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DESCRIPTION
FluidsTRANSCRIPT
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FLUIDSPresentation Agenda:
Composition of Hydrocarbon Fluids, Parameters and Measurements
Significance in Play/Prospect Evaluation
A Simplified Classification
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FLUIDS Commercial hydrocarbon fluids comprise a series of compounds of
hydrogen and carbon from simple methane gas (CH4) through to complex heavy oils (C15+).
The conventional twofold division of produced commercial hydrocarbon products into oil and gas is an artificial one based on the hydrocarbon state at surface conditions.
There exists in the subsurface a continuum of complex fluids between the two end members. At atmospheric conditions, dissolved gas is liberated from the oil and liquids condense out from the gas due to the drop in temperature and pressure.
The hydrocarbon series can be divided up into constituent parts by the use of the gas oil ratio (GOR) also known as the Gas Liquid Ratio (GLR). This ratio is in volume per volume at subsurface conditions, expressed as standard cubic feet of gas per barrel of oil (scf/bbl) or cubic metres of gas per cubic metre of oil (m3/m3).
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FLUIDS
GAS OILCOMPLEX FLUIDS
diphasicmonophasic
e.g. condensate
Gas hydrates (frozen methane)Non-commercial today
AT SUBSURFACE P/T CONDITIONSmonophasic
Bitumen Tar
Poor economy to non-commercial
Commercial Hydrocarbon Fluids
Liquids
Solids
transportable
Tanker
Pipeline transportable
Need nearbymarket
Gas difficult to store
Liquids easy to store
Hydrocarbons - a continuum of increasingly complex compounds of hydrogen and carbon, with many accessory components, including sulphides, CO2 and heavy metals.
Light Compounds Heavy compounds
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FLUIDSTypical Hydrocarbon P/T Phase Diagram
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FLUIDSTypical Fluid State Phase Diagrams - Oils
High energy system
Low energy system
Unsaturated Oil:
At the reservoir temperature the bubble pressure is less than the bottom hole pressure
Saturated Oil:
The bubble pressure is equal to the bottom hole pressure. The slightest fall in pressure results in two phase production
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FLUIDSTypical Fluid State Phase Diagrams - Gases
Condensate Gas:The bottom isotherm cuts the fluid dew point curve. Depletion results in deposition of condensate in the reservoir.
Wet Gas:The bottom isotherm is to the right of the cricondotherm and the surface conditions are in the two phase region. The gas gives rise to condensate on the surface under normal test conditions, but not in the reservoir.
Dry Gas:The bottom isotherm is to the right of the cricondotherm and the surface conditions are outside the two phase region. This fluid does not give rise to any surface condensate under normal test conditions, it is always possible to obtain liquid by processing this gas at low temperatures
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FluidsOil Density versus API Gravity
Oil Density vs API Gravity
05
101520253035404550556065
0.74
0.76
0.78
0.80
0.82
0.84
0.86
0.88
0.90
0.92
0.94
0.96
0.98
1.00
Density g/cc
Gra
vity
API
Very Heavy Oil
Heavy Oil
Normal Oil
Light Oil
Condensate
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FluidsFormation Pressure and Fluid Composition
PRESSURE vs GLR
250
300
350
400
450
500
10 100 1000 10000 100000GLR m3/m3
PRES
SUR
E ba
rs
No Complex Fluids at Lower Pressures
COMPLEX FLUIDOIL GAS
DIPHASIC
MONOPHASIC
NORMAL OIL LIGHT OIL CRITICAL FLUID CRITIQUE
GAS RICH IN CONDENSATE GAS CONDENSATEHEAVY OIL WET GAS
25API 43API 48API 57API APPROXIMATE API GRAVITY VALUES
52API39API
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FLUIDS - Distribution The distribution of hydrocarbon fluid types is
controlled by the geological evolution of Pressure/Temperature conditions during maturation migration accumulation retention leakage - recharging..
It is a complex subject and it is difficult to accurately predict the fluid composition of a prospect prior to drilling.
However, the position of a play in a petroleum system is frequently used to estimate the probable producible fluid:
Hot and deep = gas prone Shallow and low temperature = heavy oil Between, anything is possible!
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FLUIDS Oil Shrinkage Factor The oil shrinkage factor
(Bo) is used to convert calculated subsurface volumes to surface volumes (stock tank barrels) at standard temperature and pressure.
The shrinkage is due to the exsolution of dissolved gas.
Low GOR oils have low Bo values close to unity.
High GOR oils have high Bo values ~ 0.5
+
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FLUIDS Gas Expansion Factor
The gas expansion factor (Bg) is used to convert reservoir volumes to surface volumes (m3) at standard temperature and pressure.
Gas increases in volume from reservoir to surface due to decreased temperature and pressure.
This increase in volume very significant, e.g. at 3000m the Bg factor usually ranges from 250 to 300.
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FLUIDS Other Hydrocarbons
Other hydrocarbons that are generally uneconomic to exploit are:
Bitumen (Tar) e.g. Athabasca Tar sands, Canada. Gas hydrates Frozen Methane.
Neither resource can currently be extracted at commercially viable rates compared to conventional oil and gas.
Hence no further discussion here.
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FLUIDS Recovery Factor The recovery factor is the fraction of in-place oil
or gas that is producible, expressed as %. A great deal depends on the reservoir drive
mechanism and secondary and tertiary methods used to produce the fluids.
Gas is extremely mobile and purely by depletion/gas expansion, the resultant recovery will be high.
Oil is less mobile and subject to poorer recovery rates.
Hence the inclusion of fluid type as a criterion in Play and Prospect evaluation.
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FLUIDS Recovery Factor
Typical ranges of primary plus secondary recovery values:
OilSandstones 21 - 37 52%Carbonates 27 - 42 52%
GasSandstones 50 - 65 80%Carbonates 65 - 80 95%
But the drive mechanism plays a major role
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Resources Categories
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FLUIDS Primary Oil Recovery MechanismsSecondary and tertiary methods commonly used to improve recovery efficiencye.g. gas lift, water injection, miscible gas injection.
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FLUIDS Primary Oil Recovery MechanismsNatural Depletion Drive:
Low recovery efficiency
Small traps, low GOR oil
Little to no aquifer support
Bulk of oil production early on
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FLUIDS Primary Oil Recovery Mechanisms
Solution Gas Drive: Isolated traps, moderate GOR oil
Low to moderate recovery efficiency
Little to no aquifer support
Bulk of oil production early on, then gas with slow decline.
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FLUIDS Primary Oil Recovery Mechanisms
Gas Cap Drive: Saturated oil in a trap with a free gas cap
Moderate recovery efficiency
Little to no water drive
Bulk of oil production early on, then gas slowly building.
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FLUIDS Primary Oil Recovery MechanismsNatural Water Drive:
Under-saturated oil in a trap with a regionally extensive reservoir
Good to excellent recovery efficiency
Large aquifer
Reservoir heterogeneity converts bottom to edge drive
Long oil production plateau period, gas production fairly constant, water rises severely towards end.
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FLUIDS Primary Oil Recovery MechanismsCompaction Drive:
Under-saturated and heavy oil in an isolated trap at shallow burial depths
Poor to moderate recovery efficiency
Little to no aquifer
Reservoir unconsolidated
Very slow oil production decline.
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FLUIDS Primary Oil Recovery MechanismsGravity Drive:
Under-saturated and heavy oil in high structural relief trap
Poor to moderate recovery efficiency
Little to no aquifer
Reservoir with great lateral continuity
Bulk of oil production early on, then gas building at end.
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FLUIDS Gas Recovery Mechanisms
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FLUIDS Gas Recovery MechanismsNatural Depletion Drive:
Good to excellent recovery efficiency
Isolated traps, low GCR dry gas or wet gas
Little to no aquifer support
Gas production maintained at constant rate through export line (contract for sales)
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FLUIDS Gas Recovery MechanismsGas Recycling:
Good to excellent recovery efficiency
Isolated traps, high GCR wet gas with condensate
Little to no aquifer support
Inject dry gas to increase condensate recovery.
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FLUIDSA Simplified Classification
Franais CODE EnglishHUILE: normale, lourde. FO OIL: normal, heavy.GAZ: gaz sec, ,gaz humide, gaz condensat. FG GAS: dry gas, wet gas,gas-condensateFLUIDE COMPLEXE: gaz riche en condensat, fluide critique, huile lgre. FC
COMPLEX FLUID: gas rich in condensate, critical fluid, light oil.
BITUME FB BITUMEN: tarHYDRATE FH GAS HYDRATES
HYDROCARBON FLUIDS GOR/GLR RELATIONSHIPS
1
10
100
1000
10000
100000
1000000
10000000
1 10 100 1000 10000 100000 1000000
GLR m^3/m^3
GO
R s
cf/b
bl
Normal Oil
Dry Gas
Wet Gas
Gas - Condensate
Gas rich in Condensate
Critical Fluid
Light Oil
Heavy Oil
Dead Oil
COMPLEX FLUIDS
GAS
OIL
GA
Z
FLU
IDE
CO
MPL
EXE
HU
ILE
Gaz
sec
Gaz
c
onde
nsat
Gaz
hum
ide
Gaz
rich
e en
co
nden
sat
Flui
de C
ritiq
ue
Hui
le E
xtra
Lo
urde
Hui
le L
gr
e
Hui
le M
orte
Very Heavy Oil
Hui
le L
ourd
e
Hui
le N
orm
ale
39API
48API
25API
52API
57API
43API
10API
Valeurs de gravit approximatives
3 PRINCIPAL TYPES OF FLUID ( 2 SUPPLEMENTARY TYPES)
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FLUIDS CLASSIFICATIONHYDROCARBON FLUIDS GOR/GLR RELATIONSHIPS
1
10
100
1000
10000
100000
1000000
10000000
1 10 100 1000 10000 100000 1000000
GLR m^3/m^3
GO
R s
cf/b
bl
Normal Oil
Dry Gas
Wet Gas
Gas - Condensate
Gas rich in Condensate
Critical Fluid
Light Oil
Heavy Oil
Dead Oil
COMPLEX
FLUIDS
GAS
OIL
GA
Z
FLU
IDE
CO
MPL
EXE
HU
ILE
Gaz
sec
Gaz
c
onde
nsat
Gaz
hum
ide
Gaz
rich
e en
cond
ensa
t
Flui
de C
ritiq
ue
Hui
le E
xtra
Lour
de
Hui
le L
gr
e
Hui
le M
orte
Very Heavy Oil
Hui
le L
ourd
e
Hui
le N
orm
ale
39API
48API
25API
52API
57API
43API
10API
Valeurs de gravit
approximatives
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FLUIDS
FLUIDSFLUIDSFLUIDSFLUIDSFLUIDSFLUIDSFluidsFluidsFLUIDS - DistributionFLUIDS Oil Shrinkage FactorFLUIDS Gas Expansion FactorFLUIDS Other HydrocarbonsFLUIDS Recovery FactorFLUIDS Recovery FactorResources CategoriesFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Primary Oil Recovery MechanismsFLUIDS Gas Recovery MechanismsFLUIDS Gas Recovery MechanismsFLUIDS Gas Recovery MechanismsFLUIDSFLUIDS CLASSIFICATIONFLUIDS