Chromatographic partitioning of impurities contained in a CO2 stream injected into a deep saline aquifer: Part 1. Effects of gas composition and in situ conditions

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

“…As seen in Figure 5.5 and 5.6, the H 2 S mass fraction in the supercritical fluid phase decreases progressively with distance from the injection well, with much lower values obtained at the leading edge of the gas plume. These results are consistent with observation reported by Bachu and Bennion, (2009) …”

“…Bachu and Bennion (2009) discussed unpublished information suggesting breakthough of CO 2 ahead of H 2 S at a producing well in a depleted gas reservoir. They subsequently confirmed this process by laboratory experiments (Bachu and Bennion, 2009) and numerical simulations ). Sensitivity studies conducted by these authors were helpful for identifying the factors that affect the breakthrough of H 2 S. However, their experimental and modeling work was for column-scale systems.…”

“…The chemical interactions of reservoir rock with CO 2 and co-contaminants such as H 2 S and SO 2 have been investigated by others through laboratory and modeling studies (e.g., Gunter et al, 2000 and2005;Knauss et al, 2005;Palandri and Kharaka, 2005a,b;Xu et al, 2007;Bachu and Bennion, 2009;Murphy et al, 2010). Geochemical and reactive transport modeling studies so far have been directed primarily towards reservoir rock, focusing on CO 2 and H 2 S sequestration reactions, as well as mineral alteration and pH buffering.…”

“…Laboratory work (Bachu and Bennion, 2009) has shown that gases contained in a CO 2 injection stream will chromatographically partition when in contact with the brine present in deep saline aquifers. As described in , chromatographic partitioning of various gases, when in contact with subsurface fluids, is not a new phenomenon.…”

“…The effect of co-injected H 2 S on mineral trapping of CO 2 and mineralogical alteration of reservoir host rocks has been studied previously (Gunter et al, 2000 and2005;Knauss et al, 2005;Xu et al, 2007), but with focus on the geochemical evolution in the storage formation at relatively high temperature and pressure (T>70 o C, P>150 bar). The behavior of co-injected H 2 S along a leakage pathway, while affected by chromatographic partitioning between CO 2 and water (Bachu and Bennion, 2009;, and/or the potential consequence of CO 2 plus H 2 S intruding into a shallow groundwater aquifer, have remained largely uninvestigated.…”