https://petroleumjournals.online/journals/index.php/petrophysics e-journal of petrophysics is a peer reviewed, open access journal published by Petroleum Journals Online Petroleum Journals Online en-US e-journal of petrophysics 1712-7866 <p>Copyright for articles published in this journal is retained by the authors, with first publication rights granted to the journal. By virtue of their appearance in this open access journal, articles are free to use, with proper attribution, in educational and other non-commercial settings. <a href="http://creativecommons.org/licenses/by-nc-nd/2.0/">Click here for further details.</a></p> https://petroleumjournals.online/journals/index.php/petrophysics/article/view/15 Calculation of initial fluid saturations is a critical step in any 3D reservoir modeling studies. The initial water saturation (Swi) distribution will dictate the original oil in place (STOIP) estimation and will influence the subsequent steps in dynamic modeling (history match and predictions). Complex carbonate reservoirs always represent a quit a challenge to geologist and reservoir engineers to calculate the initial water saturation with limited or no SCAL data available. The proposed method in this study combines core data (permeability) from 32 cored wells with identifiable reservoir rock types (RRTs) and log data (porosity and Swi) to develop drainage log-derived capillary pressure (Pc) based on rock quality index (RQI) and then calculate J-function for each RRT which was used to calculate the initial water saturation in the reservoir. The initialization results of the dynamic model indicate good Swi profile match between the calculated Swi and the log-Swi for 70 wells across the field. The calculation of STOIP indicates a good agreement (within 3% difference) between the geological 3D model (31 million cells fine scale) and the upscaled dynamic model (1 million cells). The proposed method can be used in any heterogeneous media to calculate initial fluid saturations. Tawfiq A Obeida Yousef S Al-Mehairi Karri Suryanarayana Copyright (c) 2005-08-13 2005-08-13 1 1