## Brief notes on the CREWES Fluid Property Calculator

This Calculator is designed to produce information on pore fluids of interest in petroleum exploration. It is intended for use in connection with seismic fluid substitution operations.

The Gas Phase calculations may be carried out in either of two ways. Those using mole fraction input employ the Peng-Robinson equation of
state in order to calculate acoustic properties. Those using the gas density ratio as input employ empirical relations described by
Batzle & Wang (1992). Viscosity is calculated only by the empirical equation route.

The Liquid Phase calculations employ empirical relations which are based on Batzle & Wang, but which vary slightly from them for some of the properties:

- The density and velocity calculations for dead oil are the same as for Batzle & Wang (their eqs 18-20)
- The density calculations for live oil vary from Batzle and Wang. The latter are given by their eqs 23 and 24; while the FPE (Fluid Property Explorer) calculations are similar, but in eqn 24 they employ ρ
_{P} instead of ρ_{0}.
- The velocity calculations for live oil also vary from Batzle & Wang. The latter are given by substituting a pseudodensity (defined in equation 22) into eqn 20b, and the FPE calculations are similar but involve multiplying the pseudodensity by an additional factor of
*B*_{0} (eq 23) evaluated at *R*_{G} = 0.
- The viscosity calculations for a live oil are the same for Batzle & Wang and for FPE as given in eqns 25 and 26, following the procedure in the paragraph which follows equations 25 and 26.
- A feature of the above changes to the Batzle & Wang approach is that they result in live oil results reducing to dead oil results for
*R*_{G} = 0. This would be desirable if the *R*_{G} = 0 limit of live oil is dead oil, but may not be if there is residual dissolved gas at *R*_{G} = 0.

The Brine Phase calculations also employ empirical relations as given by Batzle & Wang.

The Multi-Phase
calculations employ simple volume fraction averaging for the density and Wood's relation for the bulk modulus. The velocity is calculated
from the resulting density and bulk modulus. The viscosity is not calculated in the multi-phase case.

For questions or suggestions regarding this applet, contact crewesinfo@crewes.org.

### References

- Batzle, M. and Wang, Z., 1992, Seismic properties of pore fluids:
Geophysics,
**57**, 1396-1408.
- Peng, D.-Y. and Robinson, D. B., 1976, A New Two-Constant Equation of State: Ind. Eng. Chem., Fundam.,
**15**, 59-64.

Copyright, 2015, CREWES, University of Calgary