Abstract: Organic facies and petroleum potential of the Oligocene- Lower Miocene source rocks from Crimea to Azerbaijan

SAINT-GERMES, MARIA, FRANCOIS BAUDIN, OLGA BAZHENOVA and NATALIA FADEEVA

The Maykop Series are composed of terrigeneous marine sediments deposited during Oligocene and Lower Miocene in one of the Eastern Paratethys basins. Their thickness reaches 3000 m in the type area, where monotonous shaly facies are dominant, whereas thin sandy facies (100 m) occurs in proximal domain(s). This series is one of the effective source rocks of oil and gas in Crimea, Precaucasus and Azerbaijan.

The study of the organic content of 800 samples from outcrops and wells have been performed in order to understand changes in the carbon sources with respect to the paleogeography, paleoclimate and morphology of basins. Investigations include determination of organic carbon content (Leco), Rock-eval pyrolysis, bitumen composition of chloroform extracts, gas-liquid chromatography, carbonate determination, measurement of the different forms of both Fe and S, as well as palynological observations.

Most of the studied samples contain between 1 and 4% TOC and some levels reach 16%. The hydrogen index values of immature samples indicate a mixture of type II and III organic matter or an altered type II. The levels with high TOC show a type II organic matter. Nevertheless, petroleum potential is medium (2-7 kgHC/t). Palynological analyses show that the Maykop claystones contain mainly amorphous organic matter, associated with both terrestrial (pollen, spores, small wood fragments) and marine (dinocyst, algal, foram linings) particles. Some medium HI values, associated with the dominance of amorphous organic matter, are thought to be related to a consumption by sulfate-bacteria during early diagenesis.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria