Distributed acoustic sensing (DAS) to velocity transform and its benefits

Sayed, Ali; Ali, Shujaat; Stewart, Robert R.

doi:10.1190/segam2020-3424622.1

Cited by 18 publications

(2 citation statements)

References 6 publications

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“…We generated a 1D P-wave velocity profile from the first-break picks of the zero-offset shot. The Q attenuation was calculated by the spectral ratio method after applying the gauge length correction as outlined in [15,16]. Compared to the well logs derived from the well nearby, the velocity profile was edited to include major geological formations in the Permian Basin (Figure 6a).…”

Section: Methodsmentioning

confidence: 99%

3D VSP Imaging Using DAS Recording of P- and S-Waves in Vertical and Lateral Well Sections in West Texas

Wang,

Stewart

2024

Sensors

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A 3D vertical seismic profiling (VSP) survey was acquired using a distributed acoustic sensing (DAS) system in the Permian Basin, West Texas. In total, 682 shot points from a pair of vibroseis units were recorded using optical fibers installed in a 9000 ft (2743 m) vertical part and 5000 ft (1524 m) horizontal reach of a well. Transmitted and reflected P, S, and converted waves were evident in the DAS data. From first-break P and S arrivals, we found average P-wave velocities of approximately 14,000 ft/s (4570 m/s) and S-wave velocities of 8800 ft/s (3000 m/s) in the deep section. We modified the conventional geophone VSP processing workflow and produced P–P reflection and P–S volumes derived from the well’s vertical section. The Wolfcamp formation can be seen in two 3D volumes (P–P and P–S) from the vertical section of the well. They cover an area of 3000 ft (914 m) in the north–south direction and 1500 ft (460 m) in the west–east direction. Time slices showed coherent reflections, especially at 1.7 s (~11,000 ft), which was interpreted as the bottom of the Wolfcamp formation. Vp/Vs values from 2300 ft (701 m) –8800 ft (2682 m) interval range were between 1.7 and 2.0. These first data provide baseline images to compare to follow-up surveys after hydraulic fracturing as well as potential usefulness in extracting elastic properties and providing further indications of fractured volumes.

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Section: Methodsmentioning

confidence: 99%

3D VSP Imaging Using DAS Recording of P- and S-Waves in Vertical and Lateral Well Sections in West Texas

Wang,

Stewart

2024

Sensors

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“…The gamma ray measurement at this interval might be influenced by changes in casing sections at 69 ft (end of Conductor section; grey inverted triangle) and 704 ft (end of Surface section; black inverted triangle). Beneath the basement contact, a gamma ray log drops at about 3080 ft, as reported by the lithology log, which indicates the lithological change from granite to granodiorite with a transition from 3060 ft to 3100 ft. We applied the gauge-length correction [15,16] to the DAS data to avoid mis-estimation. The gauge length used in the WVSP acquisition was 10 m (~32.80 ft).…”

Section: Velocity and Attenuation Profilesmentioning

confidence: 99%

Subsurface Imaging by a Post-Stimulation Walkaway Vertical Seismic Profile Using Distributed Acoustic Sensing at the Utah FORGE Enhanced Geothermal System Site

Wang,

Stewart

2024

Energies

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A 2D walkway vertical seismic profile (VSP) survey was conducted using a distributed acoustic sensing (DAS) system in southwest Utah, which is part of an enhanced geothermal system (EGS) project. The VSP was undertaken to obtain detailed structural information for a better understanding of the area’s subsurface geology and associated fracture development. By combining a 3D composite velocity model from previous studies and considering the complex geological structure beneath this region, we processed the data to create P-P depth image. We also modified the interval Q calculation using a moving window over the gauge-length corrected DAS record to generate the velocity profile and the comparable interval attenuation curve. The correlated P-P images from two DAS records successfully indicate not only the main contact between shallow unconsolidated sediments and the metamorphic basement rocks at 2650 ft (807.72 m) but also several distinct reflections related to the geological contacts. The refined velocity profiles and the depth images can provide baseline results for further seismic modeling and time-lapse imaging.

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Distributed Acoustic Sensing to Velocity Transform for Vertical Seismic Profiling Applications

Sayed,

Khaitan,

Martinez

et al. 2024

Geophysical Monograph Series

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Distributed acoustic sensing (DAS) to velocity transform and its benefits

Cited by 18 publications

References 6 publications

3D VSP Imaging Using DAS Recording of P- and S-Waves in Vertical and Lateral Well Sections in West Texas

3D VSP Imaging Using DAS Recording of P- and S-Waves in Vertical and Lateral Well Sections in West Texas

Subsurface Imaging by a Post-Stimulation Walkaway Vertical Seismic Profile Using Distributed Acoustic Sensing at the Utah FORGE Enhanced Geothermal System Site

Distributed Acoustic Sensing to Velocity Transform for Vertical Seismic Profiling Applications

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