Empirical correlations to predict gas/gas condensate phase behaviour in sedimentary basins

Correlations to predict the saturated condensate gas ratios of naturally occurring gas-phase petroleums have been derived from a database of PVT data. Significant differences in the behaviour of the saturated CGRs in different petroliferous basins have been identified. Simple polynomial correlations of saturated CGRs against temperature and pressure are presented for the North Sea and Alberta. In addition a global correlation is presented, derived from the whole database. Prediction errors are estimated for all correlations. Due to the variability of saturated CGR behaviour these correlations should be only used in the basins for which they were intended, or those that are known to be analogous. Fresh correlations should be developed and tested for new petroleum systems. The Global correlation is intended only for cases where no other data are available. It is expected that these correlations will be useful for basin modelling and prospect evaluation.