Page 323 - Intelligent Digital Oil And Gas Fields

268 Intelligent Digital Oil and Gas Fields

pressure drop in front of a high-permeability segment in the horizontal sec-
tion, equalizing the pressure drop along the horizontal section. As a result of
this reduction in pressure drop, the ICDs can reduce the early water or gas
breakthrough (preferably at the heel) and thus increase the oil-recovery fac-
tor. There are different types of ICDs, for example, channel, nozzle, orifice,
helix tube, and hybrid. The most common types applied in the oil field are
the nozzle and helix.
Henriksen et al. (2006) and later on Zhu and Hill (2008) have demon-
strated the importance of ICDs in high-permeability reservoirs and also
demonstrated that the main control property is the pressure-friction losses
generated across the ICD valve. To model the subcritical pressure drop
across an ICD, the following expressions (Eqs. 7.4, 7.5) can be used:

ρ mix h q i 2
P out P in ¼ C (7.4)
2 A Cv
ρ mix ¼ water:vol ρ + oil:vol ρ + gas:vol ρ g (7.5)
w
o
where
C is the conversion factor,
P out is the flowing BHP at the outlet in psi,
P in is the flowing BHP at the inlet of the ICD 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 ,
0.5
Cv is the flow coefficient in USgal/(minpsi ) (which is measured in the lab
of service provider),
ρ o , ρ w , and ρ g are the oil, water, and gas densities at pressure and temperature
3
in lbm/ft ,
water.vol, oil.vol, and gas.vol are the volume fractions of the phases in the
wellbore at time t, and
2
A is the cross-sectional area of the ICD in ft .
Henriksen et al. (2005) and Birchenko (2010) have demonstrated in their
field and simulation studies, respectively, that the permeability distribution
along the horizontal trajectory is the most important parameter to design
ICD types, and determine the number of ICDs required along the horizon-
tal wellbore and the number of packers required. By generating a pressure
drop by using appropriate packer spacing with ICDs, the flow velocity is
reduced, which results in longer sustained oil production before water
and gas breakthrough to the wellbore. They concluded that ICDs could