Estimation of Surface Impulse Response Data from Walkaway VSP Measurements

VSP imaging suffers from poor illumination and imaging artifacts away from the well trajectory. Imaging of the downgoing surface multiples is one of the approaches suggested in literature to increase the illumination area for the VSP data. We propose a new method to image the 2D walkaway VSP data, which includes estimation of the full surface impulse response from the 2D VSP data. The method utilizes both the upgoing and downgoing wavefields to reconstruct a pseudo-surface impulse response using a hybrid convolution-sparse inversion approach. The two-step method contributes in reconstructing the complimentary images: one near the well and the other one away from the well. This new method suffers from relatively little crosstalk compared to interferometric redatuming. Also, it will give us the full surface impulse response, including surface and internal multiples. This means that all existing tools for multiple removal and imaging surface seismic data can be applied to our result.