Abnormally-high formation pressures in Azerbaijan and the South Caspian Basin (as related to smectite ↔ illite transformations during diagenesis and catagenesis)

The present paper highlights the problems related to the abnormally-high formation pressures (AHFP) in the oil and gas fields of Azerbaijan and the South Caspian Basin. The authors discuss the origin of abnormally-high formation pressure, diagenetic-catagenetic montmorillonite-illite transformation and hydrochemical factors. On the basis of new data, the sealing properties of argillaceous rocks (caprocks) and oil and gas potential of the reservoir rocks at great depths are also discussed.