Basic Reservoir Engineering - Mai Cao Lan
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GEOPET BACHELOR PROGRAM INPETROLEUM ENGINEERING
BASIC RESERVOIR
ENGINEERING
5/2/2013 1Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Learning Objectives
At the end of this lecture, you should be able to understand the
fundamentals of reservoir engineering and do some basic
analyses/calculations as follows:
PVT Analysis
Special Core Analysis
Well Test Analysis
Production Forecast
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References
1. L.P.Dake (1978). Fundamentals of Reservoir Engineering,
Elsevier Science, Amsterdam.
2. L.P.Dake (1994). The Practice of Reservoir Engineering,
Elsevier Science, Amsterdam.
3. B.C.Craft & M.Hawkins (1991). Applied Petroleum
Reservoir Engineering,Prentice Hall, New Jersey.
4. T. Ahmed (2006). Reservoir Engineering Handbook , Gulf
Professional Publishing, Oxford.
5/2/2013 3Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Outline
Key Concepts in Reservoir Engineering
Fundamentals of Oil & Gas Reservoirs
Quantitative Methods in Reservoir Characterization and
Evaluation.
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Part I
5/2/2013 5Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Key Concepts in
Reservoir Engineering
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Definition of Reservoir
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In petroleum industry, reservoir fluids is a mixture of hydrocarbons (oil and/or gas), water and other non-hydrocarbon compounds (such as H2S, CO2, N2, ...)
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Definition of Engineering
Engineering is the discipline or profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
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Definition of Engineering
Engineering is the discipline and profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
5/2/2013 8Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Necessary Knowledge
Knowledge about oil & gas reservoirs
Reservoir Rock Properties & Behavior during the
Production Process
Reservoir Fluid Properties & Behavior during the
Production Process
Fluid Flows in Reservoirs
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Necessary Knowledge (cont’d)
Technical & Scientific Knowledge
Quantitative Methods for Reservoir
Characterization
Quantitative Methods for Reservoir
Evaluation
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Definition of Engineering
Engineering is the discipline and profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
5/2/2013 11Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Physical Resources
In-place Reservoir Resources
Reservoir’s energy source resulted from the
initial pressure & drive mechanisms during
production
Available flow conduits thanks to reservoir’s
characteristic properties such as permeability
distribution.
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Definition of Engineering
Engineering is the discipline and profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
5/2/2013 13Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Design and Implementation
Design and Implement an Oil Field Development Plan
Plan for producing oil & gas from the reservoirs in the
field: Exploit reservoir energy sources; Design
appropreate well patterns; Select suitable subsurface &
surface facilities ... during the lifecycle of the oil field
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Definition of Engineering
Engineering is the discipline and profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
5/2/2013 15Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Desired Objective
To Maximize the profit resulted from the
recovered oil & gas
To recover as much as possible oil & gas from
the reservoirs
To recover high-quality oil & gas
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Definition of Engineering
Engineering is the discipline and profession of
applying necessary knowledge and utilizing
physical resources in order to design and
implement systems and processes that realize a
desired objective and meet specified criteria.
5/2/2013 17Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Specified Criteria
Money associated with hired manpower,
facilities, technologies, ...
Time
Local regulations
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Oil Fields and Their Lifecycle
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Oil Fields and Their Lifecycle
A lifecycle of an oil field consists of the following stages:
Exploration
Appraisal
Development
Production
Abandonment
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Revenue Throughout LifeCycle
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Part II
5/2/2013 22Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Basic Properties and
Behaviors of
Oil & Gas Reservoirs
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Five Basic Reservoir Fluids
Black Oil
Criticalpoint
Pre
ss
ure
, p
sia
Separator
Pressure pathin reservoir Dewpoint line
% Liquid
Temperature, °F
Pre
ss
ure
Temperature
Separator
% Liquid
Volatile oil
Pressure pathin reservoir
3
2
1
3
Criticalpoint
3
Separator
% Liquid
Pressure pathin reservoir
1
2Retrograde gas
Critical
pointPre
ss
ure
Temperature
Pre
ss
ure
Temperature
% Liquid
2
1
Pressure pathin reservoir
Wet gas
Criticalpoint
Separator
Pre
ss
ure
Temperature
% Liquid
2
1
Pressure pathin reservoir
Dry gas
Separator
Retrograde Gas Wet Gas Dry Gas
Black Oil Volatile Oil
5/2/2013 23Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Classification of Reservoir Fluids
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Used to visualize the fluids production path from
the reservoir to the surface
Used to classify reservoir fluids
Used to develop different strategies to produce
oil/gas from reservoir
Pressure-Temperature Diagrams
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Phase Diagrams
Single
Liquid
Phase
Region
CriticalPoint
Pre
ssu
re,
psia
Initial Reservoir
State
% Liquid
Temperature, °F
Cricondentherm
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Separator
Cricondenbar
Single
Gas
Phase
Region
Two-Phase
Region
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Black Oil
Black Oil
CriticalPoint
Pre
ssu
re,
psia
Separator
Pressure pathin reservoir
Dewpoint line
% Liquid
Temperature, °F
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Volatile-Oil P
ressu
re
Temperature, °F
Separator
% Liquid
Volatile oil
Pressure pathin reservoir
2
1
3
Criticalpoint
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Retrograde Gas
3
Separator
% Liquid
Pressure pathin reservoir
1
2Retrograde gas
Critical point
Pre
ssu
re
Temperature
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Wet GasP
ressu
re
Temperature
% Liquid
2
1
Pressure pathin reservoir
Wet gas
Criticalpoint
Separator
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Dry GasP
ressu
re
Temperature
% Liquid
2
1
Pressure pathin reservoir
Dry gas
Separator
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Field Identification
Black Oil
Volatile Oil
Retrograde Gas
Wet Gas
Dry Gas
Initial Producing Gas/Liquid Ratio, scf/STB
<1750 1750 to 3200
> 3200 > 15,000* 100,000*
Initial Stock-Tank Liquid Gravity, API
< 45 > 40 > 40 Up to 70 No Liquid
Color of Stock-Tank Liquid
Dark Colored Lightly Colored
Water White
No Liquid
*For Engineering Purposes
5/2/2013 31Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Laboratory Analysis
Black Oil
Volatile Oil
Retrograde Gas
Wet Gas
Dry Gas
Phase Change in Reservoir
Bubblepoint Bubblepoint Dewpoint No Phase Change
No Phase
Change Heptanes Plus, Mole Percent
> 20% 20 to 12.5 < 12.5 < 4* < 0.8*
Oil Formation Volume Factor at Bubblepoint
< 2.0 > 2.0 - - -
*For Engineering Purposes
5/2/2013 32Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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0
50000
0 30Heptanes plus in reservoir fluid, mole %
Init
ial p
rod
uc
ing
gas/o
il r
ati
o, scf/
ST
B
Dewpoint gas
Bubblepoint oil
Retrograde
gas
Volatile
oil
Wet
gas
Dry
gas
Black
oil
5/2/2013 33Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Field Identification
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34Flui
ds & Fluid
Primary Production TrendsG
OR
GO
R
GO
R
GO
R
GO
R
Time Time Time
TimeTimeTimeTimeTime
TimeTime
No
liquid
No
liquid
Dry
Gas
Wet
Gas
Retrograde
Gas
Volatile
Oil
Black
Oil
A
PI
A
PI
A
PI
A
PI
A
PI
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Exercise 1
Based on the phase diagrams of volatile oil
and retrograde gas, describe some
characteristic properties of these two
reservoir fluids
Name some applications of phase diagrams
in selecting surface facilities
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Basic Properties of Natural Gas
5/2/2013 36Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Equation-of-State (EOS)
Apparent Molecular Weight of Gas Mixture
Density of Gas Mixture
Gas Specific Gravity
Z-factor (Gas Compressibility or Gas Deviation
Factor)
Isothermal Compressibility
Gas Formation Volume Factor
Gas Viscosity
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Gas Equation-Of-State (EOS)
5/2/2013 37Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
pV nZRTEquation of State:
Quantity Description Unit/Value
p Pressure psia
V Volume ft3
n Mole Number lb-mol
Z Gas Deviation
Factor
dimensionless
T Temperature Rankine
R Universal Gas
constant
10.73
psia.ft3/lb-mole. R
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Apparent Molecular Weight of a Gas Mixture
5/2/2013 38Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Normally, petroleum gas is a mixture of various light hydrocarbon (C1-C4). For example:
Component Mole PercentMolecular Weight
(lb/lb-mol)
Critical Critical
Pressure Temperature
(psia) (oR)
(1) (2) (3) (4)
C1 0.85 16.043 666.4 343.00
C2 0.04 30.070 706.5 549.59
C3 0.06 44.097 616.0 665.73
iC4 0.03 58.123 527.9 734.13
nC4 0.02 58.123 550.6 765.29
1
20.39N
a i i
i
M y M
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Density of Gas Mixture
5/2/2013 39Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Gas density is calculated from the definition of density and the EOS
3pM= = (lb/ft )
g a ag
g
m nM p
V nZRT ZRT
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Gas Specific Gravity
5/2/2013 40Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The specific gravity is defined as the ratio of the gas density to that of the air
M= =
28.97
g a ag
air air
M
M
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Gas Deviation Factor (Z-factor)
5/2/2013 41Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Z-factor in the EOS accounts for the difference in the behavior of natural gases in compared with ideal gases.
;pr pr
pc pc
p Tp T
p T
Z-factor can be expressed as: Z=Z(ppr,Tpr) where
;pc i ci pc i ci
i i
p y p T yT
ppr: pseudo-reduced pressureTpr: pseudo-reduced temperatureppc: pseudo-critical pressureTpc: pseudo-critical temperature
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Standing-Katz Chart
5/2/2013 42Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Step 1: Calculate pseudo-critical pressure and temperature
Step 2: Calculate pseudo-reduced pressure and temperature:
Step 3: Use Standings-Katz chart to determine Z
;pr pr
pc pc
p Tp T
p T
;pc i ci pc i ci
i i
p y p T yT
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Dranchuk & Abou-Kassem Correlation
5/2/2013 43Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
7210.0;6134.0
1056.0;1844.0;7361.0
5475.0;05165.0;01569.0
5339.0;0700.1;3265.0
1110
987
654
321
AA
AAA
AAA
AAA
2 5 2 2 221 3 4 5 11 11
3 4 5
1 1 2 3 4 5
2
2
3 6 7 8
2
4 9 7 8
3
5 10
( ) (1 )exp( ) 1 0
0.27 / ( )
/ / / /
0.27 /
/ /
( / / )
/
r r r r r r r
r
r pr pr
pr pr pr pr
pr pr
pr pr
pr pr
pr
RF R R R R A A
p ZT
R A A T A T A T A T
R p T
R A A T A T
R A A T A T
R A T
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Exercise 2
Component yi Mi Tci,°R pci
CO2 0.02 44.01 547.91 1071
N2 0.01 28.01 227.49 493.1
C1 0.85 16.04 343.33 666.4
C2 0.04 30.1 549.92 706.5
C3 0.03 44.1 666.06 616.4
i - C4 0.03 58.1 734.46 527.9
n - C4 0.02 58.1 765.62 550.6
5/2/2013 44Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Wichert-Aziz Correction Method
R , o pcpc TT
2 2
, psia(1 )
pc pc
pc
pc H S H S
p Tp
T y y
Corrected pseudo-critical temperature:
Corrected pseudo-critical pressure:
2 2 2 2 2 2
0.9 1.60.5 4.0120 15 ,H S CO H S CO H S H Sy y y y y y
Pseudo-critical temperature adjustment factor
5/2/2013 45Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Exercise 3
Component Mole fraction
C1 0.76
C2 0.07
CO2 0.1
H2S 0.07
Given the following real gas composition,
Determine the density of the gas mixture at 1,000 psia and 110 F using Witchert-Aziz correction method.
5/2/2013 46Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Sutton Correction Method
20.5
o
o
1 2, R/psia
3 3
, R/psiai
i
c ci i
i ic ci i
c
i
i c
T TJ y y
p p
TK y
p
Step1: Calculate the parameters J and K:
77
7 7
7 7 7
7
20.5
2 2
2 3
1 2
3 3
0.6081 1.1325 14.004 64.434
0.3129 4.8156 27.3751
c cJ
c cC C
J J J J C J C
cK C C C
c C
T TF y y
p p
F F F y F y
Ty y y
p
Step 2: Calculate the adjustment parameters:
5/2/2013 47Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Sutton Correction Method (cont.)
K
J
KK
JJ
Step 3: Adjust the parameters J and K
J
Tp
J
KT
pc
pc
pc
2
Step 4: Calculate the adjusted pseudo-critical terms
5/2/2013 48Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Correlations for Pseudo Properties of Real Gas Mixture
5/2/2013 49Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Isothermal Compressiblity of Natural Gas Mixture
1 d
dg
Vc
V p
By definition, the compressibility of the gas is
1 1g
T
dzc
p z dp
Isothermal pseudo-reduced compressibility:
5/2/2013 50Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
or
1 1 d
dpr
pr g pc
pr pr T
zc c p
p z p
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Gas Isothermal Compressiblity Correlation by Matter, Brar & Aziz (1975)
2
1 0.27
1
pr
pr
r T
g
pr pr r
r T
dz
dc
p z T dz
z d
5/2/2013 51Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
4 2 2 4 2
1 2 3 4 8 8 82 5 2 1 exp
pr
r r r r r r
r T
dzT T T T A A A
d
3 521 1 2 43
5 6 73 4 53
;
0.27; ;
pr pr pr
pr
pr pr pr
A AAT A T A
T T T
pA A AT T T
T T T
A1 0.3150624 A5 -0.61232032
A2 -1.04671 A6 -0.10488813
A3 -0.578327 A7 0.68157001
A4 0.5353077 A8 0.68446549
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Gas Formation Volume Factor
,p T
g
sc
VB
V
By definition, the gas FVF is
Combining the above equation with the EOS yields
5/2/2013 52Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
30.02827 (ft /scf)
0.005035 (bbl/scf)
g
g
zTB
p
zTB
p
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Gas Viscosity Correlation Method by Carr, Kobayashi and Burrows (1954)
Step 1: Calculate pseudo-critical properties and the corrections to these properties for the presence of nonhydrocarbon gases (CO2, H2S, N2)
5/2/2013 53Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Step 2: Obtain the (corrected) viscosity of the gas mixture at one atmosphere and the temperature of interest
2 2 21 1uc N CO H S
Step 3: Calculate the pseudo-reduced pressure and temperature, and obtain the viscosity ratio (g/1)
Step 4: Calculate the gas viscosity from 1 and the viscosity ratio (g/1)
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Carr’s Atmospheric Gas Viscosity Correlation
5/2/2013 54Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Gas Viscosity Ratio Correlation
5/2/2013 55Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Standing’s Correlation for Atmospheric Gas Viscosity
5 6
1
3 3
1.709 10 2.062 10 460
8.118 10 6.15 10 log
uc g
g
T
5/2/2013 56Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
2 2
2 2
2 2
3 3
3 3
3 3
9.08 10 log 6.24 10
8.48 10 log( ) 9.59 10
8.49 10 log( ) 3.73 10
CO CO g
N N g
H S H S g
y
y
y
2 2 21 1uc CO N H S
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Dempsey’s Correlation for Gas Viscosity Ratio
2 3
0 1 2 3
1
2 3
4 5 6 7
2 2 3
8 9 10 11
3 2 3
12 13 14 15
lng
pr pr pr pr
pr pr pr pr
pr pr pr pr
pr pr pr pr
T a a p a p a p
T a a p a p a p
T a a p a p a p
T a a p a p a p
5/2/2013 57Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
a0 = −2.46211820a1 = 2.970547414 a2 = −2.86264054 (10−1) a3 = 8.05420522 (10−3) a4 = 2.80860949 a5 = −3.49803305a6 = 3.60373020 (10−1)a7 = −1.044324 (10−2)a8 = −7.93385648 (10−1)a9 = 1.39643306a10 = −1.49144925 (10−1)a11 = 4.41015512 (10−3)a12 = 8.39387178 (10−2)a13 = −1.86408848 (10−1)a14 = 2.03367881 (10−2)a15 = −6.09579263 (10−4)
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Exercise 4
A gas well is producing at a rate of 15,000 ft3/day from a gas reservoir at an average pressure of 2,000 psia and a temperature of 120°F. The specificgravity is 0.72.
Calculate the vicosity of the gas mixture using both graphical and analytical methods.
5/2/2013 58Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Properties of Crude Oil
5/2/2013 59Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Oil density and gravity
Gas solubility
Bubble-point pressure
Oil formation volume factor
Isothermal compressibility coefficient of
undersaturated crude oils
Oil viscosity
These fluid properties are usually determined by laboratory experiments. When such experiments are not available, empirical correlations are used
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Crude Oil Density
5/2/2013 60Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The crude oil density is defined as the mass of a unit volume of the crude oil at a specified pressure and temperature.
3 (lb/ft )oo
o
m
V
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Crude Oil Gravity
5/2/2013 61Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The specific gravity of a crude oil is defined as the ratio of the density of the oil to that of water.
oAPI is usually used to reprensent the gravity of the crude oil as follow
3; 62.4 (lb/ft )oo w
w
141.5-131.5o
o
API
The API gravity of crude oils usually ranges from 47° API for the lighter crude oils to 10° API for the heavier crude oils.
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Black Oil Model
5/2/2013 62Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Gas Solubility Rs
5/2/2013 63Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Rs is defined as the number of standard cubic feet of gas dissolved in one stock-tank barrel of crude oil at certain pressure and temperature.
The solubility of a natural gas in a crude oil is astrong function of the pressure, temperature, API gravity, and gas gravity.
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Gas Solubility Rs
5/2/2013 64Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Standing’s Correlation for Rs
5/2/2013 65Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
1.2048
1.4 1018.2
0.0125 0.0009 460
x
s g
pR
x API T
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Characteristics of Reservoir Rocks
5/2/2013 66Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Porosity
Permeability
In-situ Saturation
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pore bulk matrix
bulk bulk
V V V
V V
Porosity
5/2/2013 67Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Porosity
Porosity depends on grain packing, NOT grain size
Rocks with different grain sizes can have the same porosity
• Rhombohedral packing
• Pore space = 26 % of total volume• Cubic packing
• Pore space = 47 % of total volume
5/2/2013 68Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Rock Matrix and Pore Space
Rock matrix Pore space
5/2/2013 69Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Pore-Space Classification
Total porosity
Effective porosity
Total Pore Space
Bulk Volume
pore
t
bulk
V
V
Interconnected Pore Space
Bulk Volumee
5/2/2013 70Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Permeability is a property of the porous
medium and is a measure of the capacity of
the medium to transmit fluids
Permeability
5/2/2013 71Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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When the medium is completely saturated
with one fluid, then the permeability
measurement is often referred to as specific
or absolute permeability
Absolute Permeability
5/2/2013 72Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Effective permeability is a measure of the
fluid conductance capacity of a porous
medium to a particular fluid when the
medium is saturated with more than one
fluid
Effective Permeability
5/2/2013 73Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Relative permeability is defined as the ratio
of the effective permeability to a fluid at a
given saturation to the effective permeability
to that fluid at 100% saturation
Relative Permeability
5/2/2013 74Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil
Water
Gas
k
kk eo
ro
k
kk ew
rw
k
kk
egrg
Calculating Relative Permeabilities
5/2/2013 75Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Darcy’s Law
v: Velocity
q: Flow rate
A: Cross-section area
k: Permeability
: Viscosity
L: Length increment
p: Pressure drop
q
Direction of flowA
q k pv
A L
5/2/2013 76Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Fluid Saturation
Fluid saturation is defined as the fraction of pore volume occupied by a given fluid
Phase saturations
Sw = water saturation
So = oil saturation
Sg = gas saturation
specific fluid
pore
SaturationV
V
5/2/2013 77Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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In-Situ Saturation
Rock matrix Water Oil and/or gas
5/2/2013 78Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Exercise 5
1. Pore volume occuppied by water
2. Pore volume occupied by hydrocarbon
5/2/2013 79Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Given the following reservoir data:
Bulk Volume Vb
Porosity
Water saturation Sw
Calculate:
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Reservoir Drive Mechanisms
Solution Gas Drive
Gas Cap Drive
Water Drive
Gravity drainage drive
Combination drive
5/2/2013 80Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Reservoir Energy Sources
Liberation, expansion of solution gas
Influx of aquifer water
Expansion of reservoir rock
Expansion of original reservoir fluids
Free gas
Connate water
Oil
Gravitational forces
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Solution-Gas Drive in Oil Reservoirs
Oil
A. Original Condition
B. 50% Depleted
Oil producing
wells
Oil producing
wells
5/2/2013 82Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Solution-Gas Drive in Oil ReservoirsFormation of a Secondary Gas Cap
Wellbore
Secondarygas cap
5/2/2013 83Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil producing well
Oilzone
OilzoneGas cap
Gas-Cap Drive in Oil Reservoirs
5/2/2013 84Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil producing well
Water Water
Cross Section
Oil Zone
Water Drive in Oil ReservoirsEdgewater Drive
5/2/2013 85Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil producing well
Cross Section
Oil Zone
Water
Water Drive in Oil Reservoirs Bottomwater Drive
5/2/2013 86Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Gravity Drainage Drive in Oil Reservoirs
Oil
Oil
Oil
Point A
Point B
Point C
Gas
Gas
Gas
5/2/2013 87Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Combination Drive in Oil Reservoirs
Water
Cross Section
Oil zone
Gas cap
5/2/2013 88Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Pressure and Gas/Oil Ratio Trends
0 20 40 60 80 100
100
80
60
40
20
0
Gas-cap drive
Water drive
Solution
-gas drive
Reservo
ir p
ressu
re,
Percen
t o
f o
rig
inal
Cumulative oil produced, percent of original oil in place
5/2/2013 89Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Exercise 6
1. How can we identify different reservoir drive
mechanisms?
2. Rank in descending order typical reservoir drive
mechanisms in terms of efficiency
3. How does knowledge about reservoir drive mechanisms
help us in designing an oil field development plan?
5/2/2013 90Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Material Balance Equation (MBE)
5/2/2013 91Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
An Overview of MBE
Generalized Material Balance Equation
MBE for Typical Oil and Gas Reservoirs
Applications of MBE
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An Overview of MBE
5/2/2013 92Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
First developed by Schilthuis in 1936, MBE is
considered to be a tool for:
estimating initial hydrocarbon in place
predicting future reservoir performance
predicting ultimate reservoir recovery
under certain type of driving mechanisms
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Fundamentals of MBE
5/2/2013 93Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
MBE is derived using the following assumptions:
Reservoir
Bulk
Volume
Volume of
Rock Matrix
Pore
VolumeConstant
The pore volume is fully occuppied by existing fluid components (oil, gas, water)
The reservoir is homogenuous and isotropic (zero-dimensional)
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General MBE (GMBE)
5/2/2013 94Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
GMBE is an MBE that can be applied to
all reservoir types;
MBE for a particular type of reservoir
can be derived from the GMBE by
removing nonexistent terms.
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Tank Model
5/2/2013 95Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
INITIAL OIL
INITIAL GAS-CAP GAS
REMAINING OIL
CURRENT GAS-CAP GAS
RELEASED GAS
INJECTED GAS
NET WATER INFLUX
EXPANDING CONATE WATER
EXPANDING ROCK MATRIX
INJECTED WATER
Initial Condition Current Condition
ROCK (MATRIX)
CONATE WATER
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Derivation of GMBE
5/2/2013 96Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Volume ofInitial Oil
Volume of Initial Gas Cap
Volume of Remaining Oil
Volume of Expanding Rock Matrix
Volume of Remaining Free Gas
Volume ofWater Influx
Volume ofRock Matrix
Volume of Conate Water
Volume ofExpanding
Conate Water
Volume ofInjectedWater
Volume of Injected Gas
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Acronyms in GMBE
5/2/2013 97Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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GMBE: Final Formulation
5/2/2013 98Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
( ) ( ) (1 )1
( )
w wi ftit ti g gi ti e inj w inj g
gi wi
p t p si g p w
c S cNmBN B B B B m NB p W W B G B
B S
N B R R B W B
( )t o si s gB B R R B
ti oiB B
Where:
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Exercise 7
1. Derive the equation for the pore volume of the reservoir
2. Derive the equations for water and rock matrix
expansions
3. Derive the equation for the initial gas in the reservoir
4. Derive the equation for the remaining free gas in the
reservoir
5/2/2013 99Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Fluid Flows in Reservoirs
5/2/2013 100Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Properties of Reservoir Fluids in Motion
Flow Regimes
Flow Geometry
Fluid Flow Equations
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Properties of Reservoir Fluids
5/2/2013 101Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Classification Criteria: Isothermal Compressibility
or
Slightly Compressible Fluids
Reservoir Fluids
Incompressible Fluids
Compressible Fluids
dp
dV
Vc
1
dp
dc
1
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Incompressible Fluids
5/2/2013 102Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Volume and density do not change with pressure
0; 0 0l
Vc
p p
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Slightly Compressible Fluids
5/2/2013 103Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Small changes in volume or density with changes in pressure
ppc
refrefeVV
!!2!11
21
n
xxxe
nx For small x: xex 1
ppcVV refref 1
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Slightly Compressible Fluids
5/2/2013 104Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
refo
o
oppc
BB
ref
1
refooo ppcref
1
![Page 105: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/105.jpg)
Compressible Fluids
5/2/2013 105Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
A compressible fluid has compressibility ranging from 1.E-3 to 1.E-4
1 1g
zc
p z p
g
pM
zRT
gsc scg
c g c sc
p zB T
T p
![Page 106: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/106.jpg)
Flow Regimes
5/2/2013 106Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Classification Criteria: Changes in pressure with time
Pseudosteady-State Flow
Flow Regimes
Steady-State Flow
Unsteady-State Flow
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Steady-State Flows
5/2/2013 107Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Pressure does not change with time
0
t
p
![Page 108: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/108.jpg)
Unsteady-State Flows
5/2/2013 108Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Pressure derivative with respect to time is a function of both space and time
),( tft
px
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Pseudo-Steady Flows
5/2/2013 109Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Pressure declines with a constant rate
const.
t
p
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Flow Geometry
5/2/2013 110Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The shape and boundaries of a reservoir has a significant effect on its flow geometry.
Linear Flow
Flow Geometry
Radial Flow
Hemispherical Flow Spherical Flow
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Radial Flow
5/2/2013 111Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Fluids move toward the well from all directions
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Linear Flow
5/2/2013 112Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Flow paths are parallel and the fluid flows in a single direction
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Spherical Flow
5/2/2013 113Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
A well with a limited perforated interval could result in spherical flow in the vicinity of the perforations
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Hemispherical Flow
5/2/2013 114Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
A well which only partially penetrates the pay zone coud result in hemispherical flow
Wellbore
Flow lines
Side view
![Page 115: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/115.jpg)
Fluid Flow Equations
5/2/2013 115Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Describing the flow behavior in a reservoir
Depending on the combination of variables
recently presented (types of fluids, flow regimes, …)
Developed by combining Darcy’s transport
equation with the conservation of mass and various
equations of state
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Darcy Law
5/2/2013 116Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Velocity of a homogeneous fluid in a porous medium is proportional to the pressure gradient, and inversely proportinoal to the fluid viscosity.For a radial flow system, Darcy’s transport equation is given by
r
pk
A
qv
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Pseudo-Steady State Radial Flow of Slightly Compressible Fluids
5/2/2013 117Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
75.0ln
00708.0
w
eo
wfr
o
r
rB
ppkhQ
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Pseudo-Steady State Radial Flow of Compressible Fluids
5/2/2013 118Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
75.0ln1422w
e
wfr
g
r
rT
pmpmkhQ
p
dpZ
ppm
0
2)(
Where the real-gas pseudo pressure m(p) is defined as:
For 2000 ≤ pwf ≤ 3000 psi:
![Page 119: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/119.jpg)
Pressure Squared Approximation for Compressible Fluid Flow Equations
5/2/2013 119Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
75.0ln1422
22
w
e
r
g
r
rZT
ppkhQ
wf
2
22
wfr
avg
ppp
For pwf<2000 psi:
and are determined at the average pressure
Zavgp
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Average Pressure Approximation for Compressible Fluid Flow Equations
5/2/2013 120Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
75.0ln1422w
egg
r
g
r
rBT
ppkhQ
wf
2
wfr
avg
ppp
For pwf>3000 psi:
Average Z, g are calculated at the average pressurepavg.
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Exercise 8
5/2/2013 121Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The PVT data from a gas well in the Anaconda Gas Field is given below:
p (psi) mu (cp) Z
0.0 0.01270 1.000
400.0 0.01286 0.937
800.0 0.01390 0.882
1200.0 0.01530 0.832
1600.0 0.01680 0.794
2000.0 0.01840 0.770
2400.0 0.02010 0.763
2800.0 0.02170 0.775
3200.0 0.02340 0.797
3600.0 0.02500 0.827
4000.0 0.02660 0.860
4400.0 0.02831 0.896
The well is producing at a stabilized
bottom-hole flowing pressure of 2800
psi. The wellbore radius is 0.3 ft. The
following additional data is available:
k=65 md, h=15 ft, T=600 °R,
Pr = 4400 psi, re=1000 ft,
1. Calculate the gas flow rate in
Mscf/day
2. Draw the graph of m(p) vs p
![Page 122: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/122.jpg)
Numerical Integration
5/2/2013 122Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Trapezoidal Method
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Constant-Termial-Rate Solution
5/2/2013 123Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
kt
rcEi
kh
qBpp t
i
29486.70
![Page 124: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/124.jpg)
Exponential Integral
5/2/2013 124Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
duu
exEi
x
u
)(
![Page 125: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/125.jpg)
Approximation of Ei Function
5/2/2013 125Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
2 3 2 3 81 2 3 4 5 6 7
1
2
2
3
3
4
5
6
2
7
0.01
( ) ln(1.781 )
0.01 3.0
( ) ln( ) [ln( )] [ln( )]
0.33153973
0.81512322
5.22123384 10
5.9849819 10
0.662318450
0.12333524
1.0832566 10
x
Ei x x
x
aEi x a a x a x a x a x a x a x
x
a
a
a
a
a
a
a
a
4
8 8.6709776 10
![Page 126: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/126.jpg)
Exercise 9
5/2/2013 126Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
An oil well is producing at a constant flow rate of 300 STB/day under unsteady-
state flow conditions. The reservoir has the following rock and fluid properties
Bo=1.25 bbl/STB, =1.5cp, ct=12 x 10-6 psi-1
ko=60 md, h=15 ft, pi=4000 psi,
= 15%, rw=0.25 ft,
1. Calculate the pressure at radii of 0.25, 5, 10, 50, 100, 500, 1000, 1500,
2000, and 2500 ft, for 1 hour. Plot the results as:
• pressure versus the logarithm of radius
• pressure versus radius
2. Repeat question 1 for t=12 hours and 24 hours. Plot the results as
pressure versus logarithm of radius
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Part III
5/2/2013 127Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Data Analysis Methods In
Reservoir Engineering
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Overview of Data Analysis in Reservoir Engineering
5/2/2013 128Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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PVT Analysis
5/2/2013 129Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The objective of PVT Analysis is to
estimate essential properties and
predict behaviors of reservoir fluids
during production
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PVT Analysis Tools
5/2/2013 130Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Wax & Asphaltene Deposition
PVT ANALYSIS
SAMPLING SPECIAL STUDYGAS CONDENSATEBLACK OIL
Effect of Injection Gas on Fluid Properties
Quality check
Effect of Injection Chemical on Fluid
Properties
Compositional analysis
Constant Composition Expansion
Viscosity Test
Quality check
Separator Test
Differential Vaporisation Test
Subsurface
Open hole
Case hole
Surface
Separator
WellheadCompositional
analysis
Constant composition expansion
Quality check
Constant Volume Depletion
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Basic PVT Data for Black Oil
5/2/2013 131Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil Formation Volume Factor
5/2/2013 132Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Solution Gas Oil Ratio
5/2/2013 133Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil Viscosity
5/2/2013 134Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil Formation Volume Factor
Oil Formation Volume Factor at 200 F
1.000
1.100
1.200
1.300
1.400
1.500
1.600
0 1000 2000 3000 4000 5000
Pressure, psig
Oil F
orm
ati
on
Vo
lum
e F
acto
r b
bl/stb
Above bubble point pressure, Bo increases as pressure decreases. Why?
Below bubble point pressure, Bo decreases as pressure decreases. Why?
5/2/2013 135Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Oil Density at 200 F
0.700
0.710
0.7200.730
0.740
0.750
0.760
0.7700.780
0.790
0.800
0.810
0.8200.830
0.840
0.850
0 1000 2000 3000 4000 5000
Pressure, psig
Oil D
en
sit
y,g
/cc
Oil Density
Above Pb, the oil density decreases. Why?
Below Pb, the oil density increase. Why?
The reduction of mass is minimal compare to oil volume decrease
5/2/2013 136Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Solution Gas Oil Ratio at 200 F
0
50
100
150
200
250
300
350
400
450
500
550
600
0 1000 2000 3000 4000 5000
Pressure, psig
So
luti
on
Gas O
il R
ati
on
scfl
/stb
Above bubble point pressure,Rs is constant. Why?
Below bubble point pressure,Rs decreases as pressuredecreases. Why?
It will continue to vapouriseuntil no gas come out fromthe oil at the atmosphericpressure.
Solution Gas Oil Ratio
5/2/2013 137Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
![Page 138: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/138.jpg)
Exercise 10
1. Explain why above the bubble point pressure (Pb), Bo
increases as pressure decreases whereas below Pb, Bo
decreases as pressure decreases.
2. Explain why above Pb, the oil density decreases as
pressure decreases whereas below Pb, it increases as
pressure decreases.
3. Explain why above Pb, Rs is constant whereas below Pb, it
decreases as pressure decreases.
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Well Test Analysis
5/2/2013 139Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
The objective of well test analysis is to
interprete data obtained from well tests
for the ultimate purpose of identifying
reservoir characteristics such as
dynamic pressure behavior in
reservoirs, permeability, reservoir
boundaries, wellbore storage, etc ...
![Page 140: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/140.jpg)
Wellbore Storage
5/2/2013 140Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Skin Factor - Formation Damage
5/2/2013 141Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Skin Factor
500
1000
1500
2000
1 10 100 1000 10000
Distance from center of wellbore, ft
Pre
ssu
re, p
si
s = +5
s = -2
s = 0
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Types of Well Tests
5/2/2013 143Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Drawdown Tests
Buildup Tests
Isochronal Tests
Modified Isochronal Tests
Inteference Tests
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Types of Well Tests
5/2/2013 144Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Types of Test
5/2/2013 145Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Types of Test
5/2/2013 146Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
![Page 147: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/147.jpg)
Type of Test
5/2/2013 147Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Interference Test
5/2/2013 148Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Diffusivity Equation
5/2/2013 149Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Well Test Analysis Techniques
MDH Analysis
Horner Analysis
Pressure Derivative Based Techniques
Type Curves Analysis
Numerical Simulation
5/2/2013 150Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Constant-Terminal-Rate Solution
294870.6 t
i
c rQBp p Ei
kh kt
![Page 152: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/152.jpg)
Log Approximation to the Ei-Function
2162.6 log 3.23 0.87wf i
t w
QB ktp p s
kh c r
bmxy
249.48 10 t wc r
tk
![Page 153: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/153.jpg)
Finite Acting Radial FlowMDH analysis
5/2/2013 153Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Problems with Drawdown Tests
It is difficult to produce a well at a strictly constant rate;
Even small variations in rate distort the pressure
response.
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Buildup Test - Pressure Response
ttp
t0
tp + t
0
![Page 156: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/156.jpg)
Buildup Test - Superposition
s869.023.3rc
klogtlog
kh
qB6.162
s869.023.3rc
klogttlog
kh
qB6.162pp
2wt
1010
2wt
10p10iws
![Page 157: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/157.jpg)
Pressure Response for a Buildup Test
10162.6 logp
ws i
t tqBp p
kh t
y = mx + b
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Finite Acting Radial FlowHorner analysis
5/2/2013 158Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Estimating Skin – Horner Plot
5/2/2013 159Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
1 0
21.1513 log 3.23
hr wf t
t w
p p ks
m c r
P1hr: Pressure after 1 hr shut-in
Pwf|t=0: Flowing well pressure immediately before shut-in
![Page 160: Basic Reservoir Engineering - Mai Cao Lan](https://reader035.fdocuments.in/reader035/viewer/2022081312/55cf9de2550346d033afad48/html5/thumbnails/160.jpg)
Type Curve Analysis: Data Set
5/2/2013 160Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Dimensionless Variable
5/2/2013 161Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
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Type Curve Analysis: Unmatched Overlay
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Type Curve Analysis: Matched in Pressure
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Type Curve Analysis: Matched in Both Pressure & Time
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Type Curve Analysis: Extraction of Type Parameters
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Pressure Match: Extracting kh
From the expression of dimensionless pressure
one defines the pressure match Mp
Mp is read as the value of pD matching a specific value of Δp. Then
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Skin Match: Extracting S
One reads the value of Ms on the matching type curve:
Then
with CD calculated from its dimensionless expression:
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Agarwal’s Type Curves
5/2/2013 168Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
First introduced by Agarwal et al. (1970), a type curve is a graphical representation of the theoretical solution to the flow equation with the following dimensionless groups:
pQB
khPD
2.141t
rc
kt
wt
D 2
0002637.0
w
Dr
rr
QB
khpPD
2.141log)log(log
22
0002637.0log)log(log
rc
kt
r
t
tD
D
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Type-Curve Methods
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Type-Curve Methods
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Gringarten’s Type Curves
5/2/2013 171Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Dimensionless groups for Drawdown Tests:
ddD pQB
khP
2.141t
C
kh
C
t
D
D
0002951.0
Dimensionless groups for Buildup Tests:
buD pQB
khP
2.141 e
D
D tC
kh
C
t
0002951.0
p
e
t
t
tt
1
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Gringarten’s Type Curves
5/2/2013 172Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
For the wellbore storage dominated period, the graph PD vs tD/CD is a unit-slope straight line:
1
D
D
D
D
DD
C
td
Pd
C
tP
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Gringarten’s Type Curves
5/2/2013 173Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
For the Infinite Acting Radial Flow period, one has:
s
D
D
DD eC
C
tP 2ln80907.0ln
2
1
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Bourdet’s Pressure Derivative
5/2/2013 174Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Bourdet et al. (1983) defined pressure derivative as:
D
D
DD
C
td
PdP '
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Bourdet’s Pressure Derivative Method
5/2/2013 175Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
For the wellbore storage dominated period, the graph PD vs tD/CD is a unit-slope straight line:
D
D
D
DDD
C
t
C
tPP
'' 1
xyWS
D
D
D
DDWS
C
tx
C
tPy
;'
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5/2/2013 176Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
For the Infinite Acting Radial Flow period, one has:
s
D
D
DD eC
C
tP 2ln80907.0ln
2
1
2
11
2
1 ''
D
DD
D
DD
C
tP
C
tP
2
1IARFy
Bourdet’s Pressure Derivative Method
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5/2/2013 177Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
Physical Pressure Derivative (using Finite Difference method):
11
11 )()('
ii
ii
t
dddd
tt
tptp
td
pdp
i
Bourdet’s Pressure Derivative
11
11)()(
'
ii
ii
ieee
ee
te
bubu
tt
tptp
td
pdp
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Exercise 11
Using the reservoir and welltest data to:
5/2/2013 178Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
DataParam Value Unit
0.25
ct 4.2E-06 psi
B 1.06 bbl/STB
rw 0.29 ft
2.5 cp
h 107 ft
Q 174 bbl/STB
tp 15 hrs
Draw p vs te graph in
log-log scale
Draw p’ vs te graph in
log-log scale
Calculate the wellbore
storage factors C and CD.
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Exercise 11 (cont’d)
5/2/2013 179Mai Cao Lân – Faculty of Geology & Petroleum Engineering - HCMUT
0 3086.330.00417 3090.570.00833 3093.81
0.0125 3096.550.01667 3100.030.02083 3103.27
0.025 3106.770.02917 3110.010.03333 3113.25
0.0375 3116.490.04583 3119.48
0.05 3122.48
0.0583 3128.960.06667 3135.92
0.075 3141.170.08333 3147.64
0.09583 3161.950.10833 3170.680.12083 3178.390.13333 3187.120.14583 3194.24
0.1625 3205.960.17917 3216.680.19583 3227.89
0.2125 3238.370.22917 3249.07
0.25 3261.790.29167 3287.210.33333 3310.15
0.375 3334.340.41667 3356.270.45833 3374.98
0.5 3394.440.54167 3413.90.58333 3433.83
0.625 3448.050.66667 3466.260.70833 3481.97
0.75 3493.690.8125 3518.63
0.875 3537.340.9375 3553.55
1 3571.751.0625 3586.23
1.125 3602.951.1875 3617.41
1.25 3631.151.3125 3640.86
1.375 3652.851.4375 3664.32
1.5 3673.811.625 3692.27
1.75 3705.521.875 3719.26
2 3732.232.25 3749.71
2.375 3757.192.5 3763.44
2.75 3774.653 3785.11
3.25 3794.063.5 3799.8
3.75 3809.54 3815.97
t Pws(hrs) (psi)
t Pws(hrs) (psi)
t Pws(hrs) (psi)
t Pws(hrs) (psi)
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The End
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GEOPET BACHELOR PROGRAM PETROLEUM ENGINEERING