Simulation of Underground Natural Gas Storage in Sarajeh Gas Field, Iran

Abstract

Abstract One of the main concerns in Tehran during winter is the pressure drop in gas transfer lines which leads to shortage in gas supply to the northern part of the city located in higher altitude. To deal with this problem, National Iranian Gas Company (NIGC) decided to store gas in nearby natural reservoirs during hot season and produce it during cold season. Sarajeh gas condensate reservoir, located 145 Km far from Tehran, was considered for underground gas storage (UGS) to deal with gas demand in Tehran. First, the significance of UGS, different types of reservoirs considered for UGS and its history are presented; next, coarse grid model of the reservoir is built; simulation and history matching of Sarajeh gas field are introduced and briefly discussed and finally conclusions and recommendation for future work is presented. Based on available information and those generated by the model, this field could be a candidate for UGS plan. The results showed that two horizontal and one vertical gas production wells need to be drilled to achieve pressure drop in the reservoir and deliver 150 MMSCF of gas per day including production from existing three gas producers. Reservoir performance after history matching using depletion scenarios is predicted and depletion last for 4.5 years. Ultimate recovery factor is 65% for gas and 40% for gas condensate. Following reservoir depletion to approximately 2400 Psi, gas injection cycles in 6 months during hot season with the injection rate of 160 MMSCF per day and gas production cycles in 5 months in cold season with the rate of 175 MMS per day can start. Total gas volume stored in each cycles is approximately 1 × 1012m3.