Page 60 - Fundamentals of Reservoir Engineering

NOMENCLATURE LX

p pc pseudo critical pressure S or residual oil saturation to water
p pr pseudo reduced pressure S w water saturation
p sc pressure at standard conditions S wc connate (or irreducible) water saturation
p wf bottom hole flowing pressure S wf water saturation at the flood front
p wf(1hr) bottom hole flowing pressure rec-orded thickness average water saturation
one hour after the start of flow S w
p ws bottom hole static pressure S w volume averaged water saturation behind an
p ws(LIN) (hypothetical) static pressure on the advancing flood front
extrapolation of the early linear trend of t reciprocal pseudo reduced temperature
the Horner buildup plot (T pc/T)
p average pressure t time
p * specific value of p ws(LIN) at infinite t D dimensionless time
closed-in time 2
t DA dimensionless time (=t Dr /A)
w
∆p pressure drop
∆t closed-in time during a pressure buildup
∆t s closed-in time during a build-up at which
N.B. the same subscripts/superscripts, used
to distinguish between the above p ws(LIN) = p
pressures, are also used in conjunction ∆t d closed in time during a buildup at which
with pseudo pressures, hence: m(p i); p ws(LIN) = pd
m(p wf); m(p ws(LIN)); etc.
T absolute temperature
T transmissibility (McKinley afterflow analysis,
P c capillary pressure ch. 7)
P c ° pseudo capillary pressure T c critical temperature
q production rate T pc pseudo critical temperature
q i injection rate T pr pseudo reduced temperature
Q gas production rate u Darcy velocity (q/A)
r radial distance U aquifer constant
r e external boundary radius v velocity
r D dimensionless radius= r/r w (chs. 7,8) v g relative gas volume, differential liberation
experiment
= r/r o (ch. 9)
V volume
r eD dimensionless radius= r e/r w (chs. 7,8) V net bulk volume of reservoir
= r e/r o (ch. 9) pore volume (PV)
r h radius of the heated zone around a V f
steam soaked well V g cumulative relative gas volume (sc),
differential liberation PVT experiment
r o reservoir radius w width
r w wellbore radius
W D dimensionless cumulative water influx (ch. 9)
r′ w effective wellbore radius taking account
-s
of the mechanical skin (r′ w = r we ) W e cumulative water influx
R producing (or instantaneous) gas oil W ei initial amount of encroachable water in an
ratio aquifer; W ei=c W ip i (ch. 9)
R universal gas constant W i initial volume of aquifer water (ch. 9)

R p cumulative gas oil ratio W i cumulative water injected (ch. 10)
R s solution (or dissolved) gas oil ratio W id dimensionless cumulative water injected
S mechanical skin factor (pore volumes)
S saturation (always expressed as a W iD dimensionless cumulative water injected
fraction of the pore volume) (moveable oil volumes)

S g gas saturation W p cumulative water produced
S gr residual gas saturation to water y reduced density, (Hall-Yarborough
equations, ch. 1)
S o oil saturation
Z Z-factor