Experimental evaluation of the impact of the interactions of CO₂‐SO₂, brine, and reservoir rock on petrophysical properties: A case study from the Ketzin test site, Germany

Abstract

[1] The objective of this study is to evaluate the impact of impure CO 2 on a possible CO 2 repository. Here we present experimental data on the simulation of the injection of pure CO 2 and CO 2 and cocontaminant SO 2 into a saline aquifer. Long-term exposure experiments with pure CO 2 reveal no significant changes in the petrophysical properties (electrical resistivity, elastic wave velocity, and permeability). In contrast, for the injection of CO 2 and cocontaminant SO 2 (1 vol %) we have observed significant and irreversible changes of all monitored physical parameters. On the one hand, the decrease of P wave velocity and the increase of electrical resistivity indicate a dissolution of some framework material. On the other hand, the decrease of permeability points to the mobilization and redistribution of fines. These data might be relevant for subsequent modeling and estimations about tolerable concentration limits regarding the contaminants of CO 2 to be stored.

Borehole seismic monitoring of CO2 storage within a saline aquifer at Ketzin, Germany

“…The effect of CO 2 injection on the P-wave and S-wave velocities of the Ketzin reservoir was investigated at laboratory scale by Kummerow and Spangenberg (2011). The experiments were carried out on a sample from the reservoir sandstone of the Stuttgart Formation which was cored from the well Ktzi 202 at 629 m below ground level.…”

“…The P-wave velocities v p show a hysteretic behaviour resulting from a relative rapid decrease of v p with decreasing brine saturation from 3.20 km/s to 2.69 km/s (16 %) and a hesitant increase of v p at brine imbibition. The P-wave velocity reaches its initial value after the sample is re-saturated with brine at the end of the experiment" (Kummerow and Spangenberg (2011)). (2011)).…”

“…The sample has a porosity of 28 %. "In thin sections the distribution of porosity is inhomogeneous with less porous lenticular clay layers and porous grain supported sandstone layers" (Kummerow and Spangenberg (2011)). To mimic reservoir conditions, the sample was saturated with a synthetic formation brine and the flow experiments were performed at the conditions of the Ketzin reservoir (p conf ining = 15 MPa, p pore = 7.5 MPa, T = 40 • C).…”

“…• Analyses of rock samples, gases and fluids from the subsurface (Muller et al (2009);Fischer et al (2010Fischer et al ( , 2011; Myrttinen et al (2010); Zemke et al (2010); Kummerow and Spangenberg (2011);Rempel et al (2011);Scherf et al (2011);Zimmer et al (2009Zimmer et al ( , 2011a). …”

“…Since there was no opportunity for a direct determination of water saturation of the sample during the experiments in the high-pressure cell, the water saturation was estimated from resistivity measurements. "Ultrasonic measurements were performed in the pulse transmission mode at a resonance frequency of 500 kHz" (Kummerow and Spangenberg (2011)). …”