Friday, September 9, 2011


a = Matrix block shape factor coefficient
aD = Dimensionless phase re-distribution time parameter
dDt = An impulse function which dissipates as Dt increases
f = Total porosity (fraction)
ff = Porosity of the fractures (fraction)
fm = Porosity of the matrix (fraction)
gg = Gas specific gravity
gg(psp) = Gas specific gravity at a separator pressure of 114.7 psia
go = Oil specific gravity
gw = Water specific gravity
l = Interporosity flow coefficient
m = Fluid viscosity (cp)
m1 = Fluid viscosity in zone 1 (cp)
m2 = Fluid viscosity in zone 2 (cp)
mg = Gas viscosity (cp)
mgi = Gas viscosity at initial pressure (pi) (cp)
mo = Undersaturated oil viscosity (cp)
mob = Oil viscosity at the bubble point (cp)
mod = Dead-oil or gas-free oil viscosity (cp)
mos = Gas-saturated oil viscosity (cp)
mw = Water viscosity (cp)
q = Azimuth angle of wellbore (degrees)
q = Wedge angle of wellbore (degrees)
qr = Relative temperature
qw = Angle of inclination of the well, measured in degrees from a normal to the formation bedding plane (angle of slant)(degrees)
r = Liquid density (lbm / ft3 or kg / m3)
rbs= Pseudo-liquid density at reservoir pressure and standard temperature (60 °F) (lb/ ft3 or kg / m3)
rg = Gas density (lbm / ft3 or kg / m3)
ro = Undersaturated oil density (lbm / ft3 or kg / m3)
rob = Oil density at the bubble point (g / cm3)
rpo = Pseudo-liquid density at standard conditions (lb/ ft3 or kg / m3)
rst = Stock tank oil density (lb/ ft3 or kg / m3)
s = Inclination angle of wellbore (degrees)
w = Storativity ratio
y = Pseudo-pressure (psi2 / cp)
y* = Extrapolated pseudo-pressure (psi2 / cp)
Dy = Delta pseudo-pressure (psi2 / cp)
y2p = Two-phase pseudo-pressure (psi2 / cp)
yi = Initial pseudo-pressure (psi2 / cp)
yR = Average reservoir pseudo-pressure (psi2 / cp)
yR = Average reservoir pseudo-pressure obtained by shut-in of the well to complete stabilization (psi2 / cp)
yw = Wellbore pseudo-pressure (psi2 / cp)
ywf = Flowing pseudo-pressure (psi2 / cp)
ywfo = Final flowing pseudo-pressure (psi2 / cp)
ywo = Initial cushion pseudo-pressure (psi2 / cp)
yw1 = Cushion pseudo-pressure before downhole shut-in (psi2 / cp)
yws = Shut-in pseudo-pressure (psi2 / cp)
yws* = Extrapolated shut-in pseudo-pressure (psi2 / cp)
a = LIT flow equation coefficient
A = Drainage area (ft2)
Awb = Effective wellbore area (ft2)
AOF = Absolute open flow potential (gas) (MMcf / d)
b = LIT flow equation coefficient
B = Liquid formation volume factor (Rbbl / stbbl)
Bg = Gas formation volume factor (Rbbl / scf or Rbbl / MMscf)
Bgi = Gas formation volume factor at initial pressure (Rbbl / scf or Rbbl / MMscf)
Bo = Oil formation volume factor (Rbbl / stbbl)
Boi = Oil formation volume factor at initial pressure (pi) (Rbbl / stbbl)
Bob = Oil formation volume factor at the bubble point (Rbbl / stbbl)
Bw = Water formation volume factor (Rbbl / stbbl)
C = Wellbore storage constant (bbl / psi)
C = Coefficient which describes the position of the stabilized deliverability line
CaD = Dimensionless apparent storage constant
CD = Dimensionless wellbore storage constant
CpD = Dimensionless pressure parameter
ce = Effective compressibility (1 / psia)
cf = Formation compressibility (1 / psia)
cfrac = Compressibility of the fractures (1 / psia)
cg = Gas compressibility (1 / psia)
cgi = Gas compressibility at initial pressure (pi) (1 / psia)
cm = Compressibility of the matrix (1 / psia)
co = Oil compressibility (1 / psia)
ct = Total compressibility (1 / psia)
cti = Total compressibility at initial pressure (pi) (1 / psia)
cw = Water compressibility (1 / psia)
cwb = Wellbore fluid compressibility (1 / psia)
D = Turbulence factor
Der = Derivative
Ddatum = Datum depth (ft)
Dlayer = Depth of layer (ft)
DR = Damage ratio
Ecurv = Curvature error
Epres = Pressure error
Erate = Rate error
ETLS = Total least squares error
FCD = Dimensionless fracture conductivity
FCD (fault) = Dimensionless fault conductivity
FE = Flow efficiency
GIP = Gas-in-place (MMscf)
Gliq = Liquid gradient (psi / ft)
Gp = Cumulative gas production (MMscf)
h = Net pay (ft)
hD = Dimensionless pay thickness
hp = Height of perforations (ft)
htop = Top of zone to top of perforations (ft)
k = Permeability (md)
k1 = Permeability of reservoir zone containing the well (zone 1) (md)
kf = Fracture permeability (md)
kfck = Permeability of the choked portion of fracture (md)
kfwf = Fracture flow capacity (md ft)
(kfwf)D = Dimensionless fracture flow capacity
kfault = Fault permeability (md)
kh = Horizontal permeability (md)
kh / kv = Horizontal to vertical permeability ratio
km = Matrix permeability (md)
kro = Relative permeability to oil (ko / K)
krg = Relative permeability to gas (kg / K)
ks = Spherical permeability (md)
ks = Permeability of the damaged zone (md)
kv = Vertical permeability (md)
kx = Permeability in x-direction (md)
kxy = Horizontal permeability (md)
ky = Permeability in y-direction (md)
kyz = Vertical permeability (md)
kz = Permeability in z-direction (md)
K = Absolute permeability (K = kg / krg or K = ko / kro)
L = Liquid volume (ft3)
L = Horizontal wellbore length (ft)
Le = Effective wellbore length (ft)
Lfault = Distance between the well and fault (ft)
m = Semi-log slope
m(p) = Two-phase pseudo-pressure (psi2 / cp)
n = Inverse slope of the stabilized deliverability line (varies between 1.0 for completely laminar flow and 0.5 for fully turbulent flow)
Np = Cumulative oil production (stbbls)
Nw = Number of segments
OGIP = Original gas-in-place (MMscf)
OIP = Oil-in-place (bbls)
OOIP = Original oil-in-place (bbls)
p = Pressure (psia)
p* = Extrapolated pressure (psia)
Dp = Delta pressure (psia)
p = Average reservoir pressure (psia)
p1 = Pressure at fault boundary in zone 1 (psia)
p2 = Pressure at fault boundary in zone 2 (psia)
pbp = Bubble point pressure (psia)
pc = Critical pressure (psia)
pc = Calculated pressure (psia)
pD = Dimensionless pressure
DpD = Delta dimensionless pressure
pdew = Dew point pressure (psia)
pfault = Pressure at fault boundary within the fault (psia)
pflow = Specified flowing pressure (psia)
pi = Initial reservoir pressure (psia)
pi(syn) = Synthetic initial reservoir pressure (psia)
pm = Measured pressure (psia)
ppD = Dimensionless anomalous pressure
pr = Reduced pressure
pR = Average reservoir pressure obtained by shut-in of the well to complete stabilization (psia)
pR = Average reservoir pressure (psia)
psc = Standard pressure (14.696 psia)
Dpskin = Pressure drop due to skin (psia)
psp = Separator pressure (psia)
pw = Wellbore pressure (psia)
pwD = Dimensionless wellbore pressure
pwf = Flowing pressure (psia)
pwfo = Final flowing pressure (psia)
pwo = Initial cushion pressure (psia)
pws = Shut-in pressure (psia)
pws* = Extrapolated shut-in pressure (psia)
PI = Productivity Index (bbls / d / psia)
PPD = Primary pressure derivative
Pu = The unit rate pressure response of the reservoir
q = Fluid Rate (MMscf / d or bbls / d)
q* = Extrapolated straight line oil rate (stbbl / d)
qc = Calculated fluid rate (MMscf / d or bbls / d)
qg = Gas rate (MMscf / d)
qm = Measured fluid rate (MMscf / d or bbls / d)
qo = Oil rate (stbbl / d)
qo(max) = Maximum oil flow rate (stbbl / d)
qst = Gas flow rate at standard conditions (MMscf / d)
qt = Total gas flow rate (MMscf / d)
qtBt = Total (in-situ) fluid rate (bbls / d)
qw = Water rate (bbl / d)
re = Radial extent of zone (ft)
reff = Effective wellbore radius (ft)
rinv = Radius of investigation (ft)
rs = Equivalent spherical wellbore radius (ft)
rw = Wellbore radius (ft)
rwa = Apparent wellbore radius (ft)
rwc = Corrected wellbore radius (ft) for htop > 0 (rwc = rw for htop = 0)
R = Gas constant (10.73 ft3 psia / lbmol °R)
Rs = Solution gas oil ratio (scf / stbbl or MMscf /stbbl)
Rsb = Solution gas oil ratio at the bubble point (scf / stbbl or MMscf /stbbl)
Rsr = Reduced solution gas oil ratio
R.I. = Rate integral
s = Skin
s' = Total (effective) skin
s2p = Two-phase skin
sc = Choked fracture skin
sd = Skin due to damage
sdp = Interporosity skin
sf = Skin on fracture face
sfault = Skin across the fault
sinc = Skin due to inclination
spp = Skin due to partial penetration
sturb = Skin due to turbulence
sXf = Skin due to Xf
Sg = Gas saturation (fraction)
Sgi = Initial gas saturation (fraction)
S.I. = Sandface integral
So = Oil saturation (fraction)
Soi = Initial oil saturation (fraction)
Sw = Water saturation (fraction)
Swi = Initial water saturation (fraction)
t = Time (hr)
Dt = Delta time (hr)
ta = Pseudo-time (hr)
Dta = Delta pseudo-time (hr)
tc = Effective producing time (hr)
tD = Dimensionless time
tDA = Dimensionless time based on drainage area
tDXf = Dimensionless time based on Xf
te = Equivalent time (hr)
tflow = Specified flow time (hr)
tp = Producing time (hr)
tshut-in = Specified shut-in time (hr)
T = Reservoir temperature (°F or °R)
Tc = Critical temperature (°R)
Tpp = Pour point temperature (°C)
Tsc = Standard temperature (60 °F)
Tsp = Separator temperature (°F)
uf1 = Fluid flux at fault boundary from zone 1 to fault
uf2 = Fluid flux at fault boundary from zone 2 to fault
V = Vapor volume (ft3)
Vp = Pore volume (ft3)
Vw = Wellbore volume (bbls)
Vw1 = Wellbore volume before downhole shut-in (bbls)
Vw2 = Wellbore volume after downhole shut-in (bbls)
Vu = Wellbore volumetric capacity (bbls / ft)
Vresv = Fluid volume at reservoir conditions (Rbbls)
Vsurface = Fluid volume at surface conditions (scf or stbbls)
W = Original water in place (stbbls)
WIP = Water-in-place (bbls)
w = Channel width (ft)
wck = Width of the choked portion of fracture (ft)
wcurv = Curvature error weighting
wf = Fracture width (ft)
wfault = Fault width (ft)
wpres = Pressure error weighting
wrate = Rate error weighting
ws = Depth of fluid-loss damage into the formation and normal to the fracture face (ft)
Wp = Cumulative water production (stbbls)
Xck = Length of the choked portion of fracture (ft)
Xe = Reservoir length (ft)
Xf = Fracture half-length (ft)
Xw = Well location in x-direction (ft)
Ye = Reservoir width (ft)
Yw = Well location in y-direction (ft)
z = Gas compressibility factor
zi = Gas compressibility factor at pi
zm = Distance between the top of the productive zone and the middle of the open interval (ft)
Zw = Well location in z-direction (ft)
DXo = Distance of observation well from active well (x-direction) (ft)
DYo = Distance of observation well from active well (y-direction) (ft)
Zo = Distance of observation well from top of zone (z-direction) (ft)


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