Multiple Identification in Surface Seismic Data through VSP Multiple Analyses: A Case Study

Both surface and interbed-generated multiples are an integral part of surface seismic datasets, and several techniques are used to identify and remove them. Unfortunately, there is not a single technique that can accurately identify and remove every multiple in a dataset, so interpreters often work with datasets that contain several multiples. A vertical seismic profile (VSP) has a unique geometry in that the receivers are in the subsurface and can, therefore, record both a down-going and up-going wave field. The down-going wave field is used for deterministic deconvolution and can successfully identify and remove all multiples. The resultant corridor stack is multiple free and can then be compared to the surface seismic. Several techniques can then be used to identify any residual multiples in the surface seismic data, including information about the origin. This paper presents a case study to identify multiples in the surface seismic data of a field in the Asia Pacific region. The paper will show how the VSP data is processed to produce a corridor stack that is multiple free, a corridor stack that contains both primaries and multiples, and a stack that contains only multiples. These are then merged with the surface seismic data to accurately identify any residual multiples. The residual multiples can then be removed through further processing