Perpustakaan Digital ITB

Deliverability calculation in gas condensate reservoir has a uniqueness compared to other reservoir types. During its production period, the condensate starts to arise as the pressure falls below the dew point pressure. The amount of condensate increases as the pressure decreases, but in certain value of pressure, condensate rate decreases to a point where no condensate forms anymore, in which the phenomenon is widely known as retrograde. In this study, the phase diagram construction algorithm is developed to show retrograde phenomenon. To estimate the deliverability which shows retrograde phenomenon, flash calculation is expected to approach the suitable solution. This study involves the application of pseudo-compositional method, in which the fluid physical properties are calculated on the basis of phase fraction in a system. The reservoir is assumed in pseudo steady state flow (PSS) condition in order to represent the entire reservoir condition. The basic algorithm lies on iteration process; time processing and the precision of solution must be considered. Initially, it is required to use Newton-Raphson iteration method. This method yields the solution rapidly, but somehow in several conditions the solution cannot be found. Thus, the bisection method is used afterwards as it always yields the solution since there are two limits in calculation. The combination of these methods; Newton-Raphson and bisection, could precisely estimate gas condensate reservoir deliverability and reduce processing time.