Download Properties of reservoir fluid

Properties of reservoir fluid
Know the fundamental of compressibility of solids, liquids and gases.
Deformation of porous rock, Compressibility of fluid-saturated reservoir rock,
1  V 
 ,
c   
V  p  T
expansion factor
1  V 
   
V  p  p
Know the volumetric and phase behaviour of hydrocarbon system, i.e. the behaviour in dry
gas reservoir, condensate system, volatile oil system and black oil system. Define the different
“lines” in phase diagram (PT- diagrams), like bubble point line, dew point line etc.
Define the Formation volume factor (FVF) for water, oil and gas, and gas-oil ratio. Know the
behaviour of the FVF with different pressure and temperature.
Be familiar with the way to evaluate the reservoir fluid in a laboratory (PVT-analysis), like
Flash liberation, Differential liberation and Flash separation tests.
Derive the equation, Mole fraction gas from separator and mole fraction stock tank oil (STO).
Volume separator gas and STO. Total Gas Oil Ratio(GOR). Oil Formation factor.
Flash equation,
z
 xi   L  Ki V  1
i
z
 yi   L i
V
Ki
Ideal equilibrium ratio equation,
y
Ki  i
xi
Petrophysics
In Porosity it required that you understand the significance and definitions like Absolute
porosity and Effective porosity. Know the different types of pore (Primary intergranular porosity,
Secondary intergranular porosity, intragranular porosity, Vugular porosity, Microscopic and Fracture porosity)
and the different types of porous media (Primary intergranular porosity, Secondary intergranular
porosity)
Know the method to measure the porosity in laboratory and field.

Vp
Vb
It required that you understand the definition of permeability, Absolute and Effective
permeability and the relation between porosity and permeability. Know the application of
Darcy’s law and methods to measure permeability in a laboratory, correct the gas
permeabilities to liquid permeability, Klinkenberg effect.
The Darcy law
k dp
q  A
 dx
In Capillary pressure it is required that you know about the fundamental concepts behind
capillary pressure.
Pc  Pwetting  Pnon wetting
Derive the expression for capillary pressure across a meniscal interface.
In a reservoir with mixed fluid, Relative permeability is important Petrophysics parameter. It
required that you understand the fundamental concept for Relative permeability,
ke  k * kr
Identify the characteristic relative permeability curve for a two-phase fluid. Know the
application of relative permeability and how to measure it in laboratory.
Give an account of the relationship between relative permeability and the rock wettability.
 1
1 
 ;
Pc    
 R1 R2 
Derive the expression for capillary pressure in a pipe
2 ow cos
Pc 
r
Be familiar with the correlation of capillary pressure with the Leverett J-function.
Saturation distribution in reservoirs, like Define and Estimate the free water level (FWL) by
the aid of capillary pressure equation.
Get knowledge of methods to determine the capillary pressure in laboratory.
Fundamental concepts of Drainage- and Imbibition process in pore channels.
Capillary pressure hysteresis
Required that you know the definition of relative permeability and give an account for the
relative permeability curve, oil and water, drainage and imbibition
Define Fractional flow in a reservoir with the aid of Buckley-Leverett’s theory.
Tilted reservoir,

k k  dP

 1  ro  c  g sin   
 o u t  dx


fw  

k 
1  ro w


k rw  o


What require that in a reservoir the flow will behave as a piston displacement?
AL1  S or  S wr   qt t ,
Under which conditions are required deriving the Buckley-Leverett’s equation,
v Swf 
q t df wf
A dS wf
Layered reservoirs
Know about the limitation of Stiles method and the use of the method.
The time of water breakthrough equation in layer i,
 i  o L2
t BT i 
k i k roi P
Dietz stability analysis
It is required that you can utilize the dietz stability equation,
1 Me
tan  
 tan  ,
M e N ge cos 
for a oil-water system and gas-oil system.
Pressure test analysis
Diffusivity equation for a radial flow of slightly compressible fluids (oil, water) and no
crossflow in the reservoir
1   p  1 p
k
, 
r  
r r  r   t
ct
Oil reservoir, Gas reservoir.
Development of the line-source solution based on
x x2
x3
eix    log e x  0.5777  

 ...
1 2.2! 3.3!
to the expression for Line-source solution in practical units,

162,6QB   kt 
  3.23
pwf  pi 
log 
2 
kh
  cw 

It is required that you are familiar with the procedure and the application of a Pressure buildup test. The net pressure drop is given by
Pi  Pt    q log e t  t 
4kh 
t 
Know the use of Matthews-Brons-Hazebroek (MBH) analysis (Horner plot) with the equation
above.
To correlate for a bad near well zone you have to know about the Skin effect,
q
Pskin 
S  qD S
2kh
Derive the equation to determine the Skin in the well,
 Pt   Pwf

kt
S  1.151
 log 10
 3.23
2
m
crw


It required that you know the procedure and the application of a Drawdown test, reservoir
permeability evaluation, correlate for the skin factor, storage capacity of a well and pressure,

qB1.15 
kt
 log

p wf  pi 

0
.
351

0
.
87
S

2kh 
ct rw2

and pressure drawdown test analysis under pseudo steady state conditions;
162.6qB 
4A
S 
 log  2  log C A 

pi  p o 


kh
1
.
151
e
r
w


For gas well testing it is required that you can define the productivity index [PI/J]
In which way become a Back Pressure test accomplished and for what purpose?
Derive the back pressure equation,


n
Qg  C pe2  pw2
Know the way to determine C and n, and define the abbreviations.
In which way become an Isochronous test accomplished and for what purpose?
Reservoir performance analysis
Material balance (MBE)
For a gas reservoir without water influx,
Gi B gi  Gi  G p B g
derive the equation,
P Pi  G p 
 1 

z zi 
G
from the expression above. Be familiar with the application of a p/z plot.
In the aid of MBE for a dry gas reservoir method to determine the initial gas in place (IGIP)
Determine the Gas equivalents in a wet gas reservoir with the help of MBE and Cragoe’s
equation. Equation of state.
Oil Reservoir


N p Bo  R p  Rs Bg 
 Bo  Boi   Rsi  Rs Bg
 Bg

 cw S w  c p
NBoi 
 m
 1  1  m 
B

Boi

 1 Sw
 gi

 
p   We  W p Bw
 
Linear Form
F  N Eo  mE g  Ec   We Bw
In material balance equation it requires that you understand the terms in the equation, Oil
expansion/Shrinkage, liberated gas expansion, Expansion of the gas cap gas and Change in
the HCPV. Be familiar with the terminology/abbreviations and units.
Oil Reservoir (with gas cap and water influx)


N p Bo  R p  Rs Bg 
 Bo  Boi   Rsi  Rs Bg
 Bg

 cw S w  c p
NBoi 
 m
 1  1  m 
B

Boi

 1 Sw
 gi

 
p   We  W p Bw
 
It required also knowledge of the use/area of application of the equation in linear Form for
different reservoir types: Oil reservoir without gas cap, reservoir pressure is above the bubble
point pressure, reservoir pressure below the bubble point pressure. Understand the drive
mechanisms in the reservoir as gas cap drive, natural water drive with gas cap drive, natural
water drive with no gas cap gas and compaction drive. Based on the equation of MBE in
linear form,
F  N Eo  mE g  Ec   We Bw
Gas reservoir with water influx,
G

G p  Gi    We  E
 Ei

Identify the term in the equation under,
F We

 Gi
Ex Ex
W
F
and determine Gi when plotting
versus e
Ex
Ex
Pressure potensial, coning.
Pressure potential equation for water, oil and gas.
i  Pi  g i z i=w,o,g
It is required that you understand the behaviour near the well during production, i.e. gas
coning, water coning and simultaneously gas- and water coning. Derive the maximum flow to
avoid second or third fluid to be produced. (With help of pressure potential for all fluid)
Maximum oil flow to avoid producing water equation,
g  w   o k o 2
q o ,max  
h  D2 .
re
 o ln
rw

