Typical saturation height modeling assumes that the migrated hydrocarbon has displaced water under primary drainage until pressure equilibrium controlled by buoyancy, pore throat size, and the position of the free water level (FWL) is reached. When leakage of the caprock or a structural tilting after migration occurs, a shallower position of the new FWL involves an imbibition cycle to represent the initial saturation distribution in a 3D reservoir model.
The methodology starts at the well level by building drainage saturation height functions (SHFs) typically from core capillary pressures (
A synthetic case, of tilting after migration is used to illustrate the methodology. The rock typing scheme and the petrophysical properties from logs are coupled with the saturation height modeling defined from
Methodologies to build 3D saturation height models in drainage consistent with reservoir rock types are common practices. The equations for modeling water saturation by including an imbibition cycle have also already been defined. The developed workflow combines both methodologies to initialize a 3D static saturation model that honors the fluid fill history associated with imbibition and is consistent with petrophysical properties of the reservoirs. The method has been fully coded into commercial software and can be readily implemented to real case studies.