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. |
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| 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 fluid contacts is critical in reserves estimation and field development planning.