Page 325 - Intelligent Digital Oil And Gas Fields

270 Intelligent Digital Oil and Gas Fields

ICD is equalized along the horizontal section, which results in an excellent
oil-sweep efficacy from the oil-water contact (OWC) to the wellbore.

7.6.5 Modeling AICDs for Oil Wells

As mentioned in Section 7.2.2, AICD is the newest family of ICDs that
are self-regulating fluidic diodes capable of restricting the flow of fluids
based mainly on differential densities and viscosities. Contrasting with
an ICD, which generates high-flow restriction for heavy oil, the AICD
can sometimes be more feasible in restricting water and gas than a tradi-
tional ICD, which is attributed mainly to the differential density. One of
the main benefits of AICDs is that it can generate spontaneous changes in
fluid flow restriction without control lines, moving parts, or download
mechanical or electrical devices for well intervention and moving
choke size.
In some laboratory experiments with single-phase flow (oil or water),
Least et al. (2012, 2013) showed for the first time the performance of AICDs
using oil fluids from 3 to 200 cPs. They found that the pressure drop across
an AICD valve could be governed by the ratio of fluid density and viscosity
compared with calibrated density and viscosity of the fluid tested at the lab.
To model the subcritical pressure drop across an AICD, the following
equations can be used:

ρ 2 μ β
P out P in ¼ X mix std q α (7.6)
ρ std μ mix
ρ mix ¼ water:vol ρ + oil:vol ρ + gas:vol ρ g (7.7)
o
w
where
P out is the flowing BHP at the outlet in psi,
P in is the flowing BHP at the inlet of the valve in psi,
3
q is the total flow rate of fluids in ft /s,
ρ mix is the fluid density of the mixture phases at pressure and temperature in
3
lbm/ft ,
ρ std is the fluid density measured at laboratory condition used for calibration
3
proposes in lbm/ft ,
ρ o , ρ w , ρ g is the oil, water, and gas densities at pressure and temperature in
3
lbm/ft ,
μ mix is the mixture fluid viscosity calculated at the average of (P out P in )in
cP, μ std is the fluid viscosity measured at laboratory condition used for
calibration proposes in cP,