Shallow water multichannel sub-bottom profiling using Kirchhoff imaging

Abstract

Single-channel sub-bottom profilers are commonly used for shallow water seismic investigation. This work reports the design and construction of a multiple channel profiler that allows more effective seismic imaging techniques. The system is composed of a controlled acoustic source and a 1.6 m long array with eight evenly spaced receiver channels, and operates using CHIRP signals with frequency ranging from 800 Hz to 8 kHz. A survey was carried out to obtain seismic data in the region of Lagoa da Conceição, Santa Catarina, Brazil. The acquired data was processed using a seismic imaging technique based on the pre-stack Kirchhoff time migration. Both the multichannel seismic data acquisition system and the applied imaging technique showed to be robust for acquiring subsurface information. The use of the pre-stack Kirchhoff time migration resulted in a seismic image with reflection events allocated in the real position and without bow-tie effects since it repositions the diffracted energy back to the spreaders that originated it. This procedure results in a more reliable subsurface image of the studied environment, when compared with single-channel sub-bottom profilers.