Influence of the Creep Effect on the Low-Frequency Measurements of the Elastic Moduli of Sedimentary Rocks

Chavez, R.; Mikhaltsevitch, Vassili; Lebedev, Maxim; Gurevich, Boris; Vargas, Edson; Vásquez, Guilherme

doi:10.3997/2214-4609.201901033

Cited by 3 publications

(4 citation statements)

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“…Continuous FO and PT measurement over time could also be extended to conventional creep measurements in the absence of CO 2 . Chavez et al [97] later studied FO-measured creep effects on a limestone, a sandstone, and a shale at 2 Hz but at room-dry and uniaxial conditions. Instead of 575 h, they measured for 120 h. It appears as though they did not consider anisotropy because they did not specify the orientation of their Eagle Ford Shale and only included isotropic calculations.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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“…FO is applied to measure properties of all sedimentary rock types: sandstones [21,33,43,79,89,90,, carbonates [21,33,64,79,92,99,100,119,120,[136][137][138][139][140][141][142][143][144][145][146][147][148][149], and shales [75,100,119,[150][151][152][153][154][155][156][157][158][159][160]. FO is also applied to igneous rocks [21,70,71,73,[161][162][163]…”

Section: Forced-oscillation (Fo)mentioning

confidence: 99%

“…Wellington is also studied by Mikhaltsevitch et al [160] but at different saturation states with similar dispersion features (and explanation) as Mancos [180]: peak Q −1 EV and Q −1 EH at 2 and 6 Hz. Mikhaltsevitch et al [160] also includes the Eagle Ford experiments by Chavez et al [119]. Rørheim [4] observed non-simultaneous uniaxial-stress E V and uniaxial-strain C 33 behaviours as well as decreasing Q −1 EV and Q −1 C33 with decreasing saturation for five differently oriented and saturated Pierre specimens.…”

Section: Shalesmentioning

confidence: 99%

“…Lozovyi [159] succeeded Szewczyk [185] by comparing the static and dynamic stiffness of Opalinus Clay and three other anonymous specimens [186][187][188]. Chavez et al [119] conducted FO creep tests on three dry sedimentary rocks at constant 2 Hz for 120 hours. Creep effects significantly impacted the moduli for all three specimens but the shale was most affected.…”

Section: Shalesmentioning

confidence: 99%

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On Frequency-Dependent Rock Experiments: A Comparative Review

Rørheim¹

2022

Preprint

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Rock properties are environment-and condition-dependent which render field-laboratory comparisons ambiguous for a number of known and unknown reasons that constitute the upscaling problem. Unknowns are first transformed into knowns in a controlled environment (laboratory) and second in a volatile environment (field). Causality-bound dispersion and attenuation are respectively defined as rock properties that are frequency-and distance-dependent: dispersion implies non-zero attenuation and vice versa. Forced-Oscillation (FO), Resonant Bar (RB), and Pulse-Transmission (PT) are the customary techniques to measure rock properties at Hz, kHz, and MHz frequencies. Notably FO has emerged as the current champion in bridging the fieldlaboratory void in recent years. Not only is FO probing seismic (Hz) frequencies but with ∼ 10 −6 strain amplitudes it is also similar to field seismic. RB and PT are concisely however FO is verbosely elaborated by chronologically compiling most (if not all) FO studies on sedimentary rocks and comparing all available FO measurements on reference materials such as lucite, aluminium, and PEEK. First of its kind, this inter-laboratory comparison may serve as a reference for others who seek to verify their own results. Differences between FO are discussed with alternative strain and stress sensors being the focal points. Other techniques such as Resonant Ultrasound Spectroscopy (RUS), Laser UltraSonics (LUS), and Differential Acoustic Resonance Spectroscopy (DARS) that are similar to FO, RB, and PT are also described. Only time will tell what the future holds for FO but plausible improvements for the future are ultimately given which may elevate it even further.

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On the low-frequency elastic response of Pierre Shale during temperature cycles

Rørheim

Bauer

Holt

2021

Geophysical Journal International

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Summary The impact of temperature on elastic rock properties is less-studied and thus less-understood than that of pressure and stress. Thermal effects on dispersion are experimentally observed herein from seismic to ultrasonic frequencies: Young’s moduli and Poisson’s ratios plus P- and S-wave velocities are determined by forced-oscillation (FO) from 1 to 144 Hz and by pulse-transmission (PT) at 500 kHz. Despite being the dominant sedimentary rock type, shales receive less experimental attention than sandstones and carbonates. To our knowledge, no other FO studies on shale at above ambient temperatures exist. Temperature fluctuations are enforced by two temperature cycles from 20 via 40 to 60○C and vice versa. Measured rock properties are initially irreversible but become reversible with increasing number of heating and cooling segments. Rock property-sensitivity to temperature is likewise reduced. It is revealed that dispersion shifts towards higher frequencies with increasing temperature (reversible if decreased), Young’s moduli and P-wave velocity moduli and P-wave velocity maxima occur at 40○C for frequencies below 56 Hz, and S-wave velocities remain unchanged with temperature (if the first heating segment is neglected) at seismic frequencies. In comparison, ultrasonic P- and S-wave velocities are found to decrease with increasing temperatures. Behavioural differences between seismic and ultrasonic properties are attributed to decreasing fluid viscosity with temperature. We hypothesize that our ultrasonic recordings coincide with the transition-phase separating the low- and high-frequency regimes while our seismic recordings are within the low-frequency regime.

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Influence of the Creep Effect on the Low-Frequency Measurements of the Elastic Moduli of Sedimentary Rocks

Cited by 3 publications

References 0 publications

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

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

On Frequency-Dependent Rock Experiments: A Comparative Review

On the low-frequency elastic response of Pierre Shale during temperature cycles

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