Published May 2012

Isotopic-geochemical models of reservoirs infill of South-Caspian basin productive series

D.A. Huseynov

The paper deals with issues of application of the important geochemical parameters of oils for reservoirs infill mechanisms reconstructions and revealing the trends of fluids migration within the South-Caspian basin. The model geochemical constructions have been conducted in fields Guneshly, Garadagh, Kurovdagh, Garabaghly and Neftchala. It had been shown that isotopic composition and maturity of basin oils are in the direct dependence upon the history of its tectonic evolution, caused the multiphase migration of fluids and traps infill. In Guneshly field the reservoirs of Productive Series (PS1) filled earlier, then PS2. At the same time in PS2 the infill of Pereriv Suite reservoirs took place more intensive and longer than in horizons IX and X. The late portions of vertical migration fluids drove away the less mature oils in the north-eastern and south-western directions. The intensive downwarping of South-Caspian basin in the Upper Pliocene Quaternary time along the bounding deep faults was the main reason of continuity breach of the Paleogene- Lower Miocene fluid-conduits, along which the regional lateral migration of fluids took place from the central part of Jeyrankechmez - South-Absheron depression towards its flanks in direction of Gobustan, Absheron peninsula, northern uplifts of Baku archipelago and Absheron sill. As a result the formed deposits turned out to be isolated from the feeding Paleogene Lower Miocene source. The second phase of migration is associated with Middle-Upper Miocene (Diatom) deposits entry into the oil generation zone. Reservoirs of fields of Kurovdagh-Garabaghly-Neftchala anticlinal zone infilled at the expense of primary migration of fluids from local sources located within the Mughan-Salyan depression.