Effective water saturation

{
  "id": "MLC-T-OAG-001255",
  "term": "Effective water saturation",
  "field": "Oil and gas",
  "definition": "The fraction of the effective pore volume occupied by water, where effective porosity leaves out the water bound to clay minerals. In shaly formations it is lower than total water saturation, because clay-bound water is removed from both the water volume and the pore volume, while irreducible water held by capillary forces is still counted. It is the saturation used to compute hydrocarbon volume from effective porosity.",
  "subject": "Formation Evaluation",
  "url": "https://mlchart.com/terminology/oil-and-gas/effective-water-saturation/"
}