The Interferometric Fresnel Zone

We present a way to implement the virtual source (VS) method in a real scenario where a summation over all the available sources in the dataset may not be the optimal solution. Because the main contributions to the interferometric data construction come from sources at stationary locations, a target-oriented source selection could reduce artefacts improving the SNR. The requirements for a correct virtual-source gather construction in a constant velocity medium are summarized. A quantitative explanation of these qualitative considerations is given by the aim of the Fresnel zone concept. The stationary zone for VTI media is obtained both in case of zero and non-zero virtual offset (distance between VS and receiver) redatuming. The advantages of a partial summation just over the Fresnel zone are discussed by using an elastic 2D finite difference synthetic data example.