Definition - What does Effective Porosity mean?
Effective Porosity is the pore volume in a rock that contributes to permeability in a reservoir. It is frequently studied to represent the porosity of sediment or rock available. Porosity which is not considered as effective porosity involves isolated vuggy porosity and water that is bound to clay particles. Porosity is very important when considering the suitability of sediments or rocks as aquifers or as oil or gas reservoirs.
Petropedia explains Effective Porosity
Effective Porosity leads to fluid flow in a reservoir. It does not include isolated pores and volume of pores occupied by water consumed by clay minerals and other grains. It represents the pore space which contains non-clay water and hydrocarbons. The total void space in rocks whether or not it adds to the flow of fluids is referred to as total porosity. Total porosity is typically greater than the effective porosity. Effective Porosity is measured in volume per volume, porosity units, p.u., or percent.