An alternative to Geolog software for fast calculation of water saturation using borehole data in a shaly sand reservoir, case study, Ahwaz Oil Field

Water saturation evaluation has a direct effect on estimating hydrocarbon reserves in reservoirs, and inaccuracy in its values would affect the economics of field management and development plans. in shaly reservoirs it is a difficult task due to heterogeneity nature of shale and the way the shale distributed in reservoirs. So many scientists proposed models to determine water saturation from well logs in shaly sandstone reservoirs. The scope of this petrophysical study is to use five most commonly applied water saturation models (Archie’s equation, Indonesian model, Simandoux, Fertl model, Schlumberger model) to estimate water saturation. Comparative analysis of water saturation calculated from the models and Geolog software was carried out with the aim to determine the most suitable water saturation model, alternative to Geolog software for fast calculation of water saturation in the studied area. The results show that the Fertl model is more consistent with the output of Geolog software and is able to predict water saturation with the least error compared to other methods. This work also clearly shows that the water saturation value was strongly sensitive for input parameter in low porosity and low log resistivity zone.

کلیدواژه ها:

shaly sandstone reservoir ، petrophysical properties ، middle-east ، Water saturation ، log analysis