问答题 翻译：In general, the thermal capacity of a formation is so large that the reservoir temperature remains essentially unchanged during depletion unless a fluid injection project such as waterflooding or steam injection is initiated.

问答题 翻译：The gas deviation factor can be estimated from well-known correlation charts, using reservoir temperature, pressure, and the molecular composition of the gas.

问答题 翻译：Gas and oil, either as separate fluids or in mixtures, change their state or phase as reservoir pressure changes.