Seismic inversion of shale reservoir properties using microseismic-induced guided waves recorded by distributed acoustic sensing (DAS)

Geophysics ◽  
2021 ◽  
pp. 1-58
Author(s):  
Bin Luo ◽  
Ariel Lellouch ◽  
Ge Jin ◽  
Biondo Biondi ◽  
James Simmons
Keyword(s):  
Hydraulic Fracturing ◽  
Guided Waves ◽  
Wave Dispersion ◽  
Seismic Inversion ◽  
Dispersion Relations ◽  
Guided Wave ◽  
Low Velocity ◽  
Propagator Matrix ◽  
Shale Formation ◽  
Shale Reservoir

Shale formation properties are crucial for the hydrocarbon production performance of unconventional reservoirs. Microseismic-induced guided waves, which propagate within the low-velocity shale formation, are an ideal candidate for accurate estimation of the shale thickness, velocity, and anisotropy. A DAS fiber deployed along the horizontal section of a monitor well can provide a high-resolution recording of guided waves excited by microseismic events during hydraulic fracturing operations. These guided waves manifest a highly dispersive behavior that allows for seismic inversion of the shale formation properties. An adaptation of the propagator matrix method is presented to estimate guided wave dispersion curves and its accuracy is validated by comparison to 3-D elastic wavefield simulations. The propagator matrix formulation holds for cases of vertical transverse isotropy (VTI) as well. A sensitivity analysis of the theoretical dispersion relations of the guided waves shows that they are mostly influenced by the thickness and S-wave velocity of the low-velocity shale reservoir. The VTI parameters of the formation are also shown to have an impact on the dispersion relations. These physical insights provide the foundation for a dispersion-based model inversion for a 1-D depth-dependent structure of the reservoir and its surroundings. The inversion procedure is validated in a synthetic case and applied to the field records collected in an Eagle Ford hydraulic fracturing project. The inverted structure agrees well with a sonic log acquired several hundred meters away from the monitor well. Seismic inversion using guided wave dispersion therefore shows promise to become a novel and cost-effective strategy for in-situ estimation of reservoir structure and properties, which complements microseismic-based interpretation and production-related information.

DAS observations and modeling of perforation-induced guided waves in a shale reservoir

2019 ◽  
Vol 38 (11) ◽  
pp. 858-864 ◽  
Author(s):  
Ariel Lellouch ◽  
Steve Horne ◽  
Mark A. Meadows ◽  
Stuart Farris ◽  
Tamas Nemeth ◽  
...  
Keyword(s):  
Guided Waves ◽  
Low Velocity ◽  
S Waves ◽  
Velocity Models ◽  
Shale Formation ◽  
Shale Reservoir ◽  
Distributed Acoustic Sensing ◽  
Induced Changes ◽  
Synthetic Modeling ◽  
High Frequency Content

Perforation shots can be recorded by downhole distributed acoustic sensing (DAS) arrays. In this study, we demonstrate that guided waves induced by perforation shots propagate in a low-velocity shale reservoir layer. Such guided waves have a high frequency content of up to 700 Hz and are dispersive, with lower frequencies propagating faster than higher frequencies. They can propagate as P- and S-waves, and their group velocity is higher than their phase velocity. The high temporal and spatial resolution of the DAS array enables unaliased recording despite short wavelengths. The guided waves disappear from the records when the well exits the shale formation. Synthetic modeling predicts their existence for acoustic and elastic cases in simple velocity models. We show that perforation shots from an offset well at a distance of about 270 m can be recorded by the DAS array. Induced guided S-waves undergo significant disturbances while propagating through previously stimulated zones. These disturbances manifest as kinematic and dynamic changes of the recorded wavefield and as scattered events. The nature of the stimulation-induced changes is interpreted as a combination of unknown spatial and temporal effects linked to fluid-filled fractures. Guided waves hold tremendous potential for high-resolution reservoir imaging and should be used in conjunction with conventional DAS arrays and state-of-the-art DAS interrogators.

scholarly journals Assessment of low-velocity impact damage in composites by the measure of second-harmonic guided waves with the phase-reversal approach

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988107 ◽  
Author(s):  
Weibin Li ◽  
Chang Jiang ◽  
Xinlin Qing ◽  
Liangbing Liu ◽  
Mingxi Deng
Keyword(s):  
Guided Waves ◽  
Second Harmonic ◽  
Impact Damage ◽  
Guided Wave ◽  
Second Order ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Phase Reversal ◽  
The Impact

Structural strength and integrity of composites can be considerably affected by the low-velocity impact damage due to the unique characteristics of composites, such as layering bonded by adhesive and the weakness to impact. For such damage, there is an urgent need to develop advanced nondestructive testing approaches. Despite the fact that the second harmonics could provide information sensitive to the structural health condition, the diminutive amplitude of the measured second-order harmonic guided wave still limits the applications of the second-harmonic generation–based nonlinear guided wave approach. Herein, laminated composites suffered from low-velocity impact are characterized by use of nonlinear guided waves. An enhancement in the signal-to-noise ratio for the measure of second harmonics is achieved by a phase-reversal method. Results obtained indicate a monotonic correlation between the impact-induced damage in composites and the relative acoustic nonlinear indicator of guided waves. The experimental finding in this study shows that the measure of second-order harmonic guided waves with a phase-reversal method can be a promising indicator to impact damage rendering in an improved and reliable manner.

Estimation of fracture height using microseismicity associated with hydraulic fracturing

Geophysics ◽  
1998 ◽  
Vol 63 (3) ◽  
pp. 908-917
Author(s):  
Yafei Wu ◽  
George A. McMechan
Keyword(s):  
Hydraulic Fracturing ◽  
Fracture Zone ◽  
Pure Shear ◽  
Guided Wave ◽  
Low Velocity ◽  
Fractured Zone ◽  
Source Type ◽  
Aftershock Sequences ◽  
Fracture Height ◽  
Shear Failures

The ratio of horizontal‐to‐vertical (H/V) particle velocity in background microseismic radiation associated with hydraulic fracturing is substantially higher in the dilatant, low‐velocity fractured zone than it is outside. This provides a useful diagnostic for determining the height of the fractured zone. Numerical synthesis of guided wave phenomena within the low‐velocity fractured zone accounts for much of the observed behavior, but measured H/V patterns are not totally consistent with either pure tensile or pure shear sources. A composite model containing both tensile‐compressional sources and asperity shear failures appears to satisfy the main observations better than either source type does alone. This composite is consistent with current models of earthquake aftershock sequences, which also have different mechanisms at the edges and in the interior of a fracture zone (tensile and shear, respectively). The H/V phenomenon is consistent with a predominance of energy with shear‐wave polarization traveling at postcritical angles, produced either directly by the source or by P-to-S conversion at the edges of the fracture zone. The H/V ratios are enhanced by increasing dilatancy, which decreases the velocity within the fracture zone.

Temperature Effects on Guided Wave Structural Damage Detection

2008 ◽  
Vol 47-50 ◽  
pp. 129-132 ◽  
Author(s):  
Chan Yik Park ◽  
Seung Moon Jun
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Guided Waves ◽  
Guided Wave ◽  
Low Velocity Impact ◽  
Structural Damage Detection ◽  
Low Velocity ◽  
Simple Method ◽  
Temperature Changes ◽  
Health Monitoring Systems

Guided wave structural damage detection is one of promising candidates for the future aircraft structural health monitoring systems. There are several advantages of guided wave based damage detection: well established theoretical studies, simple sensor devices, large sensing areas, good sensitivity, etc. However, guided wave approaches are still vulnerable to false warnings of detecting damage due to temperature changes of the structures. Therefore, one of main challenges is to find an effective way of compensating temperature changes and to imply it to existing damage detect algorithms. In this paper, a simple method for applying guided waves to the problem of detecting damage in the presence of temperature changes is presented. In order to examine the effectiveness of the presented method, delaminations due to low-velocity impact on composite plate specimens are detected. The results show that the presented approach is simple but useful for detecting structural damage under the temperature variations.

A Simplified Dispersion Compensation Algorithm for the Interpretation of Guided Wave Signals

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Wenjun Wu ◽  
Yuemin Wang
Keyword(s):  
Guided Waves ◽  
Matching Pursuit ◽  
Dispersion Compensation ◽  
Wave Dispersion ◽  
Guided Wave ◽  
Center Frequency ◽  
Practical Applications ◽  
Compensation Algorithm ◽  
Nonlinear Phase ◽  
Mode Separation

Due to the multimodal and dispersive characteristics of guided waves, guided wave testing signals are always overlapped and difficult to separate for correct interpretations. To this end, a simplified dispersion compensation algorithm is put forward in this paper. The dispersion elimination is accomplished by compensating the second-order nonlinear phase shift of guided wave signals, which is the cause of the dispersion when narrow band exciting signals are used. This algorithm is easy to implement and has no need of prior knowledge of the guided wave dispersion relationship. Considering that the center frequency, which is a key parameter for this algorithm, is nearly impossible to determine accurately in practical applications, the effect of the center frequency deviation on the algorithm is further studied. Both theoretical analysis and numerical simulation indicate the insensitivity of the algorithm to the deviation of the center frequency, and hence, there is no need to determine the center frequency accurately, facilitating the practical use of the algorithm. Based on this simplified dispersion compensation algorithm and in cooperation with the matching pursuit method, the mode separation is further performed for interpreting of overlapped guided wave signals. Dispersion compensation is first applied to the testing signal with respect to a certain mode which will compress the waveform of the mode while the others still spread. Then, this compressed waveform is separated with the Gabor based matching pursuit method. Both simulation and experiment are designed to demonstrate the effectiveness of the proposed methods.

Transmission and detection of guided seismic waves in attenuating media

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1190-1199 ◽  
Author(s):  
Jorge O. Parra ◽  
Brian J. Zook ◽  
Pei‐Cheng Xu ◽  
Raymon L. Brown
Keyword(s):  
Seismic Waves ◽  
Guided Waves ◽  
Test Site ◽  
Guided Wave ◽  
Leaky Mode ◽  
Head Wave ◽  
British Petroleum ◽  
Low Velocity ◽  
Time Frequency ◽  
Shaly Sandstone

We can use guided seismic waves to map properties of reservoirs between wells, with the low‐velocity layers acting as waveguides. When guided waves are detected, they are an indication of the continuity of the bed examined. Guided waveforms are characterized by time‐frequency representations to study important physical properties of the beds acting as waveguides. We used full waveform seismic modeling in viscoelastic media to examine the required velocity contrasts and distances over which guided‐wave signals can be used. In one set of models, sandstones are the central waveguide lithology; in another set, shales. We applied these models, referred to here collectively as shaly sandstone waveguides, to a range of geological circumstances where either the sands or the shales represent the low‐velocity layers within a reservoir. To study the distances over which guided waves can be detected, we compared the amplitudes of the signals computed for the models, using a realistic source strength, to the signal levels determined from published borehole noise studies. In shaly sandstone waveguides, we find it is feasible to use particle velocity measurements to record guided waves above seismic noise levels in the frequency range of 60 to 800 Hz at well separations exceeding a distance of 800 m. However, pressure detectors such as hydrophones may only be useful up to distances of 400 m between wells. In addition to the issues of shaly sandstone waveguides and practical distances between wells, we present an application of guided waves using crosswell seismic data from the Gypsy test site in Oklahoma (a site originally established by British Petroleum). In this field example within a sandstone reservoir, we demonstrate the sensitivity of leaky mode amplitudes to source‐receiver location. Another telltale characteristic of continuity in the type of reservoir studied at the Gypsy test site, where there is a low shear velocity contrast between the host medium and the waveguide, is the head wave followed by the leaky mode.

An eigenfunction representation of deep waveguides with application to unconventional reservoirs

Geophysics ◽  
2021 ◽  
Vol 86 (6) ◽  
pp. T509-T521
Author(s):  
Owen Huff ◽  
Bin Luo ◽  
Ariel Lellouch ◽  
Ge Jin
Keyword(s):  
Finite Difference ◽  
Energy Distribution ◽  
Wave Energy ◽  
High Frequency ◽  
Guided Waves ◽  
Guided Wave ◽  
Low Velocity ◽  
Eagle Ford ◽  
Low Velocity Zone ◽  
Velocity Zone

Guided waves that propagate in deep low-velocity zones can be described using the displacement-stress eigenfunction theory. For a layered subsurface, these eigenfunctions provide a framework to calculate guided-wave properties at a fraction of the time required for fully numerical approaches for wave-equation modeling, such as the finite-difference approach. Using a 1D velocity model representing the low-velocity Eagle Ford Shale, an unconventional hydrocarbon reservoir, we verify the accuracy of the displacement eigenfunctions by comparing with finite-difference modeling. We use the amplitude portion of the Green’s function for source-receiver eigenfunction pairs as a proxy for expected guided-wave amplitude. These response functions are used to investigate the impact of the velocity contrast, reservoir thickness, and receiver depth on guided-wave amplitudes for discrete frequencies. We find that receivers located within the low-velocity zone record larger guided-wave amplitudes. This property may be used to infer the location of the recording array in relation to the low-velocity reservoir. We also study guided-wave energy distribution between the different layers of the Eagle Ford model and find that most of the high-frequency energy is confined to the low-velocity reservoir. We corroborate this measurement with field microseismic data recorded by distributed acoustic sensing fiber installed outside of the Eagle Ford. The data contain high-frequency body-wave energy, but the guided waves are confined to low frequencies because the recording array is outside the waveguide. We also study the energy distribution between the fundamental and first guided-wave modes as a function of the frequency and source depth and find a nodal point in the first mode for source depths originating in the middle of the low-velocity zone, which we validate with the same field data. The varying modal energy distribution can provide useful constraints for microseismic event depth estimation.

Elastic Guided Waves in Composite Pipes

2004 ◽  
Author(s):  
Younho Cho ◽  
Joseph L. Rose ◽  
Chong Myoung Lee ◽  
Gregory N. Bogan
Keyword(s):  
Guided Waves ◽  
Variational Calculus ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Guided Wave ◽  
Finite Element Software ◽  
Layer Composite ◽  
Superposition Technique ◽  
Composite Pipes ◽  
Iterate Process

An efficient technique for the calculation of guided wave dispersion curves in composite pipes is presented. The technique uses a forward-calculating variational calculus approach rather than the guess and iterate process required when using the more traditional partial wave superposition technique. The formulation of each method is outlined and compared. The forward-calculating formulation is used to develop finite element software for dispersion curve calculation. Finally, the technique is used to calculate dispersion curves for several structures, including an isotropic bar, two multi-layer composite bars, and a composite pipe.

Detection of guided waves between gas wells for reservoir characterization

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 38-49 ◽  
Author(s):  
Jorge O. Parra ◽  
Chris L. Hackert ◽  
Anthony W. Gorody ◽  
Valeri Korneev
Keyword(s):  
Seismic Waves ◽  
Guided Waves ◽  
Reservoir Characterization ◽  
Real Data ◽  
Dispersion Analysis ◽  
Guided Wave ◽  
Low Velocity ◽  
Gas Field ◽  
Potential Applications ◽  
Southeast Texas

Guided seismic waves can be used to predict continuity and discontinuity of reservoir structures between wells, with the low‐velocity beds acting as waveguides. We relate guided‐wave signatures to waveguide targets using experimental data acquired at the Stratton gas field in southeast Texas. The observed seismic data indicate the presence of trapped energy in low velocity shale markers between wells 145 and 151. Guided waves in the form of leaky modes are excited, transmitted, and detected in the low‐velocity shale markers at a well separation of 1730 ft (527 m). Dispersion analysis, modeling, frequency–amplitude depth curves, well logs, and lithological information all support the results. Specifically, the characterization of two low‐velocity shale markers, V2 and V5, demonstrates that V2 is more heterogeneous than V5 between the source well 151 and detector well 145. Finally, images of synthetic and real data show the potential applications of the guided‐wave technology as a tool for reservoir characterization.

Marine guided waves: Subbottom property estimation and filtering using physical modeling data

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. V303-V315 ◽  
Author(s):  
Jiannan Wang ◽  
Robert R. Stewart ◽  
Nikolay I. Dyaur ◽  
M. Lee Bell
Keyword(s):  
Wave Velocity ◽  
Physical Modeling ◽  
Guided Waves ◽  
Theoretical Calculations ◽  
Wave Dispersion ◽  
Guided Wave ◽  
S Wave ◽  
Seismic Surveys ◽  
Modeling Data ◽  
Estimation And Filtering

Marine guided waves are strongly dispersive and commonly observed in seismic surveys worldwide in areas of shallow water with a hard seafloor. They are energetic and can obscure deeper reflection signals. We have conducted several ultrasonic physical modeling experiments to observe marine guided waves. The guided-wave dispersion curves from these surveys fit theoretical calculations very well. We next developed a new method to extract the subbottom S-wave velocity and density from water column guided waves using least-squares inversion. We have also developed a dispersion-curve filter, in the velocity-frequency domain, to attenuate the guided waves. We then applied these techniques to the physical modeling data, which have different water depths and different subbottom materials. The extracted results (S-wave velocity, density, and water depth) match the actual values well. The dispersion-domain filter clarifies reflections by attenuating the guided waves, which benefits further processing and interpretation.

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