Qualitative Interpretation of Astokh Time-Lapse Seismic Results

The first Time-Lapse survey in Russia was shot in 2010 at Astokhskoe oilfield, operated by Sakhalin Energy Investment Company. The Astokh field is producing from several reservoirs with different reservoir quality and complex internal architecture. 10 Years of production from the good quality reservoir left a clear imprint on 4D seismic results. The different seismic processing was implemented on base and monitor surveys. Firstly pre-stack time migration was done, which was followed by pre-stack depth migration. The topic of this paper is qualitative interpretation of the 4D results. It includes analysis of attributes based on Base/Monitor cubes, Difference cube and Timeshift cube. All data sets are inspected after PSTM and PSDM processing. The PSDM data were analyzed not only for the full stack, but for 4 angle range stacks as well.