From geophone arrays to point receivers: Implications for sensor and land survey design Available to Purchase

Raw land seismic data acquired with point sensors has lower signal-to-noise ratio (SNR) than that acquired using geophone arrays due to noise attenuation in the array. However, the benefits of trace density and unaliased wavefield sampling for denoise and image resolution, combined with the ease of nodal deployments, mean that land seismic acquisition designs are trending towards denser single-sensor acquisition. Various approaches have been taken to try and obtain some of the benefits of arrays in terms of field data SNR via single-sensor acquisition. We show that replacing a geophone array with a single high-sensitivity point-receiver does not achieve this objective as the improved sensitivity only benefits system noise and has no effect on other signal perturbations (e.g., ambient noise) which are the dominant error source in land seismic data. Denser single-sensor acquisition enables SNR improvement: i) as more noise becomes coherent and can be attenuated using simple processing techniques; ii) there is no high-frequency signal attenuation due to the averaging effect of the array; and iii) perturbations (e.g. inter-element statics) are not “baked-in” to the field data allowing for correct handling in processing. These benefits are achieved without a one-to-one replacement of cabled-array sensor elements with point sensors, so the overall receiver-side effort for equivalent data quality is lower with dense single-sensor acquisition. We use data from a recent field test where 546 nodes were deployed in a 25m x 20m pattern at 1m spacing to illustrate some differences between single-sensor and array data.