Production Engineering Questions
(a) Production Well (10%)
A well is producing undersaturated oil at conditions where the bubble point pressure is reach
in the tubing well above the perforations. For this well
(i)
(ii)
(iii)
(iv)
(v)
Make a sketch of the ideal inflow performance line/curve, including the variables
on the x and y axes.
Assuming that the well will suffer from near-wellbore deposition at a later time,
add a line/curve illustrating this effect. What is this effect commonly called.
Add to the sketch typical outflow performance curves for two (high and low)
wellhead pressures.
Add to the sketch the point indicating the approximate reservoir pressure.
Name one or more technologies that can be used to increase the production rate
inflow performance of the well?
(b) Oil and Gas Processing (15%)
Oil, gas and water are separated on an offshore platform. After some processing the
(associated) gas is at 82 bara and 20 C. The figure below shown the phase diagram and
hydrate equilibrium line for the gas. The volumetric flow rate at standard conditions is 27.75
MSm3/d (remember that z=1 at standard conditions). The gas is to be compressed to 128 bara
for pipeline export from the platform the 60 km to the receiving terminal on land.
(i)
(ii)
(iii)
Calculate the ideal compression power and the compressor exit temperature
assuming adiabatic conditions.
Based on the temperature calculation above, calculate the temperature of the gas
when it arrives at the receiving terminal on land.
Will hydrate form in the pipeline, and why or why not?
Molecular weight, M = 18.3 kg/kmol
Heat capacity gas, Cp = 2850 J/kg.K
Heat capacity ratio, k = 1.86
Sea temperature, T = 5 C
Pipeline internal diameter, d = 30 inch
Overall heat transfer coefficient, U = 15 W/m2.K
Friction factor pipeline, f = 0.005
Phase envelope and hydrate line for associated gas with molecule weight 18,3 kg/kmol (same
gas as in table above). Pressure scale is from 0 to 120 bara.
Equations (Production Engineering)
q   kA
u
dT
dx
k dp
 dr
p  pwf 
o qo Bo  r 
ln  
2kh  rw 
q  qs.c. Bo
Bo 
V
Vs.c.
N p Bo  V p ct ( pi  pR )
ct  c f  S o co  S wcw
pR  pi 
qo Bo
t
Act h
2kh( pR  pwf )
qo 
  re 

  3 / 4  s 
  rw 

o Bo ln 
qo  PI ( pR  pwf )
pwf  pR 
qg 

 o qo Bo   re 
ln    3 / 4  s 
2kh   rw 

pe
 Ts.c.  1   p 
dp


  re 
  T  ps.c.  pwf   g z 
ln    3 / 4  s 
  rw 

kh
 p 

F ( p)  
 z
 g 
p  gL
 gM
p  po exp 
 zRT

L

P  qp
k 1


m
 k   p2  k


P
RT1 
    1
M
 k  1   p1 


p 
T2  T1  2 
 p1 
k
k 1
k
Cp
Cv
WI 
GCV
T 
K x 


M 1 x 

  Ud 
T2  T  (T1  T ) exp 
L
 mC p 
p  p f  p g  pa
p f 
f L 2
u
2d
d A2 M
d  p 22 
2
2
p 2  p1  ln  2   L  0
f  p1 
f m 2 z RT

f 
0,316
Re 0, 25
Re 
ud


 6,9  n  k 1,11n 
1,8
  log 
 
 
n
f
 Re   3,75d  
n = 1 for væske, n = 3 for gass
1
4 gd
3 fD
uD 
uD  ks
uD 
 L  G
G
 L  G
G
gd 2   L  G 


18  G 

qG s.c.  AG ks  L  G 
G
qG  AG  k s
p  Ts.c.  1


p
 s.c.  T  z
 L  G  L 
 
G  6 
0 , 58
pV  znRT
 kg / m3  
pM
zRT
 p  T 
 z
V  Vs.c.  s.c. 
 p  Ts.c. 
Bg (=FVF gass) =

 T  ps.c. 
V

z
 
Vs.c.  Ts.c.  p 
M gass
M luft
M gass   28,96
R  8314
J
 8,314 kJ / kmol K
kmol.K
Conversion Table
Traditionally units
LENGTH
mile (mi)
yard (yd)
foot (ft)
inch (in)
VOLUME
US-gallon (gal)
UK-gallon (gal)
API barrel (bbl)
kubikkfot (cf)
MASS
pound (lbm)
US-ton (ton)
UK-ton (ton, tonne)
TEMPERATURE
Rankin (R)
Celciusgrader (C)
Fahrenheit (F)
ENERGY, WORK
kalori (cal)
erg
British Termal Unit (BTU)
kilowattime (kwh)
POWER
hestekraft (elektrisk) (hk, hp)
hestekraft (hydraulisk)
FORCE
dyn (dyn)
kilopond, eller kilogramkraft (kp/kgf)
poundforce (lbf)
PRESSURE
bar (bar)
pound per square inch (psi)
atmosfære (atm)
mm kvikksølv (torr)
VISCOSITY
poise (p)
centipoise (cp)
lbf/(ft2/s)
DENSITY
API-gravity (API)
g/cm3
lbm/US-gal
lbm/UK-gal
lbm/ft3
VOLUME FLOW
liter pr. sek. (l/s)
fat pr. dag (bbl/d)
kubikkfot pr. dag (cf/d)
US-gallon pr. minutt (gal/min)
#: Exact value
SI-equivalents
M
1609.344 m #
0.9144 m #
0.3048 m #
0.0254 m #
m3
0.00378541 m3
0.00454609 m3
0.158987 m3
0.0283167 m3
kg
0.45359 kg
907.185 kg
1016.05 kg
Kelvin: K
5/9 K #
K = C + 273
C = (F-32) ∙ 5/9
Joule: J
4.184 J #
10E-7 J
1055.06 J
3600 J
Watt: W
746 W #
746.043 W
Newton: N
10E-5 N #
9.80665 N
4.44822 N
Pascal: Pa
105 Pa
6894.76 Pa
1.01325 bar #
133.322 Pa
Pa.s
10E-1 Pas #
10E-3 Pas #
4.78803 Pas
kg/m3
kg/m3 = (141.5)(1000)/(131.5 + API)
1000 kg/m3 #
119.826 kg/m3
99.7763 kg/m3
16.0185 kg/m3
m3/s
10E-3 m3/s
1.8401E-6 m3/s
3.2774E-7 m3/s
6.30903E-5 m3/s
Useful info.
3 ft = 1 yd
12 in = 1 ft
1 bbl = 42 US gal
1 bbl ~ 5.62 cf
R = F + 460
J = Nm
W = J/s
N = kg m/s2
dyn = g cm/s2
Pa = N/m2
1 bar ~ 14.5 psi
1 atm ~ 14.7 psi
1 atm ~ 1.01 bar
Pa.s = kg/s.m
poise =
dyn/cm2 s