Direct laboratory observation of patchy saturation and its effects on ultrasonic velocities

Lebedev, Maxim; Toms-Stewart, Julianna; Clennell, Ben; Pervukhina, Marina; Shulakova, Valeriya; Paterson, Lincoln; Müller, Tobias M.; Gurevich, Boris; Wenzlau, Fabian

doi:10.1190/1.3064142

Cited by 89 publications

(63 citation statements)

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“…This rapid drop if velocities is caused by the transition of scCO 2 from the patchy distribution at which pore pressure has no time to equilibrate within the liquid phase to a more homogeneous distribution at which differences in wave-induced pore pressure have time to flow and equilibrate among the various phases. These patchy and effectively homogeneous states can be described with the Gassmann-Hill and Gassmann-Wood theoretical models, respectively (e.g., Müller et al, 2008;Lebedev et al, 2009;Ling et al, 2009;Müller et al, 2010;Caspari et al, 2011 Comparison of P-and S-wave log velocities with laboratory-measured velocities on brine-saturated samples at reservoir conditions and the ones calculated using Gassman fluid substitution model from laboratory measurements on the dry samples. The result of Gassmann's fluid substitution using the laboratory measurements on dry sample 1442.1H cut parallel to the bedding is shown in the insert.…”

Section: Effects Of Co 2 Injection Into Dry Rockmentioning

confidence: 99%

An experimental study of acoustic responses on the injection of supercritical CO2 into sandstones from the Otway Basin

et al. 2013

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Quantitative knowledge of the acoustic response of rock from an injection site on supercritical CO 2 (scCO 2 ) saturation is crucial for understanding the feasibility of time-lapse seismic monitoring of CO 2 plume migration. A suite of shaley sandstones from the injection interval of the CRC-2 well, Otway Basin, Australia is tested to reveal the effects of supercritical CO 2 injection on acoustic responses. CO 2 is first injected into dry samples, flushed out with brine and then injected again into brine-saturated samples. Such a suite of experiments allows us to obtain acoustic velocities of the samples for a wide range of CO 2 /brine saturations from 0% to 100%. On injection of scCO 2 into brine-saturated samples, the rocks exhibit a decrease of compressional velocities by about 7% with the increase of CO 2 saturation from 0% to a maximum of about 50%. Anisotropy of the shaley sandstones from the Otway Basin must be taken into account as the difference in the velocities normal and parallel to bedding is comparable with the perturbation due to CO 2 injection and the samples of different orientations exhibit transition from Gassmann-Hill to Gassmann-Wood bound at different scCO 2 saturations. Changes of the dry samples before and after the CO 2 injection (if any) are not traceable by acoustic methods.

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Section: Effects Of Co 2 Injection Into Dry Rockmentioning

confidence: 99%

An experimental study of acoustic responses on the injection of supercritical CO2 into sandstones from the Otway Basin

et al. 2013

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“…Because of recent work indicating inhomogeneous CO 2 distribution during small scale (core and field) injections (Benson et al, 2005, Daley et al, 2008, Lebedev, et al, 2009, Benson, 2008 we have chosen a patchy saturation fluid substitution theory. This theoretical model, initially proposed by White (1975), includes the corrections made by Dutta and Seriff (1979), for the prediction and interpretation of seismic property changes due to partial CO 2 saturation.…”

Section: Petrophysical Model -Patchy Saturationmentioning

confidence: 99%

Constraining the reservoir model of an injected CO2 plume with crosswell CASSM at the Frio-II brine pilot

Daley

Ajo‐Franklin

Doughty

2011

International Journal of Greenhouse Gas Control

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Crosswell CASSM (continuous active-source seismic monitoring) data was acquired as part of the Frio-II brine pilot CO 2 injection experiment. To gain insight into the CO 2 plume evolution, we have integrated the 3D multiphase flow modeling code TOUGH2 with seismic simulation codes via a petrophysical model that predicts seismic velocity for a given CO 2 saturation. Results of forward seismic modeling based on the CO 2 saturation distribution produced by an initial TOUGH2 model compare poorly with the CASSM data, indicating that the initial flow model did not capture the actual CO 2 plume dynamics. Updates to the TOUGH2 model required to better match the CASSM field data indicate vertical flow near the injection well, with increased horizontal plume growth occurring at the top of the reservoir sand. The CASSM continuous delay time data are ideal for constraining the modeled spatiotemporal evolution of the CO 2 plume and allow improvement in reservoir model and estimation of CO 2 plume properties.

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“…Laboratory observations have also demonstrated the effect of partial saturation on acoustic velocities ͑e.g., Winkler and Nur, 1979;Murphy, 1982;Paffenholz and Burkhardt, 1989;Knight et al, 1998͒ and are supported by X-ray computer tomography images of the patch distribution ͑e.g., Cadoret et al, 1995;Monsen and Johnstad, 2005;Lebedev et al, 2009;Toms-Stewart et al, 2009͒ and numerical simulations ͑e.g., Carcione et al, 2003;Masson and Pride, 2007;Picotti et al, 2007;Wenzlau and Müller, 2009͒. Wave-induced fluid flow effects in the fluid are modeled by isolated spherical gas patches in the liquid saturating a homogeneous matrix, as first proposed by White ͑1975͒. Since then, significant progress has been made by considering various patch distributions and flow regimes Odé, 1979a, 1979b;Norris, 1993;Gelinsky et al, 1998;Johnson, 2001;Gurevich, 2004, 2005;Müller et al, 2008;Gurevich et al, 2009;Picotti et al, 2010͒.…”

Section: Introductionmentioning

confidence: 99%

Exact expression for the effective acoustics of patchy-saturated rocks

2010

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Seismic effects of a partially gas-saturated subsurface have been known for many years. For example, patches of nonuniform saturation occur at the gas-oil and gas-water contacts in hydrocarbon reservoirs. Open-pore boundary conditions are applied to the quasi-static Biot equations of poroelasticity to derive an exact analytic expression of the effective bulk modulus for partially saturated media with spherical gas patches larger than the typical pore size. The pore fluid and the rock properties can have different values in the central sphere and in the surrounding region. An analytic solution prevents loss of accuracy from ill-conditioned equations as encountered in the numerical solution for certain input. For a sandstone saturated with gas and water, we found that the P-wave velocity and attenuation in conventional models differ as much as 15% from the exact solution at seismic frequencies. This makes the use of present exact theory necessary to describe patchy saturation, although ͑more realistic͒ complex patch shapes and distributions were not considered. We found that, despite earlier corrections, the White conventional model does not yield the correct low-frequency asymptote for the attenuation.

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Direct laboratory observation of patchy saturation and its effects on ultrasonic velocities

Cited by 89 publications

References 0 publications

An experimental study of acoustic responses on the injection of supercritical CO2 into sandstones from the Otway Basin

An experimental study of acoustic responses on the injection of supercritical CO2 into sandstones from the Otway Basin

Constraining the reservoir model of an injected CO2 plume with crosswell CASSM at the Frio-II brine pilot

Exact expression for the effective acoustics of patchy-saturated rocks

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