Abstract:

The Pre-Caspian basin is one of the largest oil and gas bearing basins in the world, and the Carboniferous Carbonate reservoirs in the eastern margin are favorable hydrocarbon reservoirs. Based on study of main diagenesises and controlling factors of Carboniferous carbonate reservoirs of  Kenjiyak and the central block of Zananor oil field, the paper showed that the dorag dolomitization is one of the most important and common genetic types of dolomite, and dolomite formed by dorag dolomitization is the most favorable reservoir. Dolomitization is closely related to the sedimentary environment,  and to some degree, the distribution of dolomite may be regarded as an indicator for microfacies. The mobility of the pore water is different in each depositional environment and facies zone, so diagenesis has different influence on the development and evolution of porosity in each facies zone. Sedimentation is the determinative factor which affects the quality of reservoir and different diagenesises is in connection with the distribution of sedimentary microfacies. The closer to the Carboniferous unconformity surface, the more  favorable diagenesis and tectonizations will take place.  As a result,  the upper Carboniferous carbonate reservoir of the margin of the Pre-Caspian basin is the most promising hydrocarbon reservoir and it is expected to find more oil and gas reserves there.

Key words: dolomization, diagenesis, controlling factor, Pre-Caspian basin