Vertical seismic profiling using distributed acoustic sensing with scatter‐enhanced fibre‐optic cable at the Cu–Au New Afton porphyry deposit, British Columbia, Canada

On September 16th 2018 a Danish earthquake of local magnitude 3.7 was recorded by distributed acoustic sensing (DAS) in a ~23 km long fibre-optic cable. The data are used to study how well DAS can be used as a supplement to conventional seismological data in earthquake localisation. One of the goals in this study is extracting a small subset of traces with clear P and S phases to use in an earthquake localisation, from the 11144 traces the DAS system provide. The timing in the DAS data might not be reliable, and therefore differences in arrival times of S and P are used instead of the exact arrival times. The DAS data set is generally noisy and with a low signal-to-noise ratio (SNR). It is examined whether stacking can be used to improve SNR. The SNR varies a lot along the fibre-optic cable, and at some distances, it is so small that the traces are useless. Stacking methods for improving SNR are presented.A field test at two location sites of the fibre-optic cable was conducted with the purpose of comparing DAS data with seismometer data. At the field sites, hammer shots were recorded by a small array of three STS-2 sensors located in a line parallel to the fibre-optic cable. The recordings generally show good consistency between the two data sets.&#160; In addition, the field tests are used to get a better understanding of the noise sources in the DAS recording of the earthquake. There are many sources of noise in the data set. The most prominent are a line of windmills that cross the fibre-optic cable and people walking in the building where the detector is located. Also, the coupling between the fibre-optic cable and the ground varies along the cable length due to varying soil type and wrapping around the fibre-optic cable, which is also evident in field test data. Furthermore, the data from the field tests are used to calibrate the location of the fibre-optic cable, which is necessary for using the DAS data in an earthquake localisation. Data processing is done in Matlab and SEISAN.

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Vertical seismic profiling using distributed acoustic sensing in a hydrofrac treatment well

10.1190/segam2014-1559.1 ◽

2014 ◽

Cited By ~ 2

Author(s):

Sudhish K. Bakku* ◽

Michael Fehler ◽

Peter Wills ◽

Jeff Mestayer ◽

Albena Mateeva ◽

...

Keyword(s):

Acoustic Sensing ◽

Seismic Profiling ◽

Vertical Seismic Profiling ◽

Distributed Acoustic Sensing

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Borehole Seismic: Essential Contributions Over the Oilfield Lifecycle

10.2118/204889-ms ◽

2021 ◽

Author(s):

Rajeev Kumar ◽

Pierre Bettinelli

Keyword(s):

Hydraulic Fracturing ◽

Real Time ◽

Depth Information ◽

Acoustic Sensing ◽

Seismic Profiling ◽

Production Phase ◽

Vertical Seismic Profiling ◽

Wide Range ◽

Distributed Acoustic Sensing ◽

Borehole Seismic

Abstract During the evolution of the petroleum industry, surface seismic imaging has played a critical role in reservoir characterization. In the early days, borehole seismic (BHS) was developed to complement surface seismic. However, in the last few decades, a wide range of BHS surveys has been introduced to cater to new and unique objectives over the oilfield lifecycle. In the exploration phase, vertical seismic profiling (VSP) provides critical time-depth information to bridge time indexed subsurface images to log/reservoir properties in depth. This information can be obtained using several methods like conventional wireline checkshot or zero-offset vertical seismic profiling (ZVSP), seismic while drilling (SWD) or distributed acoustic sensing (DAS) techniques. SWD is a relatively new technique to record real-time data using tool deployed in the bottomhole assembly without disturbing the drilling. It helps to improve decision making for safer drilling especially in new areas in a cost-effective manner. Recently, a breakthrough technology, distributed acoustic sensing (DAS), has been introduced, where data are recorded using a fiber-optic cable with lots of saving. ZVSP also provides several parameters like, attenuation coefficient (Q), multiples prediction, impedance, reflectivity etc., which helps with characterizing the subsurface and seismic reprocessing. In the appraisal phase, BHS applications vary from velocity model update, anisotropy estimation, well- tie to imaging VSPs. The three-component VSP data is best suited for imaging and amplitude variation with offset (AVO) due to several factors like less noise interference due to quiet downhole environment, higher frequency bandwidth, proximity to the reflector, etc. Different type of VSP surveys (offset, walkaway, walkaround etc.) were designed to fulfill objectives like imaging, AVO, Q, anisotropy, and fracture mapping. In the development phase, high-resolution images (3D VSP, walkaway, or crosswell) from BHS surveys can assist with optimizing the drilling of new wells and, hence reduce costs. it can help with landing point selection, horizontal section placement, and refining interpretation for reserve calculation. BHS offers a wide range of surveys to assist the oilfield lifecycle during the production phase. Microseismic monitoring is an industry-known service to optimize hydraulic fracturing and is the only technique that captures the induced seismicity generated by hydraulic fracturing and estimate the fracture geometry (height, width, and azimuth) and in real time. During enhanced oil recovery (EOR) projects, BHS can be useful to optimize the hydrocarbon drainage strategies by mapping the fluid movement (CO2, water, steam) using time-lapse surveys like walkaway, 3D VSP and/or crosswell. DAS has brought a new dimension to provide vital information on injection or production evaluation, leak detection, flow behind tubing, crossflow diagnosis, and cement evaluation during production phase. This paper highlights the usage of BHS over the lifecycle of the oilfield.

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Repeatability Analysis of Time-Lapse Vertical Seismic Profiling Data Acquired Using Distributed Acoustic Sensing: Harvey, South-West Hub

10.3997/2214-4609.202011591 ◽

2020 ◽

Author(s):

S. Yavuz ◽

K. Tertyshnikov ◽

R. Pevzner ◽

K.G. Vei

Keyword(s):

Time Lapse ◽

Acoustic Sensing ◽

Seismic Profiling ◽

Vertical Seismic Profiling ◽

South West ◽

Distributed Acoustic Sensing

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Seismic imaging of porphyry deposits with distributed acoustic sensing of fibre-optic cables: a summary of results at the New Afton Cu-Au mine, British Columbia

10.4095/327942 ◽

2021 ◽

Author(s):

G Bellefleur ◽

E Schetselaar ◽

D White

Keyword(s):

British Columbia ◽

Seismic Imaging ◽

Fibre Optic ◽

Acoustic Sensing ◽

Porphyry Deposits ◽

Distributed Acoustic Sensing

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Wireline distributed acoustic sensing allows 4.2 km deep vertical seismic profiling of the Rotliegend 150 °C geothermal reservoir in the North German Basin

Solid Earth ◽

10.5194/se-12-521-2021 ◽

2021 ◽

Vol 12 (2) ◽

pp. 521-537

Author(s):

Jan Henninges ◽

Evgeniia Martuganova ◽

Manfred Stiller ◽

Ben Norden ◽

Charlotte M. Krawczyk

Keyword(s):

Elevated Temperatures ◽

Volcanic Rocks ◽

Vertical Component ◽

Geothermal Reservoir ◽

Fiber Optic Sensor ◽

Acoustic Sensing ◽

Seismic Profiling ◽

Vertical Seismic Profiling ◽

Recorded Data ◽

Distributed Acoustic Sensing

Abstract. We performed so-far-unprecedented deep wireline vertical seismic profiling at the Groß Schönebeck site with the novel method of distributed acoustic sensing (DAS) to gain more detailed information on the structural setting and geometry of the geothermal reservoir, which is comprised of volcanic rocks and sediments of Lower Permian age. During the survey of 4 d only, we acquired data for 61 source positions using hybrid wireline fiber-optic sensor cables deployed in two 4.3 km deep, already existing wells. While most of the recorded data have a very good signal-to-noise ratio, individual sections of the profiles are affected by characteristic coherent noise patterns. This ringing noise results from incomplete coupling of the sensor cable to the borehole wall, and it can be suppressed to a large extent using suitable filtering methods. After conversion to strain rate, the DAS data exhibit a high similarity to the vertical component data of a conventional borehole geophone. We derived accurate time–depth relationships, interval velocities, and corridor stacks from the recorded data. Based on integration with other well data and geological information, we show that the top of a porous and permeable sandstone interval of the geothermal reservoir can be identified by a positive reflection event. Overall, the sequence of reflection events shows a different character for both wells explained by lateral changes in lithology. The top of the volcanic rocks has a somewhat different seismic response in both wells, and no clear reflection event is obvious at the postulated base of the volcanic rocks, so that their thickness cannot be inferred from individual reflection events in the seismic data alone. The DAS method enabled measurements at elevated temperatures up to 150 ∘C over extended periods and led to significant time and cost savings compared to deployment of a conventional borehole geophone string. This wireline approach finally suggests significant implications for observation options in old wells for a variety of purposes.

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Observing avalanche dynamics with Distributed Acoustic Sensing

10.5194/egusphere-egu21-16562 ◽

2021 ◽

Author(s):

Andreas Fichtner ◽

Pascal Edme ◽

Patrick Paitz ◽

Nadja Lindner ◽

Michael Hohl ◽

...

Keyword(s):

Spatial Resolution ◽

Flow Regimes ◽

Dynamic Strain ◽

Seismic Signals ◽

Fibre Optic ◽

Snow Avalanches ◽

Acoustic Sensing ◽

Fibre Optic Cable ◽

Distributed Acoustic Sensing ◽

Seismic Instrumentation

Avalanche research requires comprehensive measurements of sudden and rapid snow mass movement that is hard to predict. Automatic cameras, radar and infrasound sensors provide valuable observations of avalanche structure and dynamic parameters, such as velocity. Recently, seismic sensors have also gained popularity, because they can monitor avalanche activity over larger spatial scales. Moreover, seismic signals elucidate rheological properties, which can be used to distinguish different types of avalanches and flow regimes. To date, however, seismic instrumentation in avalanche terrain is sparse. This limits the spatial resolution of avalanche details, needed to characterise flow regimes and maximise detection accuracy for avalanche warning.As an alternative to conventional seismic instrumentation, we propose Distributed Acoustic Sensing (DAS) to measure avalanche-induced ground motion. DAS is based on fibre-optic technology, which has previously been used already for environmental monitoring, e.g., of snow avalanches. Thanks to recent technological advances, modern DAS interrogators allow us to measure dynamic strain along a fibre-optic cable with unprecedented temporal and spatial resolution. It therefore becomes possible to record seismic signals along many kilometres of fibre-optic cables, with a spatial resolution of a few metres, thereby creating large arrays of seismic receivers. We test this approach at an avalanche test site in the Valle&#233; de la Sionne, in the Swiss Alps, using an existing 700 m long fibre-optic cable that is permanently installed underground for the purpose of data transfer of other, independent avalanche measurements.During winter 2020/2021, we recorded numerous snow avalanches, including several which reached the valley bottom, travelling directly over the cable during runout. The DAS recordings show clear seismic signatures revealing individual flow surges and various phases/modes that may be associated with roll waves and avalanche arrest. We compare our observations to state-of-the-art radar and seismic measurements which ideally complement the DAS data.Our initial analysis highlights the suitability of DAS-based monitoring and research for avalanches and other hazardous granular flows. Moreover, the clear detectability of avalanche signals using existing fibre-optic infrastructure of telecommunication networks opens the opportunity for unrivalled warning capabilities in Alpine environments.

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