Page 319 - Fundamentals of Gas Shale Reservoirs

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c Total fracture compressibility, L F (1/psi) R Solution gas–oil ratio, L /L (SCF/STB)
3
2 ‐ 1
3
t,f so
c Total reservoir compressibility, L F 1 1/ psi R Solution gas–water ratio, L /L (SCF/STB)
2
3
3
t
sw
C Leakoff coefficient in mini‐frac test, L/ T ft / min r Pseudo‐spherical wellbore radius in mini‐DST, L(ft)
L sw
d Effective decline rate s face Skin factor at the face of hydraulic fracture connecting
hf
d Minimum decline rate to the reservoir
min well
D Decline rate, T 1 s hf Skin factor at the well‐hydraulic fracture entrance
D Equivalent binary diffusion coefficient for component (choked fracture)
c
c in the mixture, L /T (cm /s) S Water saturation, (fraction)
2
2
w
D Initial decline rate, T 1 1/ month S Oil saturation, (fraction)
i o
D Knudsen effective diffusion coefficient, L /T (cm /s) S Gas saturation, (fraction)
2
2
Κ *
g
E Young modulus, FL (psi) S Irreducible water saturation, (fraction)
−2
wr
G Cumulative gas production at time t, L (SCF) S Residual oil saturation, (fraction)
3
p or
h Formation thickness, L L(ft) S o,rem Remaining oil saturation, (fraction)
h Open‐hole interval between two packers in mini‐ t Time, T(h, day, month)
p
DST, L(ft) t Dimensionless time
D
1
J Productivity index, L FT 1 BBL Dpsi t i Initial production time, T(day)
5
/
/
k Permeability, L (mD) t Zero time, T(day)
2
0
k Fracture permeability, L (mD) t End of bilinear flow, T(day)
2
f 1
k Effective fracture permeability, L (mD) t End of linear flow, T(day)
2
f,eff 2
k Hydraulic fracture permeability, L (mD) t Production time for well testing, T(h)
2
hf
p
k Matrix permeability, L (mD) t Pumping time for mini‐frac, T(min)
2
m p
k Equivalent spherical permeability, L (mD) T Temperature, ( R)
o
2
sp
/
/
2
m Slope of bilinear flow, FLT 1 4 psih 1 4 T Tensile strength of the formation, FL 2 psi
/
bl
m Slope of semi-log radial flow, FL −2 V Matrix control volume, L (ft )
3
3
r
m
N Cumulative oil production at time t, L (STB) V Pore volume component, L (BBL)
3
3
p R
N(t) Cumulative production at time t, L (STB) w Hydraulic fracture width, L(ft)
3
hf
3
N () Ultimate cumulative production, L (STB) y Fracture half‐length, L(ft)
hf
n Total number of hydraulic fractures y Mole fraction of component c in gas phase, fraction
hf
c
p Pore pressure, FL 2 psi
p Closure pressure in mini‐frac test, FL 2 psi gREEk
c
p Hydraulic fracture propagation pressure, FL 2 psi
hf 2 1 1 1
p i Initial reservoir pressure, FL 2 psi λ Inverse of oil viscosity, LF T ( cp )
o
1
1
2
1
p Matrix pressure, FL 2 psi λ Inverse of oil viscosity, LF T ( cp )
w
m 2 1 1 1
p Oil phase pressure, FL 2 psi λ Inverse of oil viscosity, LF T ( cp )
g
o
p Reservoir static pressure, FL 2 psi η Matrix diffusivity coefficient, k / c t m,
m
r m 2 2
p Flowing bottom‐hole pressure, FL 2 psi LT (ft /D)
wf
p Average pore pressure, FL 2 psi Δp Skin pressure drop in hydraulic fracture stimulated
sf
2
1
3
/
q Production rate, LT ( cc s BBL D) well, FL (psi) 2
/,
3
1
/
q Gas production rate, LT ( cc sSCF D) Δp Well flowing pressure change, FL (psi)
/
,
g ϕ Porosity, fraction
ˆ q Gas production rate per unit rock volume,
g ϕ Matrix porosity, fraction
s 1/
T 1 1/, D m
q Initial oil production rate, LT 1 cc sSTB D ϕ Fracture porosity, fraction
3
/,
/
f
i 2
3
q Oil production rate, LT 1 cc sSTB D μ Oil viscosity, FLT cp
/
/,
o
ˆ q Oil production rate per unit rock volume, σ Matrix shape factor for the cubic matrix blocks,
o 1/L (1/ft )
2
2
s 1/
T 1 1/, D 2
q Water production rate, LT 1 cc sSTB D σ Minimum horizontal stress, FL 2 psi
3
/
/,
h
w
ˆ q Water production rate per unit rock volume, σ Maximum horizontal stress, FL psi
H
w
s 1/
T 1 1/, D ν Poisson ratio
r Radius of spherical matrix block, L(ft) ω Storativity ratio, fraction
m