Pore Pressure Prediction in the Caspian and Kazakhstan Regions; Taking a Geological Approach

Abstract

The Great Caspian is a leading, prolific producer of hydrocarbons; this region consists of the North, Middle and South Caspian. A major issue in exploiting these hydrocarbons is an understanding the varying pressure regimes therein, that are a direct result of the interaction between tectonics, lithology (e.g. salt, carbonates) and rates of sedimentation. Accurate pore pressure prediction is vital for successful and safe drilling in order to exploit these accumulations. We state that a geological approach is vital to supplement the other numerous methods for pore pressure prediction used worldwide and applied commonly in this region. These other methods often rely on shale-dominant lithologies – therefore, in this region using standard shale interpretations will be inaccurate. For instance, In the North Caspian, the Tengiz Field is located under less than 500 feet of Permian salt; above the salt the sediments are hydrostatic, below the Carboniferous carbonate reservoirs are close to lithostatic pressures; in these cases, traditional low temperature shale analysis will give only a partial solution at best. In the South Caspian, reservoirs may be up to 5000 psi naturally drawn-down relative to the shales in fields such as Shah-Deniz via lateral drainage