ABSTRACT

Receiver grouping is commonly used in marine towed-streamer seismic acquisition. Measurements from several receivers in a group are stacked to increase the signal-to-noise ratio of the resulting data and form an analog spatial antialiasing filter. I propose a method for extracting inline derivatives of the wavefield as additional measurements from the groups. This is achieved by multiplying the signal from the individual receivers in a group with predefined weights that corresponds to a finite-difference (FD) operator. The inline derivative(s) makes it possible to use multichannel sampling theorems to reconstruct the signal on a denser grid. Extraction of FD data from clusters of receivers is not a new concept, but I find that, by using the geometry of conventional streamer groups, it is possible to obtain FD data which are well suited for multichannel interpolation. The key to finding suitable FD operators is to recognize that it is not the ideal differentiation response we seek, but the impulse response of the group multiplied with the ideal differentiation response. Furthermore, under a Gaussian noise assumption, I derive formulas for the resulting noise level from sinc and higher order sinc interpolations. I find that the random noise level in the reconstructed data, when using higher order sinc interpolation, is expected to be higher than when using conventional sinc interpolation and will vary with respect to the distance from the original sampling points. The statistical analysis shows that it is beneficial to find FD operators with as small an L2 norm as possible. A synthetic example shows that the proposed method of extracting FD operators and subsequent interpolation works very well. I foresee that the proposed method can be used to reduce the density of receivers (hydrophones or geophones) when designing new streamers or with existing equipment to improve the inline sampling.

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