Nomenclature
Variable | Description |
---|---|
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 |
Coefficient which describes the position of the stabilized deliverability line Wellbore storage constant (bbl / psi) |
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 |
Entitlement Management System | |
FCD |
Dimensionless fracture conductivity |
FCD (fault) |
Dimensionless fault conductivity |
FE |
Flow efficiency |
G | Separator gas specific gravity (for fluid properties) |
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) 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) 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) |
MFHW |
Multi-fractured horizontal well |
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 |
Calculated pressure (psia) Critical 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 |
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) |
a |
Matrix block shape factor coefficient |
aD |
Dimensionless phase re-distribution time parameter |
dDt |
An impulse function that dissipates as Dt increases |
f |
Total porosity (fraction) |
ff |
Porosity of the fractures (fraction) |
fm |
Porosity of the matrix (fraction) |
gg(psp) |
Gas specific gravity at a separator pressure of 114.7 psia |
go |
Oil 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) 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) (lbm / 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 (lbm / ft3 or kg / m3) |
rst |
Stock tank oil density (lbm / 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) |