The contact surfaces in reservoir segregating fluids with different densities (normally between gas, oil and water) formed by gravity and capillary pressure.
Free Water Level (FWL) | |
HC-Water Transition | This interval is characterised by commingled hydrocarbon and water production from the same reservoir. The height of the interval may vary from dozens of meters to fraction of a meter depending on capillary pressure. |
Fig. 1. Fluid contact schematic: gas in yellow, oil in green, hydrocarbon-water transition in blue and free water in aqua. |
Usually the fluid contacts are relatively flat but varying reservoir properties may lead to inclination of the contact surface.
The exact knowledge of fluids contact is critical in reserves estimation.