Modelling of dynamic fluid contacts in chalk reservoirs

These variations are created by a combination of subsidence, structural tilting, migration, capillary pressure conditions and hydrodynamic effects. The relative importance of the different contributions and the dependence on the petrophysical properties are studied: The project combines burial-history, compaction, pressure development, and the resulting temporal change in a reservoir model; with a flow-simulation of the two phases water/oil. The effect of the regional hydrodynamic gradient is incorporated. The geometry of the fluid-contacts is predicted as a function of the temporal development of the reservoir. The significant contribution from this project is the combining of elements from basin-modelling With that of reservoir flow-simulation to study the relative importance of the effects that shape the fluid distribution in chalk reservoirs. The combination of geological modeling and flow-simulation is absolutely necessary for low-permeable chalk reservoirs, because the natural flow of fluids operate at velocities and time-scales that are comparable to the geological effects. The project has shown that the oil/water system in a chalk reservoir needs a very long time-span to equilibrate, and might actually never come to equilibrium, because new dynamic events during the geological history cause renewed non-equilibrium. The modelling method used in the project is capable of reflecting important characteristics in the saturation distribution and fluid contact geometry that are known from reservoir examples