effective water saturation

1. n. [Formation Evaluation]
 The fraction of water in the pore space corresponding to the effective porosity. It is expressed in volume/volume, percent or saturation units. Unless otherwise stated, water saturation is the fraction of formation water in the undisturbed zone. The saturation is known as the total water saturation if the pore space is the total porosity, but is called effective water saturation if the pore space is the effective porosity. If used without qualification, the term water saturation usually refers to the effective water saturation.
Synonyms: water saturation