Prestack Inversion and Probabilistic Lithofluid Classification - A Case Study from the Caspian Sea

The Caspian Sea is currently one of the focus areas for exploration and production in the FSU. Logistically a challenge (large areas with very shallow water) and ecologically sensitive (endemic flora and fauna), it demands operators to develop a sustainable approach to hydrocarbon development in the region. In that context, a better understanding of the subsurface helps to optimize drilling activity as one of the factors having a huge environmental impact. The AVO inversion and probabilistic lithofluid classification approach presented in the current paper, is one of the technologies applied to improve the subsurface understanding of the area in order to optimize the future field development. The workflow includes seismic data improvement by reservoir oriented processing procedures, a comprehensive rock physics analysis on well data, simultaneous inversion of angle stacks, crossplot analysis of inversion results and probabilistic lithofacies classification in the AI-Vp/Vs domain using the established depth dependent rock physics trend. First experience of using a probabilistic approach to quantify the reservoir properties shows that potentially even pore fluids can be estimated from seismic data.