The reference temperature is usually the reservoir temperature, but any temperature can be used. The bubble point pressure, also known as the saturation pressure, is the pressure, at some reference temperature, that the first bubble of gas is liberated from the liquid phase. It is not unusual, however, to observe deviations with an order of magnitude higher when applied to other fluids. The correlations typically match the employed experimental data with an average deviation of less than a few percent. The main properties which are determined from empirical correlations are the bubble point, gas solubility, volume, density, compressibility, and viscosity. Many investigators have used PVT laboratory test results, and field data, to develop generalized correlations for estimating properties of reservoir fluids.
The best correlation is the one that matches your data. This is because most of the correlations were developed with regional crude samples. It is difficult to say which correlation should be used when.
This post will discuss PVT properties and correlations that can be used to estimate them. Many times, laboratory data is not available and correlations must be used instead. Ideally, laboratory measured PVT data should be utilized.
