Generally speaking, Gas Condensate Reservoirs may refer to those reservoirs that are producing fluid with the oil gravity of higher than 45°API and the gas-oil ratios of between 5,000 to 100,000 scf/bbl. These types of reservoirs are often found in the deep wells (below 10,000 ft), and the gas that condenses to liquid at the surface temperature and pressure is light color or colorless. Sometimes gas-condensate is called wet gas; the term "wet" does not necessarily mean that gas contains water, it refers to heavier hydrocarbons in the gas mixture.

Table 1. shows the comparison of gas-condesate compositions with the dry gas compositions; as it is seen in this table, the percentage of heptanesplus in gas-condensate fluid is greater than it is in dry gas fluid. This results in higher gas-oil ratio for dry gas fluid at the surface.

In order to understand the behavior of Gas-Condensate Reservoir, the PT phase diagram is presented in Figure 1.

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