Long-term assessment of geochemical reactivity of CO2 storage in highly saline aquifers: Application to Ketzin, In Salah and Snøhvit storage sites

Abstract

International audienceSaline aquifers are choice targets for geological storage of CO2because of their storage potential andbecause these formations are not suitable for other uses. Geochemical modeling is an interesting tool toassess the geochemical behavior of CO2in the saline aquifer, including its dissolution in the brine andits interactions with minerals. Two key parameters which determine the confidence one can have in theresults of geochemical modeling are tested in this paper: (i) the establishment of the conceptual model,including the selection of the primary and secondary minerals expected to react; and (ii) the activitymodel and the associated thermodynamic databases to calculate the interaction energies within thesaline solution. In this study, we performed an analysis of a large set of CO2storage natural analogs, whichmakes it possible to identify the minerals that are likely to precipitate and dissolve during CO2-brine-rockinteractions. Interestingly, this analysis indicates a strong dependence of Dawsonite precipitation on theinitial sandstone mineralogy. Dawsonite can precipitate in lithic and feldspar rich sandstones but wasnot observed in quartz rich sandstones. These observations on mineral reactivity are used to establishreactivity conceptual models for three CO2storage case-studies in saline sandstone aquifers (Ketzin, InSalah and Snøhvit) and a methodology is proposed to evaluate the long-term geochemical reactivityof these saline aquifers as a result of CO2injection. Noticeable differences are obtained between thecase-studies as a function of the initial mineralogy and chemical conditions in the sandstones, whichhighlight that CO2mineral trapping can take place in a given storage site but can be almost absent inother storage sites. Regarding the activity model and the database, the Pitzer interaction model is rarelyused for simulating CO2geochemical behavior in saline aquifers despite the fact that more conventionallyused activity models are not valid for such salinities. A comparison between calculated mineral solubilityevolution with salinity versus experimental data is performed here using both B-dot and Pitzer activitymodels as well as six different databases. This comparison exercise shows that chemical interactionswithin saline solutions can only be reproduced using the Pitzer model, even though Pitzer databasesare still incomplete or are not coherent for a wide range of chemical species and temperatures. Thegeochemical simulations of CO2injection in Ketzin, In Salah and Snøhvit saline aquifers give divergentresults using different activity models and databases. A high uncertainty on the simulation results is thenlinked to the database choice and this study clearly stresses the need for a Pitzer database that can beconfidently used in all physical/chemical conditions found in deep sedimentary aquifers

Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

“…This approach involves the direct injection of captured CO 2 into compatible deep saline formations for long-term storage (Bachu and Adams 2003;IPCC 2005;Michael et al 2010;Rosenbauer and Thomas 2010;Chasset et al 2011;Hatzignatiou et al 2011;Kolenković et al 2013;Ran and Zohar 2013;Trémosa et al 2014). The density of supercritical CO 2 is lower than that of ambient saline water and this can lead to the migration of a CO 2 gaseous phase plume upward because of the buoyancy-driven force.…”

Influence of geochemical processes on the geomechanical response of the overburden due to CO2 storage in saline aquifers

“…Some of the industrial-scale projects which involve CO 2 injection in deep saline aquifers include the Sleipner project in the North Sea (Arts et al, 2008;Chadwick et al, 2004;Torp and Gale, 2004), the In Salah project in Algeria (Iding and Ringrose, 2009;Morris et al, 2011;Rutqvist et al, 2009;Torp and Gale, 2004), the Gorgon project in Australia (Hosa et al, 2011;Michael et al, 2010), the Snøhvit project in Norway (Eiken et al, 2011;Tremosa et al, 2014), and the Illinois Basin Decatur project in the Midwest region of the United States (Barnes et al, 2009;Bowen et al, 2011;Leetaru and McBride, 2009;Medina et al, 2011;Person et al, 2010). A few of these saline aquifers are reported to have large storage capacities exceeding 100 Mega tonnes (Hosa et al, 2011;Medina et al, each layer of the formation at the corresponding formation temperature.…”

Effects of H2S injection on the CO2-brine-sandstone interaction under 21 MPa and 70 °C

“…Potential geological reservoirs for CCS are depleted gas and oil reservoir, unmineable coal seam formations and deep saline aquifers (Wang et al, 2013;Zhu et al, 2013, Trémosa et al, 2014. Particularly, deep saline aquifers are preferred and well-documented due to its large storage capacity, ubiquity, and potential for carbonate mineral trapping (Rosenbauer et al, 2005, Ketzer et al, 2009, Trémosa et al, 2014.…”

“…Potential geological reservoirs for CCS are depleted gas and oil reservoir, unmineable coal seam formations and deep saline aquifers (Wang et al, 2013;Zhu et al, 2013, Trémosa et al, 2014. Particularly, deep saline aquifers are preferred and well-documented due to its large storage capacity, ubiquity, and potential for carbonate mineral trapping (Rosenbauer et al, 2005, Ketzer et al, 2009, Trémosa et al, 2014. As such, considerable experimental and modelling work has been performed to evaluate the chemical interactions of CO 2 with brine and host rocks (Shafeen et al, 2004, Oelkers andSchott, 2005;Xu et al, 2006, de Orte et al, 2014.…”