Nomenclature

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) (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)

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)