Imaging to eliminate water-bottom multiples

Lin Zhang

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ABSTRACT

On a common midpoint (CMP) gather, the water-bottom multiples are characterized by their moveout of small stacking velocities. In this paper I describe a new velocity discrimination method to eliminate these low velocity events. The new method is similar in principle to the velocity filtering method. First the CMP gather is transformed into a distorted image by using a velocity-dependent operator. The velocity of the operator is chosen in such a way that the distorted images of the water-bottom multiples are separable from the distorted images of other events. Eliminating the images of the water-bottom multiples is followed by the backward transformation, to give a CMP gather free of the interference of the water-bottom multiples. The synthetic example and field-data example show that the algorithm works to a certain extent; however, several problems remain to be solved.