PETROLEUM GEOLOGY AND EXPLORATION PROSPECTS IN THE SOUTHEAST OF PRE-CASPIAN BASIN OF KAZAKHSTAN

During the evolution of the Pre-Caspian Basin from the marine Paleozoic to the terrestrial Jurassic-Cretaceous, there formed three hydrocarbon plays, i.e. the pre-salt, salt and post-salt depositional groups. The pre-salt group is deeply buried. Most of the large oil and gas fields of this group discovered so far occur in the carbonate deposits along the margin of the basin.Both the post-salt and salt depositional groups consist of clastic deposits. The salt group is characterized by the occurrence of large oil and gas field within a depth of 1 800-4 000 m, and the oil are of high quality. The post-salt group contains a great number of hydrocarbon reservoirs, of which all are small in scale, shallow in depth and thick in oil viscosity.As far as the exploration potential is considered, the salt group is better than the post-salt group. Most of the exploration targets are distributed in the basins between salt domes. It is believed that the pre-salt group is favorable to the formation of medium and large oil-gas fields, and should be highly considered as an exploration target.