Encoding techniques for multiple source point seismic data acquisition

Abstract

Recent advances in vibrator electronics have made the use of encoded sweeps for multiple source point data acquisition possible in an operational setting. Alternatives to existing operational multiple source point data acquisition techniques, using complementary series and E‐codes, are developed in this paper. Most existing techniques are, at each source point, a series of linear sweeps of predetermined polarity that enables the cancellation of the contributions from the other source points in processing. The complementary series techniques developed here also choose polarities such that the contributions from other source points can be cancelled. Pairs of E‐codes have been found that produce no crosscorrelation, which makes it possible to use E‐codes to produce a dual source point technique that is fundamentally different from the more conventional techniques. Field tests are carried out using E‐codes in dual source point schemes. Records from the respective source points are readily separated from the composite data collected and compared with records produced by a linear sweep from a single source point. Harmonic distortion appears to be the major limiting factor; however, record quality indicates that E‐codes can be used in operational multiple source point data acquisition.