Reservoir fracture characterization from seismic scattered waves

Fang, Xinding; Fehler, Michael; Zhu, Zhenya; Zheng, Yingcai; Burns, Daniel R.

doi:10.1093/gji/ggt381

Cited by 29 publications

(13 citation statements)

References 35 publications

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“…In numerical simulations, we use a 3D FD modeling program to simulate elastic seismic wave propagation for EMM and DFM (Fang et al, 2014). The accuracy of our numerical simulation program has been validated through comparison with the boundary element method (Chen et al, 2012).…”

Section: Numerical Modeling Of Seismic Wave Scattering By Random Fracmentioning

confidence: 99%

“…The accuracy of our numerical simulation program has been validated through comparison with the boundary element method (Chen et al, 2012). The same program was also used in the study of fracture characterization from seismic scattered waves (Fang et al, 2013b(Fang et al, , 2014Zheng et al, 2013). We will first present the 3D simulation results and then investigate in more detail the influence of different fracture spatial distributions on the AVO analysis through 2D Monte Carlo simulations.…”

Section: Numerical Modeling Of Seismic Wave Scattering By Random Fracmentioning

confidence: 99%

“…Effective mediumbased approaches use specularly reflected waves (P-to-P or Pto-S) for fracture characterization (Shaw and Sen, 2004). However, individual fractures can scatter seismic energy and produce scattered waves even when fracture spacing is comparable with the seismic wavelength (Willis et al, 2006;Fang et al, 2014). Willis et al (2006), Fang et al (2013bFang et al ( , 2014, and Zheng et al (2013) develop different scattering/diffraction-based methods to extract fracture information by analyzing the characteristics of multiple scattered waves by fractures.…”

Section: Introductionmentioning

confidence: 99%

“…However, individual fractures can scatter seismic energy and produce scattered waves even when fracture spacing is comparable with the seismic wavelength (Willis et al, 2006;Fang et al, 2014). Willis et al (2006), Fang et al (2013bFang et al ( , 2014, and Zheng et al (2013) develop different scattering/diffraction-based methods to extract fracture information by analyzing the characteristics of multiple scattered waves by fractures. The scattering-based methods are more general than AVOAz approaches, and their results can be approximated by the effective medium approaches under a lowfrequency assumption.…”

Section: Introductionmentioning

confidence: 99%

“…The scattering-based methods are more general than AVOAz approaches, and their results can be approximated by the effective medium approaches under a lowfrequency assumption. However, laboratory experiments (Fang et al, 2014;Zhu et al, 2015) show that specular reflections and fracture diffractions from a fractured layer can have a similar magnitude and they may interfere with each other in seismic analysis. This leads to the speculation that scattering from individual fractures may affect AVOAz analysis when fractures are not uniformly distributed, and this calls into question the validity of the effective medium assumption.…”

Section: Introductionmentioning

confidence: 99%

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Fracture clustering effect on amplitude variation with offset and azimuth analyses

2017

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Traditional amplitude variation with offset and azimuth (AVOAz) analysis for fracture characterization extracts fracture properties through analysis of reflection AVOAz to determine anisotropic parameters (e.g., Thomsen's parameters) that are then related to fracture properties. The validity of this method relies on the basic assumption that a fractured unit can be viewed as an equivalent anisotropic medium. As a rule of thumb, this assumption is taken to be valid when the fracture spacing is less than λ∕10. Under the effective medium assumption, diffractions from individual fractures destructively interfere and only specular reflections from boundaries of a fractured layer can be observed in seismic data. The effective medium theory has been widely used in fracture characterization, and its applicability has been validated through many field applications. However, through numerical simulations, we find that diffractions from fracture clusters can significantly distort the AVOAz signatures when a fracture system has irregular spacing even though the average fracture spacing is much smaller than a wavelength (e.g., ≪ λ∕10). Contamination by diffractions from irregularly spaced fractures on reflections can substantially bias the fracture properties estimated from AVOAz analysis and may possibly lead to incorrect estimates of fracture properties. Additionally, through Monte Carlo simulations, we find that fracture spacing uncertainty inverted from amplitude variation with offset (AVO) analysis can be up to 10%-20% when fractures are not uniformly distributed, which should be the realistic state of fractures present in the earth. Also, AVOAz and AVO analysis gives more reliable estimates of fracture properties when reflections at the top of the fractured layer are used compared with those from the bottom of the layer.

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Section: Numerical Modeling Of Seismic Wave Scattering By Random Fracmentioning

confidence: 99%

Section: Numerical Modeling Of Seismic Wave Scattering By Random Fracmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fracture clustering effect on amplitude variation with offset and azimuth analyses

2017

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Hollow Silica Spheres Embedded in a Porous Carbon Matrix and Its Superior Performance as the Anode for Lithium‐Ion Batteries

Cao

Chuan

et al. 2015

Part & Part Syst Charact

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Silica (SiO2) is regarded as one of the most promising anode materials for lithium‐ion batteries due to the high theoretical specific capacity and extremely low cost. However, the low intrinsic electrical conductivity and the big volume change during charge/discharge cycles result in a poor electrochemical performance. Here, hollow silica spheres embedded in porous carbon (HSS–C) composites are synthesized and investigated as an anode material for lithium‐ion batteries. The HSS–C composites demonstrate a high specific capacity of about 910 mA h g−1 at a rate of 200 mA g−1 after 150 cycles and exhibit good rate capability. The porous carbon with a large surface area and void space filled both inside and outside of the hollow silica spheres acts as an excellent conductive layer to enhance the overall conductivity of the electrode, shortens the diffusion path length for the transport of lithium ions, and also buffers the volume change accompanied with lithium‐ion insertion/extraction processes.

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Simplified Seismic Modelling of Fractured Rock: How Effective is the Localised Effective Medium Compared to Explicit Representation of Individual Fractures

2021

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Seismic waves can be an effective probe to retrieve fracture properties particularly when measurements are coupled with forward and inverse modelling. These seismic models then need an appropriate representation of the fracturing. The fractures can be modelled either explicitly, considering zero thickness frictional slip surfaces, or by considering an effective medium which incorporates the effect of the fractures into the properties of the medium, creating anisotropy in the wave velocities. In this work, we use a third approach which is a hybrid of the previous two. The area surrounding the predefined fracture is treated as an effective medium and the rest of the medium is made homogeneous and isotropic, creating a Localised Effective Medium (LEM). LEM can be as accurate as the explicit but more efficient in run-time. We have shown that the LEM model can closely match an explicit model in reproducing waveforms recorded in a laboratory experiment, for wave propagating parallel and perpendicular to the fractures. The LEM model performs close to the explicit model when the wavelength is much larger than the element size and larger than the fracture spacing. By the definition of the LEM model, we expect that as the LEM layer becomes coarser the model will start approaching the effective medium result. However, what are the limitations of the LEM and is there a balance between the stiffness, the frequency and the thickness, where the LEM performs close to an explicit model or approaches the effective medium model? To define the limits of the LEM we experiment varying fracture stiffness and source frequency. We then compare for each frequency and stiffness the explicit and effective medium with five models of LEM with different thickness. Finally, we conclude that the thick LEM layers with lower resolution perform the same as the thinner and finer resolution LEM layers for lower frequencies and higher fracture stiffness.

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Reservoir fracture characterization from seismic scattered waves

Cited by 29 publications

References 35 publications

Fracture clustering effect on amplitude variation with offset and azimuth analyses

Fracture clustering effect on amplitude variation with offset and azimuth analyses

Hollow Silica Spheres Embedded in a Porous Carbon Matrix and Its Superior Performance as the Anode for Lithium‐Ion Batteries

Simplified Seismic Modelling of Fractured Rock: How Effective is the Localised Effective Medium Compared to Explicit Representation of Individual Fractures

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