Asked by: Melissa Williams
Connate water saturation is the amount of the water which adsorbs on the surface of the grains of the rock or on the walls of the porous pore channels (immobile with the traditional displacement methods) divided by the pore volume.
How do you calculate saturation of water?
The basis of Archie’s equation (Archie, 1942), conventionally used to calculate the water saturation of a formation, is that the conductivity of the formation is a function of the conductivity of the fluid content in its pore space and therefore the equation can be written in terms of conductivity as:(1) S w = [ ( a ∗
What is the difference between irreducible and connate water saturations?
The term is somewhat imprecise because the irreducible water saturation is dependent on the final drive pressure (when flowing oil or gas) or the maximum speed of rotation (in a centrifuge). The related term connate water saturation is the lowest water saturation found in situ.
What is connate water in reservoir?
Connate water is water trapped in the pores of sedimentary rocks (depositional water). Formation water is water found in deeply buried, porous, and permeable sedimentary rocks .
What is water saturation in well log?
The saturation in water or hydrocarbon is an important petrophysical parameter used for the evaluation of oil and gas reservoirs. It represents the amount of hydrocarbons in a reservoir. There are many relations to determine the water saturation from well logs by using the physical properties of rocks.
How is irreducible water saturation measured?
The laboratory measurements of Nuclear Magnetic Resonance (NMR) in conventional reservoirs provide accurate levels of mobile water and irreducible water saturation which is the sum of clay bound water and capillary bound water (BVW + BVI).
What is connate water in geology?
In geology and sedimentology, connate fluids are liquids that were trapped in the pores of sedimentary rocks as they were deposited. These liquids are largely composed of water, but also contain many mineral components as ions in solution.
How can you find saturation from logs?
Techniques for calculating water saturation
Sw in wellbores can be determined by the following primary methods: Sw calculations from resistivity well logs by application of a model relating Sw to porosity, connate-water resistivity, and various rock electrical properties.
How do you find the degree of saturation?
Degrees of unsaturation is equal to 2, or half the number of hydrogens the molecule needs to be classified as saturated. Hence, the DoB formula divides by 2. The formula subtracts the number of X’s because a halogen (X) replaces a hydrogen in a compound.
What is the unit of water saturation?
The fraction of water in a given pore space. 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.
What is critical water saturation?
Critical water saturation is the upper limit for formation water saturation above which a specific sample will produce a significant percentage of water with hydrocarbons. For many years, critical water saturation has been estimated from routine porosity and permeability data.
What is water Vapour saturation?
The saturation vapour pressure is the pressure at which water vapour is in thermodynamic equilibrium with its condensed state. At pressures higher than vapour pressure, water would condense, whilst at lower pressures it would evaporate or sublimate.