can be dissolve in water which also donated as solubility
trapping and also it might hydraulically trapped (hysteric trapping) and/or it
might react with a rock and produce carbonate minerals (mineral trapping).
Mineral trapping is the most stable trapping mechanism and there are a few
studies examine the reaction of CO2 with host rock. These studies are mostly
done by geologist while engineers have generally probe the other trapping
mechan-isms. In fact, there is not robust interdisciplinary study that combines
these two main disciplines and compares them. Howev-er, Nghiem (2009) simulated
the trapping mechanisms with GEM software (CMG package).