Zero‐phasing seismic data without wells in offshore West Africa: Reducing uncertainty and variability of the wavelet

Abstract

Traditionally, many companies have zero‐phased seismic data using operators based on wavelets estimated from well matching. However, in new areas of exploration, other methods must be used. A data example from deep‐water West Africa is discussed in which the use of two independent methods of estimating the wavelet (physical modeling and statistical evaluation) allows for increased confidence in the resulting zero‐phasing. The two methods are complimentary in that they compensate for the inadequacies of each other's assumptions. The combination of the two to reduce uncertainty in wavelet estimation is the main objective. The acquisition and processing of the data are of great importance in ensuring wavelet stability in the section and allowing the wavelet estimation methods to be used reliably. Careful application of gapped deconvolutions in the processing sequence allows for wavelet compression and consistency over large areas of data that can then be zero‐phased using a single operator, even though the data covers diverse geology and water depths.