This loglan uses the known core derived Sw and porosities to derived the best shaly sand equation and Archie parameters for a field.
The loglan use Genetic Algorithms based on the ‘fitness criterion’ - 'Find the best shaly sand equation so that the resistivity derived Sw matches the core Sw”.
Consequently the loglan not only gives the form of the shaly sand equation but also the cementation exponent m and the saturation exponent n – which normally can only be derived by special core analysis (SCAL). The loglan may ‘re-invent’ the Indonesia, Simandoux, or Poupon equations.
Using core water saturations, it avoids the empirical problems of deriving SCAL parameters at reservoir conditions in the laboratory. It is also very cheap and very fast.