Performance Analysis And Prediction Of Songo Songo Gas Reservoir

In recent years,huge amounts of natural gas have been discovered in Tanzania.The discovery of Songo Songo gas reservoir marks the first class natural gas discovery over the East Africa region and concludes that every potential hydrocarbon basin across East Africa is the subject of intensive interest.Songo Songo gas reservoir has pronounced a big impact to the economy of Tanzania,which contain huge amount of natural gas.This study aims to give a better understanding of the performance of gas reservoir,predict the future production,and help to decide the future adjustment plan for gas production in this reservoir.Decline curves analysis and numerical reservoir simulation are important reservoir engineering tools used to predict the reservoir performance and recovery factor.The decline curve analysis,including Arps decline curve and Fetkovich type curve,are applied to study the trend of the gas production with time.During the wells production analysis,hyperbolic decline behavior is observed at different stages of production,therefore binomial series expansion together with linear regression method are used to obtain the hyperbolic decline constant,then the Arps decline equation is used to predict future production rate and cumulative gas production for the next 15 years.To study the variation of gas production in the real heterogeneous reservoir,the numerical reservoir simulations are run.History match is performed to obtain the adjusted simulation model,which is then used to predict the future reservoir performance.At last,the sensitivity studies are done to study to the impact of reservoir permeability,effective thickness,well space and bottom hole pressure on the gas production.The decline curve analysis shows that most of the wells exhibit hyperbolic decline characteristics.The decline exponent varies from 0.15 to 0.4.After 15 years of production,the reservoir production rate will decrease from 7.315 MMscf/day to 2.12 MMscf/day,and the gas recovery factor will be 72%.The gas production rate and gas recovery factor obtained from reservoir simulation are lower than those from decline curve analysis.The reservoir simulation results show that the cumulative gas production from Songo Songo reservoir will be 4984.702 MMscf and the recovery factor will be 77.6%.Sensitivity studies indicate that the gas flow rate is most impacted by bottom hole pressure changes,reservoir simulation followed by well space and net pay thickness.Since the gas production rate declines fast in Songo Songo gas reservoir,the increased oil recovery methods should be designed and implemented as soon as possible.