Junggar Basin 3D DAS-VSP Data Acquisition, Processing and Integrated Interpretation

DAS-VSP survey is increasingly recognized as a viable alternative to geophone arrays for downhole Vertical Seismic Profiling (VSP) data acquisition. To overcome the exploration challenges in the Junggar Basin, the largest scale onshore 3D DAS-VSP survey project in China has been conducted using armored fibre optical cables outside casing and inside casing.

The 3D DAS-VSP data acquisition and processing have provided us with many challenges. We deployed the armored optical cables outside casing and inside casing in the same well, and successfully completed the acquisition of the 3D DAS-VSP data from 2 optical cables with good quality data. The processing results of the 3D DAS-VSP data provided high-resolution structural image around the borehole. The accurate time-depth relationship, formation velocity, deconvolution operator, spherical diffusion compensation factor, absorption attenuation factor and anisotropy parameters have also obtained. The 3D DAS-VSP imaging using angular domain Gaussian beam prestack migration method was applied to the 3D DAS-VSP data set. The Q value obtained from the uphole data and 3D DAS-VSP data was used to constrain the conventional PSTM velocity model, and the borehole driven QPSTM was conducted on the surface 3D seismic data around borehole area with significant improvement of the surface 3D seismic imaging.