Source-side spatial wavefield gradients in land seismic exploration

Abstract

The recording of seismic data using arrays of densely spaced receivers enables the estimation of the spatial gradient components of the wavefield, in addition to the acquisition of conventional translational motion. We have extended the concept of array-based receiver-side gradiometry to the source-side and investigated the potential of combining source- and receiver-side gradient estimates for land seismic exploration. The robustness of array-based gradient source formation is demonstrated with a field data reciprocity experiment. We apply a gradient-based elastic wavefield decomposition technique to small arrays of densely spaced vertically and horizontally oriented force sources and determine with synthetic and field data examples that the processing of data obtained from multicomponent source arrays allows us to simulate a composite source that theoretically only emits S-waves at all emergence angles. A promising application of the gradient-based S-wave source is downhole S-wave imaging. Finally, by combining source- and receiver-side gradient estimates, 49C seismic data can be obtained comprising three translational components, three rotational components, and one divergence component on the source and receiver side. This concept could have a significant potential to enhance the acquisition and processing of data from locally dense arrays in land seismic exploration.