Methods of improving C02 Sequestration in Saline Aquifer by surface treatment of injected C02

Sequestration of C02 in geologic formations will be part of substantive
campaign to mitigate greenhouse gas (C02) emissions. The risk of leakage from the
target formation due to natural and artificial pathways such as fractures, and fault are
important challenges in geological storage of C02• The leakage arises mainly from the
buoyancy of free-phase mobile C02 (gas or supercritical fluid). The best way for C02 to
be sequestered permanently is by mineralization of C02 and solubility trapping of COz
naturally in the aquifer. Those two processes take a long period of time estimated to
start in 10+ years of time. Alternatives of dissolution of COz prior to injection have
been come up to mitigate risk of leakage during period of the C02 to permanently
naturally sequester.
In this paper, the author investigates a conceptual process in which C02 is
dissolved with chemical prior to injection into the saline formations. As the C02-laden
chemical is denser than native brine containing no C02, it will eliminate the risk of
buoyancy-driven leakage. Several chemicals have been chosen namely Amine solution
(Monoethanolamine and Diethanolamine), Potassium Carbonate and Propylene
Carbonate. Using Aspen Hysys, products from the mixture of COz and chemicals are
evaluated for their properties. The author then investigates and compared the different
product properties. Main properties for evaluation of the products are the density. By
contrasting the injection strategy, the author chose the best injection strategy. In theory,
the injected C02 will mineralize with native rocks and sequestered permanently. Native
saline density of l.lg/cm3 is use for comparing the treated chemical.
Although this alternative may result in higher costs compared to standard
injection strategy, surface dissolution of C02 with chemical may be attractive where the
costs of monitoring or insuring against buoyancy-driven C02 leakage may exceed the
additional cost incurred. The benefit would be to decrease the risk of C02 leakage and
potential harm of environment and people.