Estimation of seismic velocity and layer thickness of Eagle Ford Formation using microseismic guided waves in downhole distributed acoustic sensing records

2020 ◽  
Author(s):  
Bin Luo ◽  
Ge Jin ◽  
Ariel Lellouch
Keyword(s):  
Layer Thickness ◽  
Guided Waves ◽  
Seismic Velocity ◽  
Eagle Ford ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing

Distributed acoustic sensing for seismic monitoring in challenging environments

2020 ◽  
Author(s):  
Zack Spica ◽  
Takeshi Akuhara ◽  
Gregory Beroza ◽  
Biondo Biondi ◽  
William Ellsworth ◽  
...  
Keyword(s):  
Seismic Velocity ◽  
Velocity Estimation ◽  
Motion Sensors ◽  
Recording Technology ◽  
Acoustic Sensing ◽  
Seismic Properties ◽  
Seismic Recording ◽  
Distributed Acoustic Sensing ◽  
Geotechnical Information ◽  
Observation Bias

<p>Our understanding of subsurface processes suffers from a profound observation bias: ground-motion sensors are rare, sparse, clustered on continents and not available where they are most needed. A new seismic recording technology called distributed acoustic sensing (DAS), can transform existing telecommunication fiber-optic cables into arrays of thousands of sensors, enabling meter-scale recording over tens of kilometers of linear fiber length. DAS works in high-pressure and high-temperature environments, enabling long-term recordings of seismic signals inside reservoirs, fault zones, near active volcanoes, in deep seas or in highly urbanized areas.</p><p>In this talk, we will introduce this laser-based technology and present three recent cases of study. The first experiment is in the city of Stanford, California, where DAS measurements are used to provide geotechnical information at a scale normally unattainable (i.e., for each building) with traditional geophone instrumentation. In the second study, we will show how downhole DAS passive recordings from the San Andreas Fault Observatory at Depth can be used for seismic velocity estimation. In the third research, we use DAS (in collaboration with Fujitec) to understand the ocean physics and infer seismic properties of the seafloor under a 100 km telecommunication cable.</p>

Fracture properties estimation using distributed acoustic sensing recording of guided waves in unconventional reservoirs

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. M85-M95 ◽  
Author(s):  
Ariel Lellouch ◽  
Mark A. Meadows ◽  
Tamas Nemeth ◽  
Biondo Biondi
Keyword(s):  
Large Scale ◽  
Guided Waves ◽  
Geometric Analysis ◽  
Unconventional Reservoirs ◽  
Low Velocity ◽  
Sh Waves ◽  
Hydraulic Stimulation ◽  
Acoustic Sensing ◽  
Arrival Times ◽  
Distributed Acoustic Sensing

Perforation shots excite guided waves that propagate in a low-velocity unconventional shale reservoir. They have a frequency content of up to 700 Hz and are dispersive. We have analyzed horizontal crosswell perforation shots recorded by a distributed acoustic sensing (DAS) array. As guided waves propagate through a previously stimulated area, we observe a dramatic influence on the guided SH waves in the form of delayed arrival times, scattering, phase incoherency, and loss of amplitude and frequency. The leaky compressional waves undergo a gradual slowdown. Using a simple geometric analysis of the spatial locations of the distortions in the direct arrivals of the guided SH waves, we can estimate the half-lengths of the induced fractures, which range from 50% to 75% of the distance between the perforated and monitoring wells. Furthermore, we find that the propagation disturbances originate from the middle of the stimulated area. Other diffracted signals, notably from frac plugs, are clearly visible in the data. We report the first large-scale use of DAS records of guided waves. Their potential for high-resolution imaging and inversion of subsurface properties before and after hydraulic stimulation opens new possibilities for the use of seismology in optimizing production from unconventional reservoirs.

Continuous source system and distributed acoustic sensing for reservoir to crust monitoring

2020 ◽  
Author(s):  
Takeshi Tsuji ◽  
Tatsunori Ikeda ◽  
Koshun Yamaoka
Keyword(s):  
Monitoring System ◽  
Field Experiments ◽  
Seismic Velocity ◽  
Seismic Source ◽  
Seismic Signal ◽  
Geothermal Field ◽  
High Temporal Resolution ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Continuous Source

<p><strong>We have developed a permanent seismic monitoring system using a continuous seismic source and distributed acoustic sensing (DAS). </strong><strong>The active seismic source system continuously </strong><strong>generates waveforms </strong><strong>with wide frequency range. By stacking the continuous waveforms, our monitoring system improves signal-to-noise ratio of the seismic signal. Thus, less-energy vibration using</strong><strong> s</strong><strong>mall-size source could be utilized for the exploration of deeper geological targets. Presently, we have deployed the small-size monitoring source system in the Kuju geothermal field in the northeast Kyushu Island, Japan. Although our monitoring source system is small and generates high frequency vibrations (10-20Hz), the signal propagated ></strong><strong>80 </strong><strong>km distance using two-month continuous source data. Our field experiments demonstrate that variation of seismic velocity of the crust could be identified with high accuracy (~0.01 %). </strong><strong>To record the monitoring signal from continuous source system, we need to deploy seismometers. Deployment of many seismometers increase spatial resolution of the monitoring results. Recently, we have deployed the DAS system close to the continuous seismic source system. Using DAS, dense and long seismometer network can be realized, and we succeeded to identify the temporal variation of seismic velocity. By using both continuous source and DAS, we are able to monitor wide area with lower cost. </strong><strong>Our monitoring system could accurately monitor the larger-scale crust and smaller-scale reservoir in high temporal resolution.</strong></p>

scholarly journals Fracture detection and imaging through relative seismic velocity changes using distributed acoustic sensing and ambient seismic noise

2017 ◽  
Vol 36 (12) ◽  
pp. 1009-1017 ◽  
Author(s):  
Stephanie R. James ◽  
Hunter A. Knox ◽  
Leiph Preston ◽  
James M. Knox ◽  
Mark C. Grubelich ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Seismic Velocity ◽  
Ambient Seismic Noise ◽  
Fracture Detection ◽  
Acoustic Sensing ◽  
Seismic Velocity Changes ◽  
Distributed Acoustic Sensing ◽  
Velocity Changes

Velocity‐Based Earthquake Detection Using Downhole Distributed Acoustic Sensing—Examples from the San Andreas Fault Observatory at Depth

2019 ◽  
Vol 109 (6) ◽  
pp. 2491-2500 ◽  
Author(s):  
Ariel Lellouch ◽  
Siyuan Yuan ◽  
William L. Ellsworth ◽  
Biondo Biondi
Keyword(s):  
San Andreas Fault ◽  
Seismic Velocity ◽  
Incidence Angle ◽  
Signal To Noise Ratio ◽  
Plane Waves ◽  
Detection Algorithm ◽  
Angle Of Incidence ◽  
Acoustic Sensing ◽  
San Andreas ◽  
Distributed Acoustic Sensing

Abstract Conventional seismographic networks sparsely sample the wavefields excited by earthquakes. Thus, standard event detection is conducted by analyzing separate stations and merging their results. Emerging distributed acoustic sensing recording technologies allow for unbiased spatial sampling of the wavefield and, as a result, array‐based processing of the recorded signals. Using a cemented fiber in the San Andreas Fault Observatory at Depth main hole, 800 virtual receivers are sampled at a 1 m interval from the surface to 800 m depth. Recorded earthquakes are approximated as plane waves reaching the bottom of the array first. Following this assumption, the relative travel times of the recorded event depend on the local velocity at the array location and the angle of incidence at which the planar wavefront reaches it. Given the seismic velocity, a newly proposed detection algorithm amounts to a single‐parameter scan of the incidence angle and measurement of data coherency along the different possible travel‐time curves. Using the entire recording array, a much higher effective signal‐to‐noise ratio can be obtained when compared to individual channel processing. About 20 days of recorded seismic activity from the San Andreas Fault is analyzed. Using a downhole single array, the majority of cataloged events in the area are detected. In addition, a previously unknown event is unveiled. We estimate its magnitude at roughly −0.5.

Detecting Leaks in Abandoned Gas Wells with Fibre-Optic Distributed Acoustic Sensing

2014 ◽  
Author(s):  
K. Boone ◽  
A. Ridge ◽  
R. Crickmore ◽  
D. Onen
Keyword(s):  
Fibre Optic ◽  
Gas Wells ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing

scholarly journals Low‐Magnitude Seismicity With a Downhole Distributed Acoustic Sensing Array—Examples From the FORGE Geothermal Experiment

2020 ◽  
Vol 126 (1) ◽  
Author(s):  
A. Lellouch ◽  
R. Schultz ◽  
N.J. Lindsey ◽  
B.L. Biondi ◽  
W.L. Ellsworth
Keyword(s):  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Low Magnitude

Combining Distributed Acoustic Sensing and Beamforming in a Volcanic Environment on Mount Meager, British Columbia.

2021 ◽  
Author(s):  
Sara Klaasen ◽  
Patrick Paitz ◽  
Jan Dettmer ◽  
Andreas Fichtner
Keyword(s):  
British Columbia ◽  
Power Distribution ◽  
High Frequency ◽  
Low Frequency ◽  
Volcanic Tremor ◽  
Extreme Environment ◽  
Volcanic Complex ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Volcanic Environment

<p>We present one of the first applications of Distributed Acoustic Sensing (DAS) in a volcanic environment. The goals are twofold: First, we want to examine the feasibility of DAS in such a remote and extreme environment, and second, we search for active volcanic signals of Mount Meager in British Columbia (Canada). </p><p>The Mount Meager massif is an active volcanic complex that is estimated to have the largest geothermal potential in Canada and caused its largest recorded landslide in 2010. We installed a 3-km long fibre-optic cable at 2000 m elevation that crosses the ridge of Mount Meager and traverses the uppermost part of a glacier, yielding continuous measurements from 19 September to 17 October 2019.</p><p>We identify ~30 low-frequency (0.01-1 Hz) and 3000 high-frequency (5-45 Hz) events. The low-frequency events are not correlated with microseismic ocean or atmospheric noise sources and volcanic tremor remains a plausible origin. The frequency-power distribution of the high-frequency events indicates a natural origin, and beamforming on these events reveals distinct event clusters, predominantly in the direction of the main peaks of the volcanic complex. Numerical examples show that we can apply conventional beamforming to the data, and that the results are improved by taking the signal-to-noise ratio of individual channels into account.</p><p>The increased data quantity of DAS can outweigh the limitations due to the lower quality of individual channels in these hazardous and remote environments. We conclude that DAS is a promising tool in this setting that warrants further development.</p>

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