The analysis presented here has been limited for simplicity to the case of single mineral porous rocks. In fact the main parts of the analysis do not change in any significant way if the rock has multiple constituents. The well-known result of Brown and Korringa (1975) states that

K = K_dr + ^2/K_s-/K_+ /K_f
and =_dr,
where *K*_{s} is the unjacketed bulk modulus of the composite solid
frame, is the unjacketed pore modulus of the composite solid
frame, is the appropriate Biot-Willis (1957)
parameter for this situation. The remaining parameters have
the same significance as in (Gassmann). The functional dependence
of *K*_{sat} on the saturation *S* is clearly the same in both
formulas. If we were trying to infer properties of the solid
from these formulas, then of course (BK) would be more difficult
to interpret. But for our present purposes, we are only trying to
infer porosity, saturation values, and saturation state.
For these physical parameters, the analysis goes through without change.

4/28/2000