Perpustakaan Digital ITB

Production optimization of geothermal wells can be done if subsurface characteristics such as location and flow contribution of fracture zones, PI, and deliverability are well-known. One way to determine those subsurface characteristics is by doing PTS testing to the well and wellbore modeling. The modeling calculates pressure drop in wellbore by involving momentum balance, energy balance, and mass balance equations for both single-phase and two-phase flow. For two-phase flow, there has been no single pressure drop correlation that can be compatible to all types of wells under various enthalpy and pressure conditions. Normally, modeling two-phase flow in geothermal wells adopts the theory used in oil/gas which often uses correlation such as Duns-Ros, Hagedorn-Brown, Orkiszewski, etc. As they require a lot of functions and conditions to determine the flow pattern, the pressure drop calculation is quite complicated. This paper investigate another model of two phase flow using void fraction method that is easier in the making process. The model of two-phase flow void fraction method only needs to change one parameter that is the correlation of void fraction to get a model well-suited with observed data. The approach of interphase velocity difference in this correlation is just a function of the fluid properties such as density, viscosity, dryness, etc. The analysis of flow pattern is not required in this model. Author investigate and evaluate the use of seven void fraction correlations with different level of complexity such as Zivi, Chisholm, Lockhart-Martinelli, Premoli, etc. to modeling two-phase wells located in Supreme Energy geothermal field. The results showed that the two-phase model using void fraction Chisholm correlation is the best match to measured data from wells with range of surface enthalpy 880-1013kJ/kg.