Feasibility study of the Songo Songo gas field capacity increasing in terms of wells heads pressures behaving trend
MetadataVis full innførsel
Pressure behaving trends for the gas wells is one of the importance subjects that have to be known for the confidence production fore casting expectations. Once the pressure demand will not be in the ranges that can allow gas to reach the intended customer, there is a need of analyze when that happens and what measures has to be taken in order to return the operating pressure into their normal routine. Normally gas compression is done in order to boost gas pressure and hence returns into the normal intended operating conditions.The purpose of this thesis was to analyze how feasible the process of increasing gas capacity in Songo Songo gas field, from currently 101 MMscft/d to 200 MMscft/d will be, in terms of the gas transportation pressure. The plan of gas capacity increasing was early planned to start in 2015 year. The field currently contains seven production wells, SS-3, SS-4, SS-5, SS-7, SS-9, SS-10 and SS-11. Among those wells only SS-4, SS-7, SS-10 and SS-11 are the currently operating wells. The remaining wells were closed because of the corrosion problems PanAfrican Energy Tanzania (2011). In order to meet 200 MMscft/d target, Management decided to re-work over the closed wells, drilling a new well, SS-12 and adding another gas processing train.In order to have precise prediction, field history matching which specifically involves only wells heads pressure matching from the starting of field production (24/06/2004) up to 30/12/2008 were conducted. The process of reservoir performance prediction in order to make history match with the existing well heads production data was done by means of IMEX/ CMG Simulation package. Wells which were involved in the history matching process are SS-3, SS-4, SS-5, SS-7 and SS-9. These are the only wells which were present during the specified interval of history matching. The chosen reservoir grid blocks tuning factor for the process was permeability. Several grid blocks permeability s multiplication factors were used. The only permeability multiplication factor that provides satisfactory well heads pressure matching was 1.5.IMEX / CMG Simulation package was again used after history matching process for the purpose of reservoir prediction performance analysis form 24/06/2004 to 30/12/2025. From the simulation, flowing bottom hole pressure of each well was determined at each time step and further used for the calculation of the well head pressure estimation. The minimum plants wells heads pressures requirements used, in order to allow gas transportation to customers were (1526 psig).Upon the results, it had observed that the field gas production rate of 200 MMScft/d will not be maintained until 2025, it will start to decline early on 02/02/2022. Also none of the wells will deliver pressure higher or with the same value as the minimum plant requirement until the end of the study. This effect then leads the need of compressor installation before the end of the field production (30/12/2025).