Estimation of CO2 Storage Capacity in South Part of Iran

Abstract

Iran, with a record of over one century of oil production, is currently one of the major oil producing countries of the world. Several of the old fields have been depleted to an uneconomical level of production which requires significant amount of natural gas for re-injection so that currently over 100 million cubic meters of natural gas is re-injected daily to maintain or enhance oil production to an economical level. It is estimated that in order to maintain oil production, over 200 million cubic meters of natural gas will be needed daily by 2015. However, due to the increased level of domestic and export demands for natural gas, IOR, EOR with natural gas is prohibitive and therefore portions of this amount of natural gas can be substituted by carbon dioxide. In the other hand, CO2 emission increased from 240 MM ton per year in 1994 to 382 MM Ton in 2006 which 40% of this emission is related with stationary sources like power plants and industries. According to the fact that part of CO2 can be remain in reservoir in IOR/EOR projects. The CO2 storage capacity was studied for IOR/EOR project in Iran. 20 main mature oil fields were considered and so many factors same as reservoir pressure, temperature, depth, geological condition, exist faults, crude density, crude viscosity and crude composition were considered at first step. Then suitable reservoirs have been chosen. In the case of Oil and gas reservoirs, the fundamental assumption is that the volume previously occupied by the produced hydrocarbon becomes, by and large, available for CO2 storage. Consistent with the resource- reserves pyramid concept, both theoretical and effective CO2 storage capacities are calculated according to formation volume factor, reservoir area, thickness, porosity and water saturation. Water saturation changes that can affect storage capacity, was simulated by formula obtained from laboratory test in carbonated reservoir and according to oil displacement. Conclusion illustrates that more than 16 Giga ton CO2 equivalent 20 years current annual emission of Iran power plants, can be stored in selected reservoir in south of Iran.