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) |
|
CL |
Leakoff coefficient (ft/min0.5) |
|
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 |
|
E |
Young’s Modulus (psia) |
|
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 |
|
hf |
Fracture height (ft) |
|
hp |
Height of perforations (ft) |
|
htop |
Top of zone to top of perforations (ft) |
|
ISIP |
Instantaneous Shut-in Pressure (psia) |
|
ISIPeff |
Effective Instantaneous Shut-in Pressure (psia) |
|
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) |
|
(pwf)init |
Sandface injection pressure at the start of injection (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 |
|
Sf |
Fracture stiffness (psia/ft) |
|
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 |
|
Shmin |
Minimum principal stress (psia) |
|
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) |
|
tinj |
Injection 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 |
|
|
Poisson’s ratio |
|
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) |
