Geophone Noise Attenuation and Wave-field Separation Using a Multi-dimensional Decomposition Technique

Perhaps the largest single obstacle to overcome in wave-field separation of P-Z data is the presence of noise energy (non P-wave specific) on the geophone that is not present on the hydrophone. In general, the noise manifests as coherent energy on common receiver gathers with moveout characteristics of converted wave velocity, and with relatively random phase and amplitude on shot gathers. Here we introduce a new method for processing dual sensor data, particularly in deep water, that includes intrinsic removal of V(z) noise as well as enhancing the wave-field separation. This method is based on a decomposition of data simultaneously into dip and frequency while retaining temporal locality. This energy has often been associated with acquisition integrity related issues such as coupling and phone orientation. Only recently, alternative explanations have been developed that describe a mechanism that will produce exactly the same type of energy (Paffenholz et al., 2006a, 2006b). This description explains all observed characteristics of the spurious energy on the geophones. This noise, hereafter referred to as "V(z) noise", often is so severe that without adequate tools for removal, the advantages of dual-component ocean bottom acquisition are practically negated.