Saturations Calculations Using Saturation-Height Modeling on the Well Mariana, offshore Lower Congo Basin - Saturation Height approachs

Abstract

Saturations calculations have been, for many years, object of high importance for the oil industry. Many literatures show different empirical and scientific efforts to produce robust saturations functions which attempt to address almost all properties of the rocks and fluid interaction. These features are mostly porosity, resistivity and factors that address the type and particularities of the formation. Saturation Height (SwH) functions may address all these properties, including permeability, but relies on the variation of saturation as function of the Height Above the Free Water Level (HAFWL) or capillary pressure. Mapping of water saturation away from the wellbore in for instance geo-models is the main purpose of saturation height modeling. Saturations height functions are important as can highly influence the STOIIP or GIIP calculations for a reservoir and enhance the perforation depth decision. Many methods for SwH functions are available in the literature. The purpose of this thesis relies on the application of some of these methods to a given field and to discuss conformity and disparity with the saturation model already applied to the field. For that were used and processed in the software Geolog raw log data of a well, Mariana, drilled within the Lower Congo Basin Ultra-deep-water province, offshore of Angola. Two saturation-height models equation were applied to the well Mariana to compute water saturations which showed to give reliable results, FOIL method (Cuddy) and Leverett (J) Function. Both methods showed to be reasonable for the Saturations calculation of the Well. Cuddy Method revealed to overestimate, whilst Leverett (J) showed to underestimate the saturations results, when compared to the Saturation reference used previously in the well.