Petroleum Systems Dynamics of the South Caspian Basin

Stephan J. Duppenbecker
Azerbaijan BU Petroleum Systems Analyst, Middlesex, United Kingdom

The South Caspian Basin represents an extremely young petroleum system in which over 8 kilometres of sediment have been deposited in the past 6-10 million years with up to 3 kilometres in the last 1-2 million years. The high deposition rates have pushed the sedimentary section into significant disequilibrium with respect to temperature and pore pressure evolution. The basin dynamics are expressed in: (1) rapid, vertical and lateral pressure changes that challenge the capacity of seals to build and preserve petroleum columns and (2) in low temperature gradients which delay petroleum generation and reservoir diagenetic processes. Basin Modelling has proven to be the key technology in understanding the South Caspian Basin dynamics and quantifying their impact on petroleum generation, migration and seal capacity evolution, as well as in assessing prospect drillability and field development options.

The Miocene Maykop Source Rock series is overlain by a group of world class reservoir systems and extensive lacustrine shales which are folded into extremely large anticlines. Depending on the regional extent of the sandstone “sheets” high pressure is transferred both regionally from the overpressured basin to the basin margins, and semi-regionally from syncline to crest, and this results in reduced seal capacity for petroleum accumulations and stacked pays. This complex regional aquifer pressure distribution can explain variations in fluid contacts observed in structures along the Absheron ridge. The resultant low effective stress in the shallow section also creates substantial drilling and field development challenges.

The complex interaction between the 3D connectivity of high permeability sediments (aquifers) and the 3D architecture of the low permeability sediments (aquitards) can be best understood using integrated basin modeling simulation techniques.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas