The Role of Moment Tensors in the Characterization of Hydraulic Stimulations

Rodrı́guez, Ismael; Rutledge, James; Stanchits, Sergei

doi:10.1007/978-3-319-77359-9_8

Cited by 3 publications

(1 citation statement)

References 36 publications

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“…An alternative decomposition of the seismic moment tensor is the biaxial decomposition (Chapman and Leaney, 2012), whereby the source mechanism is interpreted in terms of a general disclocation source accompanied by a pressure change. The advantage of the biaxial decomposition is that it takes into account the effects of general anisotropy in the source region, and provides a more physically intuitive representation of a seismic source (e.g., Vera Rodriguez et al, 2018). Further, the biaxial decomposition provides fault planes and displacement vectors which may be used as input for the aforementioned stress inversion methods.…”

Section: Introductionmentioning

confidence: 99%

Inferring microseismic source mechanisms and in situ stresses during triaxial deformation of a North-Sea-analogue sandstone

et al. 2019

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Abstract. Monitoring microseismic activity provides a window through which to observe reservoir deformation during hydrocarbon and geothermal energy production, or CO2 injection and storage. Specifically, microseismic monitoring may help constrain geomechanical models through an improved understanding of the location and geometry of faults, and the stress conditions local to them. Such techniques can be assessed in the laboratory, where fault geometries and stress conditions are well constrained. We carried out a triaxial test on a sample of Red Wildmoor sandstone, an analogue to a weak North Sea reservoir sandstone. The sample was coupled with an array of piezo-transducers, to measure ultrasonic wave velocities and monitor acoustic emissions (AE) – sample-scale microseismic activity associated with micro-cracking. We calculated the rate of AE, localised the AE events, and inferred their moment tensor from P-wave first motion polarities and amplitudes. We applied a biaxial decomposition to the resulting moment tensors of the high signal-to-noise ratio events, to provide nodal planes, slip vectors, and displacement vectors for each event. These attributes were then used to infer local stress directions and their relative magnitudes. Both the AE fracture mechanisms and the inferred stress conditions correspond to the sample-scale fracturing and applied stresses. This workflow, which considers fracture models relevant to the subsurface, can be applied to large-scale geoengineering applications to obtain fracture mechanisms and in-situ stresses from recorded microseismic data.

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Section: Introductionmentioning

confidence: 99%

Inferring microseismic source mechanisms and in situ stresses during triaxial deformation of a North-Sea-analogue sandstone

et al. 2019

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A review of laboratory studies and theoretical analysis for the interaction mode between induced hydraulic fractures and pre-existing fractures

Zhang

Sun

2021

Journal of Natural Gas Science and Engineering

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Strain microseismics: Radiation patterns, synthetics, and moment tensor resolvability with distributed acoustic sensing in isotropic media

Rodrı́guez

Wuestefeld

2020

GEOPHYSICS

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We have derived analytical formulations for the strain field produced by a moment tensor source in homogeneous isotropic media. Such formulations are important for microseismic projects that increasingly are monitored with fiber-optic distributed acoustic sensing (DAS) systems. We find that the spatial derivative of displacement produces new terms in strain proportional to [Formula: see text] with [Formula: see text]. In viscoelastic media, the derivative also produces an additional far-field term that is scaled by a frequency-dependent factor. When comparing with full wavefield synthetic data, we observe that the new terms proportional to [Formula: see text] can be considered part of a near-field in strain, similar to the practice with the displacement formulation. Analyses of moment tensor resolvability show that full moment tensors are resolvable with P-wave information from two or more noncoplanar vertical DAS cable geometries if intermediate- and far-field terms are considered and that S-wave information alone cannot constrain full moment tensors using only vertical wells. These results mirror previous observations made with displacement measurements. Furthermore, the addition of the new terms proportional to [Formula: see text] in strain improves the moment tensor resolvability but only in the case of a single vertical array. In the case of a single deviated/horizontal well, we can, in theory, resolve a full moment tensor but a case-by-case analysis is necessary to identify regions of full constraint around the well and the necessary noise conditions to guarantee reliable solutions. Real DAS measurements also are affected by the gauge length and interrogator details. In the case of the gauge length, we observe that this operator does not change the resolvability of the problem but it does affect inversion stability. The results derived here represent theoretical limits or in some cases specific examples. Practical implementations require analyses of conditioning, noise, coupling, and the effect of gauge length on a case-by-case basis.

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The Role of Moment Tensors in the Characterization of Hydraulic Stimulations

Cited by 3 publications

References 36 publications

Inferring microseismic source mechanisms and in situ stresses during triaxial deformation of a North-Sea-analogue sandstone

Inferring microseismic source mechanisms and in situ stresses during triaxial deformation of a North-Sea-analogue sandstone

A review of laboratory studies and theoretical analysis for the interaction mode between induced hydraulic fractures and pre-existing fractures

Strain microseismics: Radiation patterns, synthetics, and moment tensor resolvability with distributed acoustic sensing in isotropic media

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