Multi-well 3D DAS VSPs: Illumination and imaging beyond the wellbores

Zhan, Ge; Nahm, Jay

doi:10.1190/segam2020-3426032.1

Cited by 9 publications

(1 citation statement)

References 6 publications

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“…Measurements with a fibre-optic cable installed along the casing or behind the tubing are widely and successfully applied for borehole seismic data acquisition. 3D vertical seismic profiling (VSP) imaging results with permanent cable installation include applications for oil and gas exploration (Jiang et al, 2016;Shultz and Simmons, 2019;Zhan and Nahm, 2020), the monitoring of CO 2 reservoirs (Humphries et al, 2015;Götz et al, 2018;Correa et al, 2019;Wilson et al, 2021), and mineral exploration and mining (Bellefleur et al, 2020). Nevertheless, in a vast number of already drilled and cased boreholes, only measurements with a wireline logging cable are feasible.…”

Section: Introductionmentioning

confidence: 99%

3D deep geothermal reservoir imaging with wireline distributed acoustic sensing in two boreholes

et al. 2022

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Abstract. Geothermal exploration will help move towards a low-carbon economy and provide a basis for green and sustainable growth. The development of new practical, reliable methods for geophysical characterization of a reservoir has the potential to facilitate a broader application of deep geothermal energy. At the Groß Schönebeck in situ laboratory, a unique vertical seismic profiling (VSP) dataset was recorded in two 4.3 km deep geothermal boreholes using fibre-optic cables in early 2017. The experiment set-up consisted of 61 vibrator points organized in a spiral pattern around the well site to ensure a proper offset and azimuth distribution in the target reservoir section. Data were processed using a standard workflow for VSP. As a result, a detailed three-dimensional 0.75km×1km×4.5 km image around the existing boreholes was created using the Kirchhoff migration algorithm with restricted aperture. The imaging resolved small-scale features in the reservoir essential for the future exploration of the geothermal research site. Borehole data with vertical resolution up to 16 m revealed the existing depth variations of the Elbe reservoir sandstone horizon at 4.08–4.10 km depth and indications of an unconformity in the area where we expect volcanic rocks. In addition, in the borehole data a complex interlaying with numerous pinch-outs in the Upper Rotliegend reservoir section (3.8 to 4 km depth) was discovered. Thereby, we demonstrate that wireline fibre-optic data can significantly contribute to exploration by providing an efficient and reliable method for deep geothermal reservoir imaging.

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