Perpustakaan Digital ITB

Over years, water saturation height function has been studied and investigated. Leverett initiated the discovery by studying the effect of capillary pressure and water saturation in a reservoir model. However, as the equation are mostly derived empirical, there is no one model that fits all the field cases. This paper will present the result of vertical initial water saturation models that are based on proposed equation that derived from Archie, Leverett, and Brooks-Corey. This approach is started with the analysis of conventional well logging that honors gamma ray, resistivity, neutron, and density log to provide the basic calculation of shale volume, porosity, and water saturation along the depth of the well. Log data analysis that is integrated with drill stem test, RFT/MDT, and PVT Test also provide the analysis of fluid properties, facies, and reservoir zone. Then MICP from SCAL data are processed to provide the relation between capillary pressure and water saturation in each core sample and construct the J-Function. Finally, J-Function log-based is established using proposed method and matching procedure with J-Function core-based are done through curve fitting. Two field cases of gas wells in carbonate reservoir are brought to be investigated. Through the procedure, the result of J-Function log-based agreement to J-Function core-based is good. Then saturation height function is also built using proposed method. The result is compared with another method of saturation height function, which are Johnson, Woody-Wright, Sondena, Alger (Cap-Log), Cuddy, and Skelt-Harrison. The proposed method yields the lowest mean square error confirming the result of water saturation derived from Archie resistivity log. This method also provides better understanding of petrophysical rock type. Through this investigation, this method is capable of model the petrophysical rock type and saturation height function using log-derived based. The analysis of uncored zone is also covered, as every well mostly has itself being logged but not cored. This method also covered the complexity of predicting the permeability, especially in carbonate reservoir, as permeability is not used along the procedure.