oa Studies of Onshore Hill DAS 3D VSP Processing

In-well distributed acoustic sensing (DAS) is a high cost-effective means for acquiring borehole seismic data and imaging around borehole. We selected a gas well in the hilly area of the Sichuan Basin for acquiring DAS 3D VSP during 3D surface seismic acquisition, greatly reducing costs. The hill 3D DAS VSP has several significant characteristics, such as high density, various noises and sparse survey (360m x 40m). KL transform, Tau-P domain deconvolution, and anisotropic diffusion filtering methods can significantly improve the signal-to-noise ratio of DAS VSP. 3D VSP imaging adopts 3D multi-stencils fast marching method (MSMF) for grid ray-tracing and based travel time table for imaging, which effectively improves the efficiency and accuracy of DAS 3D VSP grid ray-tracing calculation, making the 3D VSP imaging more stable and less arcs.