This thesis explores whether vertical stratigraphic cross flow from the A zone to the C1 zone of the Upper Slochteren Member can occur without wellbore crossflow, and under what conditions such recharge is plausible. The study focuses on the B-well in the L-field, Dutch offshore North Sea, where production resumed after a shut-in period, and pressure behavior suggested possible recharge. Four different basecase models were constructed using Rapid Reservoir Modeling (RRM), each representing a different degree of vertical connectivity across the B zone. These models were then transferred to Computer Modeling Group (CMG) software, where dynamic multiphase simulations were performed to assess gas flow between the zones of the Upper Slochteren Member.
The results show that stratigraphic recharge from A to C1 is possible, but highly sensitive to the inter- nal architecture of the B zone. Increased vertical connectivity across the B zone consistently show earlier pressure communication and higher gas fluxes into the C1 zone. Sensitivity analyses were conducted on porosity, vertical permeability, and gas relative permeability to test their influence on flow behavior. These parameters affected not only the rate of gas migration, but also the degree of pressure redistribution across the model, which influences the gas rates even further. Capillary pressure and water saturation were also found to control gas mobility, particularly in low-permeability or heterolithic intervals. The findings do not fully support the hypothesis that stratigraphic recharge explains the observed pressure response in the reservoir, but suggest it may account for part of it. Additionally, the results emphasize the importance of considering vertical heterogeneity and capillary forces when evaluating near-wellbore connectivity.