Classification Of Petroleum Reservoir .pdf

Reservoir Engineering
Classifications Of Petroleum Reservoirs
By
Abbas Radhi Abbas
Iraq / Missan / 2022
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Classifications Of Petroleum Reservoirs ---- By : Abbas Radhi Abbas - Iraq / Missan / 2022

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1-According Nature of rock:
2-According to Technology
3-According to Reservoir boundary
4-According Geologic complexity
5-According to Reservoir dip
6-According Rock characteristics
7-According to Mode of production:
8-According to Location

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9-According to Reservoir pressure:
10-According to Production characteristics:
11-According to Reservoir life
12-According to fluid properties
13-According to Rock type
14-According to phase behavior
15-According to drive mechanism

1. Source rock : (petroleum is produced from where it was
generated)
2. Reservoir rock (oil and gas migrated to a separate location
from the source rock
1. Conventional – reservoirs that are developed and produced by
traditional tools and techniques; rock and fluid characteristics are
favorable for production on a commercial scale
2. Unconventional – reservoirs that require innovative approaches and
emerging technologies to develop economically due to unfavorable
conditions; unconventional reservoirs are characterized by ultratight
formation, extra heavy oil, or location of the reservoir at great depths,
among others
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According Nature of rock:
According to Technology

1. Closed
2. Edge-water drive
3. Bottom-water drive
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According to Reservoir boundary
Edge-water drive
Bottom-water drive

1. Single layered
2. Multilayered or stratified (communicating, partially communicating,
noncommunicating)
3. Fractured
4. Faulted (sealing, partially sealing, nonsealing)
5. Compartmental
6. Tight (poor oil and gas conductivity characteristics)
7. Highly heterogeneous (rock properties vary significantly)
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According Geologic complexity
1. Steep inclination – dictates location of wells
According to Reservoir dip

1. Unconsolidated
2. Consolidated
3. Tight
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According Rock characteristics
1. Primary (production by natural reservoir energy)
2. Secondary (production augmented by water flooding)
3. Tertiary (production enhanced by injecting chemical, foam, and
thermal treatment
According to Mode of production:

1. Onshore
2. Offshore, including deep-sea reservoirs
3. Shallow, including oil sands
4. Deep, including basin-centered reservoirs
1. Over-pressured
2. Under-pressured
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According to Location
According to Reservoir pressure:

1. Early stage in production
2. Peak production
3. Declining production
4. Matured reservoir)
1. Single-phase flow (oil or gas)
2. Multiphase flow (oil and gas, oil and water, oil, gas and water, gas
and water)
3. High water cut
4. High gas/oil ratio
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According to Production characteristics:
According to Reservoir life

1. Sandstone
2. Carbonate
3. Shale, silt, clay
4. Coalbed
5. Salt dome
6. Combinations of the above
1. Black oil
2. Volatile Oil
3. Retrograde condensate gas
4. Wet gas
5. Dry gas
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According to fluid properties
According to Rock type

1. Solution gas drive
2. Gas Cup drive
3. Water drive
4. Gravity drainage drive
5. Combination drive
1. Single phase gas
2. Gas condensate
3. Under saturated oil
4. saturated oil
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According to phase behavior
According to drive mechanism

•The Five Reservoir Fluids
1-According to fluid properties
According to fluid properties
1. Black oil
2. Volatile Oil
3. Retrograde condensate gas
4. Wet gas
5. Dry gas
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Black Oil Reservoirs:
•GOR < 1,000 SCF/STB
•Density less than 45° API
•Reservoir temperatures < 250°F
•Oil FVF < 2.00 (low shrinkage
oils)
•Dark green to black in color
•C7+ composition > 30%
Black Oil Reservoirs:
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Volatile Oil Reservoirs:
•1,000 < GOR < 8,000 SCF/STB
•Density between 45-60° API
•Oil FVF > 2.00 (high shrinkage
oils)
•Light brown to green in color
•C7+ composition > 12.5%
Volatile Oil Reservoirs:
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Gas Condensate Reservoirs:
•70,000 < GOR < 100,000
SCF/STB
•Density greater than 60° API
•Light in colour
•C7+ composition < 12.5%
Gas Condensate Reservoirs:
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Wet Gas Reservoirs:
•GOR > 100,000 SCF/STB
•No liquid is formed in the reservoir.
•Separator conditions lie within
phase envelope and liquid is
produced at surface.
Wet Gas Reservoirs:
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Dry Gas Reservoirs:
•GOR > 100,000 SCF/STB
•No liquid produced at surface
Dry Gas Reservoirs:
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Range of Reservoir fluid properties
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1. Clastic Reservoir
2. Carbonate Reservoir
According to Rock type
1-Clastic Reservoir
• Consist primarily of Silicate Mineral ( Quartz SiO2)
• Sandstone porosity ( 10-30 )%
2-Carbonate Reservoir
• Mean limestone and dolomite
• Limestone is better than dolomite for ( porosity and permeability )
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According to phase behavior
1. Single phase gas
2. Gas condensate
3. Under saturated oil
4. saturated oil
3-According to phase behavior
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Pressure-temperature phase diagram
for
multicomponent hydrocarbon reservoir
fluid mixture. For
isothermal production in the reservoir:
position A indicates
reservoir fluid found as an under
saturated oil;
position B
indicates reservoir fluid found as a gas
condensate;
position C indicates reservoir fluid
found as a dry gas
Pressure-temperature phase diagram
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4-According to drive mechanism
According to drive mechanism
1. Solution gas drive
2. Gas Cup drive
3. Water drive
4. Gravity drainage drive
5. Combination drive
Drive Mechanism
The natural energy of the reservoir used to transport hydrocarbons towards and out of the
production wells
.
There are five important drive mechanisms (or combinations).
1. Solution Gas Drive.
2. Gas Cap Drive.
3. Water Drive.
4. Gravity Drainage.
5. Combination or Mixed Drive
A combination or mixed drive occurs when any of the first three drives operate together
or when any of the first three drives operate with the aid of gravity drainage.
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1- Solution Gas Drive
Solution Gas Drive:
Gas breaks out of solution and
expanding gas maintains pressure
in reservoir somewhat over time
Trend
Characteristics
Declines rapidly and continuously
Reservoir Pressure
then drops
First low then rises to a maximum and
Gas/Oil Ratio
continues to decline First high, then decreases rapidly and
Production Rate
None
Requires artificial lift at early stages
Well Behavior
5-30% of original oil-in-place
Expected Oil Recovery
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Gas Cap Drive:
Gas in gas cap is expanding as pressure
depletes, maintaining pressure somewhat
overtime (later stages of solution gas drive)
2.Gas cap Drive.
Trend
Characteristics
Falls slowly and continuously
Reservoir Pressure
Rises continuously
Gas/Oil Ratio
First high, then declines gradually
Production Rate
Absent or negligible
Long flowing life depending on size of gas cap
Well Behavior Cap
20 to 40% of original oil-in-place
Expected Oil
Recovery
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Water Drive
Large aquifer volume expands
providing pressure for relatively
small oil volume. Can be
supplemented with water injection.
Over time:
3.Water Drive.
Trend
Characteristics
Remains high
Reservoir Pressure
Remains steady
Gas/Oil Ratio
tarts early and increases to appreciable amounts
Flow until water production gets excessive
Well Behavior Cap
up to 60% original oil-in-place.
Expected Oil
Recovery
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Gravity Drainage Drive
Usually for heavy oils with very little or no
gas.
Oil literally is produced as the density of the
oil drops and oil moves under force of
gravity.
Normally accompanied by artificial lift.
Can also be supplemented with water
injection.
Over Time:
Reservoir pressure remains low.
GOR very low if at all.
4.Gravity Drainage.
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combination drives : we have a gas cap
with the oil accumulation underlain
by water providing potential water drive
.So both free gas and water are in
contact with the oil.
In such a reservoir some of the energy
will come from the expansion of the gas
and some from the energy within the
massive supporting aquifer and it is
associated compressibility.
5.Combination or Mixed Drive
5.Combination or Mixed Drive
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About Authorized
Name: Abbas Radhi Abbas
Position: Chief Engineer / petroleum Engineer
Nationality: Iraq- Missan
Date of Birth: 1978
Gender: Male
Education Background:
Period Education description
1996-2001 University of Bagdad – college of Engineering – petroleum engineering department- (BSc)
Certificates of Appreciation
• 15 Certificates of Appreciation from different international companies such as (Schlumberger-
Halliburton Weatherford , CNOOC , COSL , BHDC )
• 17 online webinar during 2020-2022
Work Experience : in Missan Oil Company ( MOC)
Period Work description
(2004-2006) reservoir engineer
(2006-2010 ) water injection engineer
during (2011) drilling and workover engineer
(2011 to 2022 ) petrophysics manager in Geology and Reservoir department
Language:
Mother language: Arabic
Second
language/level:
English/Fluent oral and written in English.

Thank You!
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Classification Of Petroleum Reservoir .pdf

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Classification Of Petroleum Reservoir .pdf