jumonville production on increase, page-16

Momentum:
( ) [ ( ) ] 0
4
1
2
2 2 + + =
∂
+ − + ∂
∂
+ ∂
∂
∂
w
s s w w r
v
g
x
P
v v
x
v
t
ρ αρ α ρ ρ λρ (2)
where α is the void fraction (-), ρs is the density of
steam (kg/m3), vs is the velocity of steam, ρw is the
density of water (kg/m3), vw is the velocity of water,
P is the pressure (Pa), g is the gravitational
acceleration (m/s2), λ is the friction factor (-), and rw
is the well radius (m). The friction factor λ is
evaluated using a two-phase multiplier and is
independent of flow regime (Chisholm, 1973).

It's not oil but you get the drift....