Analysis of Use of Low Quality Natural Gas to Improve Oil Recovery Factor

Analysis of Use of Low Quality Natural Gas to Improve Oil Recovery Factor Authors: S. Nagy, A. Olajossy  Enhanced oil recovery methods are applied more frequently nowadays, mainly because of economic reasons. The classic water fl ooding methods that aim to maintain the reservoir pressure are substituted or updated by the Water Alternating Gas (WAG) Technology. It involves alternating injection of water and gas, or simultaneous injection of water into the bottom of reservoir and gas into the cap of it. The application of high-nitrogen content gas, residue gases after methane-nitrogen separation processes, carbon dioxide or solutions containing carbon dioxide and nitrogen are considered in terms of the oil recovery effi ciency, defi ned as obtaining of a maximal depletion during twenty years of exploitation. For the selected small oil reservoir in the Polish Lowland, it was performed model research with usage of a pseudo-compositional simulator. Various aspects of gas injection concerning increasing of the reservoir pressure were analyzed, particularly those involving injection into the cap through two wells as well as through four ones. Performed calculations are presented in this paper. The best results were obtained for the injection of the pure carbon dioxide. Other satisfactory solution involves injection of carbon dioxide through two years, and after that injection of nitrogen or the mixture of carbon dioxide and nitrogen. The presented results are promising and show potential possibilities of rising oil recovery by 50-80% with reference to the case without gas injection.

 

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