How is capillary pressure curve used to determine the initial distribution of fluids in a reservoir?
If you know the rock quality, namely porosity and permeability of the rock at a certain depth in the reservoir, you can use the capillary pressure (determined from the difference in densities between water and hydrocarbon and the height above the Free Water Level) to determine the initial water saturation of the …
What is capillary pressure curve?
The relationship describing the capillary pressure required to obtain a given nonwetting phase saturation in a rock. The capillary pressure curve is important for understanding saturation distribution in the reservoir and affects imbibition and multiphase fluid flow through the rock.
What is capillary entry pressure?
By definition, the minimum capillary entry pressure, also known as breakthrough pressure, is the pressure at which the non-wetting phase starts to displace the wetting phase, usually brine, contained in the largest pore throat within a water-wet formation.
What increases capillary pressure?
Elevations in arterial (Pa) or venous (Pv) pressure increase capillary pressure, which favors enhanced capillary filtration (Jv).
What is the formula for capillary rise?
The formula for capillary rise (h) = 2T/rρg.
What is free water level?
The free water level is located at the base of a hydrocarbon column and the transition zone. Above this level, the reservoir produces water alone, hydrocarbon and water, or hydrocarbon alone on a production test. Below this level lies the aquifer of a water drive reservoir system.
What is a normal capillary pressure?
Capillary pressure physiology Normal capillary pressure, measured at the apex of the capillary loop with the capillary at heart level, ranges from 10.5 to 22.5 mmHg (Figure 4). It is lower in premenopausal women than in postmenopausal women or in men and does not correlate with brachial artery blood pressure.
How is capillary pressure calculated?
Capillary pressure (Pc) is the difference in pressure measured across the interface in the capillary (Pc = Pnw – Pw). This pressure results from the contrast in pressure gradients caused by the different densities of the nonwetting (ρnw) and wetting (ρw) phases (right).
Why are capillary tubes small?
Capillarity is the result of surface, or interfacial, forces. The rise of water in a thin tube inserted in water is caused by forces of attraction between the molecules of water and the glass walls and among the molecules of water themselves. The narrower the bore of the capillary tube, the higher the water rises.
How to calculate the capillary pressure of a reservoir?
At any time, saturation of the non-wetting phase (So) equals (1 – Sw). In a gas expansion drive reservoir Sw = (1 – So) stays relatively constant over time. Capillary pressure curves help to explain the behaviour of water drive reservoirs but do little for gas expansion or gas cap reservoirs with no water drive.
How is the capillary pressure curve different from the drainage curve?
The capillary pressure curve is different for these two processes, as shown in the illustration at the right. Most capillary pressure graphs show only the drainage curve. Fluid flow process in which the saturation of the nonwetting phase increases.
Why is the capillary pressure of a seal rock important?
Evaluating capillary pressure of potential reservoir and seal rocks is important because capillarity controls the static distribution of fluids in the reservoir prior to production and remaining hydrocarbons after primary production. Figure 1 Effects of interaction of adhesive and cohesive forces on wettability.
How are fluid saturation and capillary pressure related?
This, and the related gas and water saturations are controlled by capillary pressure. The pore space in a rock is occupied by fluids. In hydrocarbon reservoirs these fluids are hydrocarbon gasses, oil and an aqueous brine. We define the pore fraction of each of these asS g, S oandS w, respectively. Hence, S g+ S o+ S w= 1.
