SPWLA Glossary

An empirical correction applied to porosity derived from the sonic log in uncompacted formations such as sands at shallow depths or formations under abnormally high pressures.

In applying the empirical correction to the time-average relationship for obtaining apparent porosities from interval transit times, the relationship becomes:

where C_p is the compaction-correction coefficient; other symbols as described in time-average relationship. In consolidated formations C_p = 1 (corresponding to no correction). In unconsolidated formations (which generally occur at shallow depths) C_p has values greater than 1.