Effect of CO2 on P- and S-wave velocities at seismic and ultrasonic frequencies

Agofack, Nicolaine; Lozovyi, Serhii; Bauer, Andreas

doi:10.1016/j.ijggc.2018.09.010

Cited by 7 publications

(9 citation statements)

References 27 publications

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“…A reduction of the undrained bulk modulus after exposure to CO 2 -brine was also reported [70]. The cause of this reduction in the experiment of Agofack et al [70] could be the combined effect of change in the microstructure due to chemical reactions and that of the compressibility of the pore fluid due to free CO 2 coming out of solution when the pore pressure decreased during the applied cycles [175].…”

Section: Shale Samples Exposed To Co 2 -Water or Co 2 -Brinementioning

confidence: 70%

“…Because the only changed parameter during the experiment is the exposure environment, its effect is better monitored. Some new experimental results using low-frequency measurements [175], which are not presented here, revealed that the Young's modulus of a Draupne shale sample exposed to CO 2 increased by around 2%, while its Poisson ratio remained roughly unchanged.…”

mentioning

confidence: 63%

“…Indeed, it has been demonstrated that free CO 2 can emerge from a solution within a sample if the test pressure is lower than the pressure at which the sample was saturated with CO 2 -rich brine. The presence of free CO 2 affects the compressibility of the pore fluid and the dynamic stiffness of the porous material [175]. These effects were not discussed in the experiments listed here and are not analyzed in this review.…”

mentioning

confidence: 98%

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Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

et al. 2020

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In carbon storage activities, and in shale oil and gas extraction (SOGE) with carbon dioxide (CO2) as stimulation fluid, CO2 comes into contact with shale rock and its pore fluid. As a reactive fluid, the injected CO2 displays a large potential to modify the shale’s chemical, physical, and mechanical properties, which need to be well studied and documented. The state of the art on shale–CO2 interactions published in several review articles does not exhaust all aspects of these interactions, such as changes in the mechanical, petrophysical, or petrochemical properties of shales. This review paper presents a characterization of shale rocks and reviews their possible interaction mechanisms with different phases of CO2. The effects of these interactions on petrophysical, chemical and mechanical properties are highlighted. In addition, a novel experimental approach is presented, developed and used by our team to investigate mechanical properties by exposing shale to different saturation fluids under controlled temperatures and pressures, without modifying the test exposure conditions prior to mechanical and acoustic measurements. This paper also underlines the major knowledge gaps that need to be filled in order to improve the safety and efficiency of SOGE and CO2 storage.

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Section: Shale Samples Exposed To Co 2 -Water or Co 2 -Brinementioning

confidence: 70%

mentioning

confidence: 63%

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confidence: 98%

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Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

et al. 2020

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“…Stress and pressure are controlled by an electromechanical frame (MTS Criterion C45 300 kN) and high-accuracy pumps (Vindum VP-Series), respectively. A CO 2 flow loop (described in Section 3.4) enabled CO 2 effects to be studied [44,45].…”

Section: Mechanical Measurementsmentioning

confidence: 99%

“…We present a method to monitor the mechanical responses of a specimen exposed to CO 2 over an elongated period of time using the forced-oscillation (FO) and pulse-transmission (PT) techniques. PT is the dominant dynamic technique but FO and resonant bar (RB) studies also exist albeit limited to sandstones exposed to CO 2 [40][41][42][43][44][45]. The novelty of our approach is that our specimen is exposed to three different fluids while confined under continuous stress, pressure, and temperature regimes.…”

Section: Introductionmentioning

confidence: 99%

On the Effect of CO2 on Seismic and Ultrasonic Properties: A Novel Shale Experiment

et al. 2021

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Carbon capture and storage (CCS) by geological sequestration comprises a permeable formation (reservoir) for CO2 storage topped by an impermeable formation (caprock). Time-lapse (4D) seismic is used to map CO2 movement in the subsurface: CO2 migration into the caprock might change its properties and thus impact its integrity. Simultaneous forced-oscillation and pulse-transmission measurements are combined to quantify Young’s modulus and Poisson’s ratio as well as P- and S-wave velocity changes in the absence and in the presence of CO2 at constant seismic and ultrasonic frequencies. This combination is the laboratory proxy to 4D seismic because rock properties are monitored over time. It also improves the understanding of frequency-dependent (dispersive) properties needed for comparing in-situ and laboratory measurements. To verify our method, Draupne Shale is monitored during three consecutive fluid exposure phases. This shale appears to be resilient to CO2 exposure as its integrity is neither compromised by notable Young’s modulus and Poisson’s ratio nor P- and S-wave velocity changes. No significant changes in Young’s modulus and Poisson’s ratio seismic dispersion are observed. This absence of notable changes in rock properties is attributed to Draupne being a calcite-poor shale resilient to acidic CO2-bearing brine that may be a suitable candidate for CCS.

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