3D De-multiple over Shtokman–A Case Study

In this case study we discuss parameterisation considerations for General Surface Multiple Prediction of complex 3D multiples on the Shtokman field in the Russian sector of the Barents Sea. The multiples in this area are very complex even though the water bottom is fairly simple. Nevertheless small irregularities in the sea bed create some multiple diffractions. Because of their 3D nature, it is not possible to predict and remove multiple diffractions using 2D de-multiple techniques as the multiple ray-paths lie outside the plane of acquisition in the sail-line direction. The multiple prediction was performed using a new approach to 3D SRME ‘3D General Surface Multiple Prediction’ (3DGSMP) described by Moore and Dragoset (2008). This enabled up to generate a more accurate multiple model which helped attenuating the multiples much better than what we had seen with 2D assumptions. In this paper we will firstly present the Shtokman field, we will then discuss why the 2D SRME approach has not managed to attenuate very effectively the multiples and follow with a discussion on the parameterisation of the 3D GSMP for the multiple prediction where we compare 3D GSMP with 2D SRME.