Reservoir rocks may have substantially different pore structures in different parts of a field. These heterogeneities may result in significant variations in hydrocarbon-water contacts, especially in low permeability reservoirs ([[:file:fluid-contacts_fig4.png|Figure 4]]). Where all reservoir facies are very porous, heterogeneity of depositional environments does not significantly affect fluid contact elevation. | Reservoir rocks may have substantially different pore structures in different parts of a field. These heterogeneities may result in significant variations in hydrocarbon-water contacts, especially in low permeability reservoirs ([[:file:fluid-contacts_fig4.png|Figure 4]]). Where all reservoir facies are very porous, heterogeneity of depositional environments does not significantly affect fluid contact elevation. |