Lumping and De-lumping of Reservoir Fluids

The reservoir fluid usually consists of dozens, even hundreds of components. To perform the fluid property and phase equilibrium calculations for such a large group of mixture is quite time consuming and unpractical, especially to feed them as input to a reservoir simulator to perform simulations. It is, therefore, desirable to reduce that number into a few pseudo-components (usually less than 10) to accurately represent the original mixture. The process requires “lumping” technics in which the critical properties (T_c, P_c and ω) of the individual carbon number fractions are averaged to one set of the critical properties for the lumped pseudo-component or group.     

On the other hand, when performing downstream process simulation, it is required to have the detailed fluid compositions which are heavily lumped in the process of reservoir simulation. Also, the reservoir fluid samples taken and analyzed in-situ often consist of only a few components that require “de-lumping” technics to revert to reservoir fluid as much as possible.   

Lumping and de-lumping technics that couple the calculations in upstream and downstream processes are involved in a serial of the thermodynamic steps.