ABSTRACT
Understanding of reservoir fluid properties especially density and viscosity is very relevant for field development. Reservoir water is highly saline resulting in higher water density. These reservoirs may contain the following types of natural reservoir energy that controls the reservoir performance: rock-fluid expansion; solution gas or depletion drive; gas-cap drive; water drive; gravity segregation drive; and combination drive. An undersaturated black oil reservoir with initial reservoir pressure higher than bubble-point pressure away from critical point may produce oil at isothermal condition due to liquid and rock expansion. Gas-cap reservoirs contain a free gas at the upper portion of reservoirs with little or no water at the lower portion of reservoirs. Water-drive reservoirs are more efficient in terms of recovery. They are associated with aquifer present in the lower part of reservoirs. Reservoirs generally contain combination of energy sources and drive mechanisms.
