Data-Driven, In Situ, Relative Sensor Calibration Based on Waveform Fitting Moment Tensor Inversion

Rodriguez, Ismael Vera; Stanchits, Sergei; Burghardt, Jeffrey

doi:10.1007/s00603-016-1144-4

Cited by 25 publications

(15 citation statements)

References 31 publications

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“…Shear seismic events are often dominant in actual production fields (Maxwell & Cipolla 2011;Šílený et al 2014;Staněk & Eisner 2017) and in situ experiments (Ishida et al 2019). Previous studies of hydraulic fracturing in the laboratory also showed that significant proportions of induced seismic events were shear-type for rocks such as shale (Bennour et al 2015;Zhang et al 2019), sandstone (Stoeckhert et al 2015;Rodriguez et al 2017), slate (Stoeckhert et al 2015) and granite (Ishida et al 2016;Yamamoto et al 2019), even for experiments adopting loading conditions and sample sizes similar to those used in the present study (Yamamoto et al 2019). Although moment tensor analysis for laboratory-observed AE events is difficult because of the complicated characteristics of AE sensors, such studies also reported that a significant proportion of AE events were shear-type (Rodriguez et al 2017;Yamamoto et al 2019).…”

Section: Interpretation Of Dominant Focal Mechanismsmentioning

confidence: 99%

Tensile-dominant fractures observed in hydraulic fracturing laboratory experiment using eagle ford shale

Naoi

Chen

Yamamoto

et al. 2020

Geophysical Journal International

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SUMMARY Hydraulic fracturing plays a vital role in the development of unconventional energy resources, such as shale gas/oil and enhanced geothermal systems to increase the permeability of tight rocks. In this study, we conducted hydraulic fracturing experiments in a laboratory using carbonate-rich outcrop samples of Eagle Ford shale from the United States. We used a thermosetting acrylic resin containing a fluorescent compound as a fracturing fluid. Immediately after fracturing, the liquid resin penetrated in the fractured blocks was hardened by applying heat. Then, the crack was viewed under UV irradiation, where the fluorescent resin allowed the induced fracture to be clearly observed, indicating the formation of simple, thin bi-wing planar fractures. We observed the detailed structure of the fractures from microscopy of thin cross-sections, and found that their complexity and width varied with the distance from the wellbore. This likely reflects the change in the stress state around the tip of the growing fracture. The interaction between fractures and constituent grains/other inclusions (e.g. organic substances) seemed to increase the complexity of the fractures, which may contribute to the efficient production of shale gas/oil via hydraulic fracturing. We first detected acoustic emission (AE) signals several seconds before the peak fluid pressure was observed, and the active region gradually migrated along the microscopically observed fracture with increasing magnitude. Immediately after the peak pressure was observed, the fluid pressure dropped suddenly (breakdown) with large seismic waves that were probably radiated by dynamic propagation of the fracture; thereafter, the AE activity stopped. We applied moment tensor inversion for the obtained AE events by carefully correcting the AE sensor characteristics. Almost all of the solutions corresponded to tensile events that had a crack plane along the maximum compression axis, as would be expected based on the conventional theory of hydraulic fracturing. Such domination of tensile events has not been reported in previous studies based on laboratory/in situ experiments, where shear events were often dominant. The extreme domination of the tensile events in the present study is possibly a result of the use of rock samples without any significant pre-existing cracks. Our experiments revealed the fracturing behaviour and accompanying seismic activities of very tight rocks in detail, which will be helpful to our understanding of fracturing behaviour in shale gas/oil resource production.

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Section: Interpretation Of Dominant Focal Mechanismsmentioning

confidence: 99%

Tensile-dominant fractures observed in hydraulic fracturing laboratory experiment using eagle ford shale

Naoi

Chen

Yamamoto

et al. 2020

Geophysical Journal International

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“…Uncertainties in wave propagation velocities can take four forms: measuring procedure, homogeneous assumption, time‐invariance assumption, and dispersion. For the shear wave velocities, uncertainty can also be expected from their interpretation via processing rather than direct measurements (see Vera Rodriguez et al, , for details on the derivation of shear wave velocity in this data set). Uncertainties from the measuring procedure are neglected in our analysis because their magnitude is small compared to the other three sources of error.…”

Section: Modeling Of Different Sources Of Uncertainty On the Estimatementioning

confidence: 89%

“…Model heterogeneity can be glimpsed from the variation in compressional velocities measured with ultrasonic pulses along different travel paths between transducers (see Vera Rodriguez et al, , for details of the compressional velocities measured in this experiment). From the magnitude of this variation, we estimate that the uncertainty introduced by neglecting the velocity heterogeneity of the block lies on the order of 6%.…”

Section: Modeling Of Different Sources Of Uncertainty On the Estimatementioning

confidence: 89%

“…From this experiment, it was determined that compressional waves produced a negative first motion. The same data set is used in Vera Rodriguez et al (), where the calibration of the measurements is described in detail.…”

Section: Description Of the Experimentsmentioning

confidence: 99%

“…Stanchits et al () report AE location errors on the order of 6 mm for similar hydraulic fracturing experiments on shale and sandstone blocks. Vera Rodriguez et al (, ) demonstrate improvements in location accuracy with the incorporation of shear wave information using the coalescence microseismic mapping algorithm (Drew et al, ). Location uncertainties from coalescence mapping are reported in the form of regions with higher probability.…”

Section: Modeling Of Different Sources Of Uncertainty On the Estimatementioning

confidence: 99%

See 2 more Smart Citations

Spatial and Temporal Variation of Seismic Attenuation During Hydraulic Fracturing of a Sandstone Block Subjected to Triaxial Stress

Rodrı́guez

Stanchits

2017

JGR Solid Earth

Self Cite

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Q factors estimated with spectral ratios describe the attenuation experienced by seismic arrivals in their travel from the source(s) to the receiver(s). When Q is not the same along the travel path of each arrival, the formulation must incorporate two Q factors making the problem indeterminate. Here we show that by assuming that Q is a random variable, the parameters of its probability distribution can be recovered through a mapping workflow using the spectral ratios. An advantage of such a workflow is that uncertainties in source location and velocity model can also be incorporated by representing these elements as random variables. We apply such a methodology to an acoustic emission (AE) data set from a laboratory experiment of hydraulic fracturing in a Colton sandstone block. We assume that the probability distribution of Q is normal. Anisotropic mean (μQ) values correlate with the triaxial stress conditions imposed at the boundaries of the block, with higher stress corresponding with less attenuation. The μQ values estimated within time intervals in the direction perpendicular to the hydraulic fracture plane correlate with stress buildup at the borehole during fracture propagation and borehole pressure relaxation or drop during fracture closure. The standard deviations (σQ) reflect the attenuation heterogeneity within the sampled regions. An increase in heterogeneity is correlated with pressure buildup at the borehole, which we interpret to reflect a dynamic stress gradient formed from the hydraulic fracture toward the surroundings.

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Laboratory Acoustic Emission in Study of Rock Mechanics

Manthei

Zang

Große

2021

Springer Tracts in Civil Engineering

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Data-Driven, In Situ, Relative Sensor Calibration Based on Waveform Fitting Moment Tensor Inversion

Cited by 25 publications

References 31 publications

Tensile-dominant fractures observed in hydraulic fracturing laboratory experiment using eagle ford shale

Tensile-dominant fractures observed in hydraulic fracturing laboratory experiment using eagle ford shale

Spatial and Temporal Variation of Seismic Attenuation During Hydraulic Fracturing of a Sandstone Block Subjected to Triaxial Stress

Laboratory Acoustic Emission in Study of Rock Mechanics

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