Discrepancies in terms of hydrocarbon initially in place volumes (HIIP) between static and dynamic models might take place because of nonlinear dependency of the saturation height function (SHF) versus porosity and averaging of height above free water level. Upscaling tends to eliminate the high and low porosity values in favor of the average porosity, which might lead to substantial changes in the resulting water saturation. Furthermore, pressure and compositional variation with depth in the dynamic model might lead to substantial contribution to the discrepancies, independent of upscaling.
We present a procedure to address the above issues and provide full consistency between static and dynamic models in terms of HIIP, without the use of capillary pressure (Pc) scaling by the reservoir simulator. A "preprocessing" workflow is used to slightly reassign the Pc curve of each grid block so that a very close match is obtained between the two models in terms of HIIP.
Results show that HIIP obtained from the dynamic model through equilibration using the proposed procedure are within 1% of those obtained using the static model without having to use Pc scaling in the reservoir simulator which warranties realistic and physically valid Pc curves in the reservoir dynamic model initialization process.