The benchmark primary drainage Saturation Height Function (SHF) is a standardized dimensionless function that describes the expected saturation-depth profile for a specific rock type resulting from primary drainage. The paper's ambitious goal is to introduce the concept of creating an inventory of benchmark functions for every reservoir rock type. The benchmark function is the reference point to validate the fluid fill history and identify areas of primary drainage for a specific field. Furthermore, it can be used as a diagnostic tool to analyse changes in the reservoir rock type and pinpoint fluid fill variations. The benchmark function is a complementary model to constrain the SHF when there are insufficient data, especially in the transition zone. A key diagnostic criterion for a reservoir rock type is that it contains a consistent combination of pore types and hence has consistent (or predictable) capillary properties. Case studies on carbonate fields are presented from the Sultanate of Oman. The same concept is also applicable to clastic reservoirs. The benchmark primary drainage function can be derived from the capillary pressure data. Conversion of this data into a normalized capillary pressure system is required. In this paper, we will introduce a workflow to utilize the saturation log data from different fields to build a benchmark function that is not influenced by reservoir fluids densities' and interfacial tension. Benchmark primary drainage functions were created in different scenarios and rock types to aid saturation modelling in several fields. In one carbonate field, the saturation log data from an analogue field were used to constrain the transition zone due to data limitations. The benchmark function was also used to identify fluid fill variations and unlock a potential development. The benchmark function of micro-porous rock, derived from several analogue fields, was the baseline for the saturation modelling workflow of a complex carbonate reservoir with a tilted contact and significant imbibition and it was a vital enabler in simplifying the saturation model.

The benchmark primary drainage Saturation Height Function (SHF) is a standardized dimensionless function that describes the expected saturation-depth profile for a specific rock type resulting from primary drainage. The paper's ambitious goal is to introduce the concept of creating an inventory of...