Pinch–out Prediction using Seismic Facies Analysis

Determination of the most reliable formation pinch-out position is extremely important since it has influence on calculated STOIIP and development efficiency. Western-Siberian Oilfield X is under development stage at the moment. Territory is covered by 3D seismic, more then 100 wells was drilled. Productive interval overlies the basement pinching out on its highs. Furthermore, formation is affected by secondary carbonatiozation. These geological features negatively influence on determination of the pinch-out contour. Choice of techniques was done based on knowledge about formation acoustic model. Tested standard approach concerned with amplitude analysis didn’t show any positive results. Based on generation of synthetic wedge model, main seismic characteristics of pinch-out zones were identified. Then waveshape as attribute including all defined wavefield features was chosen. To provide generation of a seismic facies map it was decided to use supervised classification based on neural network technology. Seismic traces at locations of real wells were used as input data. The pinch out boundary was created by contouring of the seismic class corresponding to a well in formation absence zones. As a result, the most probable case of the formation pinch-out contour was identified. It is more optimistic related to another one created using standard amplitude methods