Conventional model
limitations
EQUATIONS
Z
Data demonstrating the impact of in-situ stresses in
UBD of horizontal wells are
often overlooked using conventional models.
\
]
]
]]
]
]]]
[
v v av av
vvava
v v av av
xv aav aa
xvavaa
x v a v av
Researchers have looked
at the effects of in-situ
stresses on the wellbore
and, based on the data,
conducted studies to reveal
the mechanism of wellbore
collapse during overbalanced drilling (OBD). 1 2
Z
\
]
]]
]]]
[
Studies of UBD operations have established a
coupled reservoir-geome-chanics model that simulates the interaction between reservoir flow and
deformation. 3 The model
can determine wellbore-stability design and sand-production risk evaluation
in the formation during
production or UBD. 4 The
model offers a practical
technique to evaluate UBD
of a horizontal well in a depleted reservoir.
\
]
]]
]
]
G
Z
[
\
]]
]
e e
2 2 2 2 2
2 2
2 2 2 2
m ud
2
= + +
= +
= + +
=- +
=- +
= + -
sin
sin
sin
cos
i i i
v
v vvvv ixi
vvvvixi
x x ix i
xx
P
P
v
r m ud
m ud xx yy xx yy xy
z zz xx yy xy
z yz xy
V
V
Q
v {{ v {{
i
!
V
$
()
i
=
=- + + - - -
= - - +
= -
= =
i
Q
QQ
Q
2 2 4 2
2 2 4 2
2 2
0
2
cos sin
cos sin
Q
Q
v v b x b bv b
x vv bx b
2 2
2
= + +
= - +
ii