Hydrocarbon Reservoir System Hydrocarbon Reservoir System (Basic Approach for Non Petroleum People) (Basic Approach for Non Petroleum People) PREPARED BY D.MULYONO (PETROLEUM ENGINEER) SERIES OF CONTINUOUS LESSON & LEARN FOR IFF DUKHAN COMMUNITY JUNE 23 RD 2012
107
Embed
Basic Hydrocarbon Reservoir System - … and gas are formed by the thermal cracking of organic compounds buried in fine-grained rocks. ... hydrocarbon system, the reservoir ...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Hydrocarbon Reservoir SystemHydrocarbon Reservoir System(Basic Approach for Non Petroleum People)(Basic Approach for Non Petroleum People)
P R E P A R E D B Y D . M U L Y O N O ( P E T R O L E U M E N G I N E E R )S E R I E S O F C O N T I N U O U S L E S S O N & L E A R N F O R I F F
D U K H A N C O M M U N I T YJ U N E 2 3 R D 2 0 1 2
Basic elements of Petroleum Systems Describe plate tectonics and sedimentary basins Recognize names of major sedimentary rock types Describe importance of sedimentary environments to petroleum
industry Describe the origin of petroleum Identify hydrocarbon trap types Define and describe the important geologic controls on reservoir
properties, porosity and permeability
Objectives for the participants (at least…..)knowing & if possible having interestTo know further the topics of :
Basic elements of Petroleum Systems Describe plate tectonics and sedimentary basins Recognize names of major sedimentary rock types Describe importance of sedimentary environments to petroleum
industry Describe the origin of petroleum Identify hydrocarbon trap types Define and describe the important geologic controls on reservoir
properties, porosity and permeability
• Petroleum Systems approach• Geologic Principles and geologic time• Rock and minerals, rock cycle, reservoir properties• Hydrocarbon origin, migration and accumulation• Sedimentary environments and facies; stratigraphic
• Petroleum Systems approach• Geologic Principles and geologic time• Rock and minerals, rock cycle, reservoir properties• Hydrocarbon origin, migration and accumulation• Sedimentary environments and facies; stratigraphic
natural gase(up to 97% of methane; ethane,propane, CO2, N2)
petroleum(mixture of aliphatic, alicyclic, andpolycyclichydrocarbons C1-C50; thecomposition varies with its
location).
What is Hydrocarbon……?
fractions of petroleum: gas (C1-C4) ~ cooking gas
petroleum ether (C5-C6) ~solvent for org. chemicals
gasoline (C6-C12) ~ automobilefuel
kerosene (C11-C16) ~ rocketand jet fuel
fuel oil (C14-C18) ~ domesticheating
lubricating oil (C15-C24) ~lubricants for automobiles andmachines
Main natural source:
natural gase(up to 97% of methane; ethane,propane, CO2, N2)
petroleum(mixture of aliphatic, alicyclic, andpolycyclichydrocarbons C1-C50; thecomposition varies with its
location).
fractions of petroleum: gas (C1-C4) ~ cooking gas
petroleum ether (C5-C6) ~solvent for org. chemicals
gasoline (C6-C12) ~ automobilefuel
kerosene (C11-C16) ~ rocketand jet fuel
fuel oil (C14-C18) ~ domesticheating
lubricating oil (C15-C24) ~lubricants for automobiles andmachines
Alkanes – saturated hydrocarbons(CnH2n+2)
methane ethane hexane
3-methylpenthane
! Alkanes are not planar !
A reservoir is that volume of rock that occurs down dip of a sealand up dip of the 100% Sw oil-free level. The HCs in the pore arein pressure and Sw equilibrium with the free water level
A petroleum reservoir is an accumulation of hydrocarbon(oil-gas-water) in porous rock
What is a Hydrocarbon reservoir..?
A reservoir is that volume of rock that occurs down dip of a sealand up dip of the 100% Sw oil-free level. The HCs in the pore arein pressure and Sw equilibrium with the free water level
DebrisMud-rich slope basinSubmarine canyonSubmarine fan channelSubmarine fan lobeGravel-rich slope
Not Deep – Water
Deep – Water
Petroleum Geology System
Basic elements of Petroleum Systems Describe plate tectonics and sedimentary basins Recognize names of major sedimentary rock types Describe importance of sedimentary environments to petroleum
industry Describe the origin of petroleum Identify hydrocarbon trap types Define and describe the important geologic controls on reservoir
properties, porosity and permeability
Objectives for the participantsat least…can understand the topics of :
Basic elements of Petroleum Systems Describe plate tectonics and sedimentary basins Recognize names of major sedimentary rock types Describe importance of sedimentary environments to petroleum
industry Describe the origin of petroleum Identify hydrocarbon trap types Define and describe the important geologic controls on reservoir
Scales of Investigation Used inReservoir Characterization
Gigascopic Well Test
Reservoir Model
Relative Volume
1014
300 m
50 m
300 m
Megascopic
Macroscopic
Microscopic
Reservoir ModelGrid Cell
Wireline LogInterval
Core Plug
GeologicalThin Section
1
2 x 1012
3 x 107
5 x 102
300 m
5 m 150 m
2 m1 m
cm
mm - m
(modified from Hurst, 1993)
Classification of Hydrocarbon Reservoir
Petroleum reservoirs are broadly classified asoil or gas reservoirs.
The composition of the reservoir hydrocarbonmixture
Initial reservoir pressure and temperature
Classification of Hydrocarbon Reservoir
Petroleum reservoirs are broadly classified asoil or gas reservoirs.
The composition of the reservoir hydrocarbonmixture
Initial reservoir pressure and temperature
Pressure Temperature Diagram
Figure 1-1• shows a typical pressure-temperature diagram of multi component
system with a specific overall composition. Although differenthydrocarbon system would have a different phase diagram, thegeneral configuration is similar.
These multi component pressure-temperature diagrams are essentiallyused to:
• Classify reservoirs• Classify the naturally occurring hydrocarbon systems• Describe the phase behavior of the reservoir fluid
Pressure Temperature Diagram
Figure 1-1• shows a typical pressure-temperature diagram of multi component
system with a specific overall composition. Although differenthydrocarbon system would have a different phase diagram, thegeneral configuration is similar.
These multi component pressure-temperature diagrams are essentiallyused to:
• Classify reservoirs• Classify the naturally occurring hydrocarbon systems• Describe the phase behavior of the reservoir fluid
Critical point• The critical point for a multi component mixture is referred to as the
state of pressure and temperature at which all intensive properties ofthe gas and liquid phases are equal (point C). At the critical point, thecorresponding pressure and temperature are called the criticalpressure pc and critical temperature Tc of the mixture.
Pressure Temperature Diagram (Continue...)
Bubble-point curve• The bubble-point curve (line BC) is defined as the line separating the
liquid phase region from the two-phase region.
Bubble-point curve• The bubble-point curve (line BC) is defined as the line separating the
liquid phase region from the two-phase region.
Dew-point curve• The dew-point curve (line AC) is defined as the line separating the
vapor-phaseregion from the two-phase region.
Oil Reservoirs• If the reservoir temperature
T is less than the criticaltemperature Tc of thereservoir fluid, the reservoiris classified as an oil reservoir.
Pressure Temperature Diagram (Continue...)
Gas reservoirs• If the reservoir temperature
is greater than the criticaltemperature of thehydrocarbon fluid, thereservoir is considered a gasreservoir.
Gas reservoirs• If the reservoir temperature
is greater than the criticaltemperature of thehydrocarbon fluid, thereservoir is considered a gasreservoir.
Oil Reservoirs• If the reservoir temperature
T is less than the criticaltemperature Tc of thereservoir fluid, the reservoiris classified as an oil reservoir.
Oil Reservoir Base on P-T Diagram
Low-shrinkage oil• Oil formation volume factor less
than 1.2 bbl/STB• Gas-oil ratio less than 200 scf/STB• Oil gravity less than 35° API• Black or deeply colored
• In general, if the reservoir temperature is above the criticaltemperature of the hydrocarbon system, the reservoir isclassified as a natural gas reservoir. On the basis of theirphase diagrams and the prevailing reservoir conditions, naturalgases can be classified into 3 categories:• Retrograde gas-condensate• Wet gas• Dry gas
Gas Reservoirs
• In general, if the reservoir temperature is above the criticaltemperature of the hydrocarbon system, the reservoir isclassified as a natural gas reservoir. On the basis of theirphase diagrams and the prevailing reservoir conditions, naturalgases can be classified into 3 categories:• Retrograde gas-condensate• Wet gas• Dry gas
• If the reservoir temperature T liesbetween the critical temperature Tcand cricondentherm Tct of thereservoir fluid, the reservoir isclassified as a retrograde gas-condensate reservoir.
• The gas-oil ratio for a condensatesystem increases with time due to theliquid dropout and the loss of heavycomponents in the liquid.
• Condensate gravity above 50° API• Stock-tank liquid is usually water-white
or slightly colored.
Retrograde gas-condensate reservoir
• If the reservoir temperature T liesbetween the critical temperature Tcand cricondentherm Tct of thereservoir fluid, the reservoir isclassified as a retrograde gas-condensate reservoir.
• The gas-oil ratio for a condensatesystem increases with time due to theliquid dropout and the loss of heavycomponents in the liquid.
• Condensate gravity above 50° API• Stock-tank liquid is usually water-white
or slightly colored.
• Temperature of wet-gas reservoiris above the cri-condentherm ofthe hydrocarbon mixture. Becausethe reservoir temperature exceedsthe cri-condentherm of thehydrocarbon system, the reservoirfluid will always remain in the vaporphase region as the reservoir isdepleted isothermally, along thevertical line A-B.
Wet Gas Reservoir
• Temperature of wet-gas reservoiris above the cri-condentherm ofthe hydrocarbon mixture. Becausethe reservoir temperature exceedsthe cri-condentherm of thehydrocarbon system, the reservoirfluid will always remain in the vaporphase region as the reservoir isdepleted isothermally, along thevertical line A-B.
Wet-gas reservoirs are characterized by thefollowing properties:• Gas oil ratios between 60,000 to 100,000 scf/STB• Stock-tank oil gravity above 60° API• Liquid is water-white in color• Separator conditions, i.e., separator pressure and
temperature, lie within the two-phase region
Wet Gas Reservoir (Continue…)
Wet-gas reservoirs are characterized by thefollowing properties:• Gas oil ratios between 60,000 to 100,000 scf/STB• Stock-tank oil gravity above 60° API• Liquid is water-white in color• Separator conditions, i.e., separator pressure and
temperature, lie within the two-phase region
The hydrocarbon mixture existsas a gas both in the reservoir andin the surface facilities.Usually a system having a gas-oilratio greater than 100,000scf/STB is considered to be a drygas.
Dry Gas Reservoir
The hydrocarbon mixture existsas a gas both in the reservoir andin the surface facilities.Usually a system having a gas-oilratio greater than 100,000scf/STB is considered to be a drygas.
Reservoir Driving Mechanism
• Many reservoirs are boundedon a portion or all of theirperipheries by water bearingrocks called aquifers. Theaquifers may be so largecompared to the reservoirthey adjoin as to appearinfinite for all practicalpurposes, and they may rangedown to those so small as tobe negligible in their effectson the reservoir performance.Reservoir havea water drive
The Water-Drive Mechanism
• Many reservoirs are boundedon a portion or all of theirperipheries by water bearingrocks called aquifers. Theaquifers may be so largecompared to the reservoirthey adjoin as to appearinfinite for all practicalpurposes, and they may rangedown to those so small as tobe negligible in their effectson the reservoir performance.Reservoir havea water drive
Characteristics Trend
Reservoir pressure Declines very slowly (remains veryhigh)
Gas oil ratio Little change during the life ofthe reservoir (remains low)
The Water-Drive Mechanism (Continue)
Little change during the life ofthe reservoir (remains low)
Water production Early excess water production
Well behavior Flow until water production getsexcessive.
Oil recovery 35 to 75 %
Rock and Liquid Expansion
• When an oil reservoir initially exists at a pressure higher thanits bubble-point pressure, the reservoir is called an undersaturated oil reservoir.
• At pressures above the bubble-point pressure, crude oil,connate water, and rock are the only materials present. Asthe reservoir pressure declines, the rock and fluids expanddue to their individual compressibility's.
• At pressures above the bubble-point pressure, crude oil,connate water, and rock are the only materials present. Asthe reservoir pressure declines, the rock and fluids expanddue to their individual compressibility's.
• The reservoir rock compressibility is the result of two factors:• Expansion of the individual rock grains• Formation compaction
Solution-gas Drive, Gas-Cap Drive, Gravity Drive
This driving form may also bereferred to by the followingvarious terms:
• Solution gas drive• Dissolved gas drive• Internal gas drive
The Depletion Drive Mechanism
In this type of reservoir, theprincipal source of energy is a resultof gas liberation from the crude oiland the subsequent expansion of thesolution gas as the reservoirpressure is reduced. As pressurefalls below the bubble-pointpressure, gas bubbles are liberatedwithin the microscopic pore spaces
Gas Cap Drive
Gas-cap-drive reservoirs can beidentified by the presence of a gascap with little or no water drive asshown in figure on the left. Due tothe ability of the gas cap to expand,these reservoirs arecharacterized by a slow decline inthe reservoir pressure. The naturalenergy available to produce thecrude oil comes from the followingtwo sources:• Expansion of the gas-cap gas• Expansion of the solution gas as it
is liberated
Gas-cap-drive reservoirs can beidentified by the presence of a gascap with little or no water drive asshown in figure on the left. Due tothe ability of the gas cap to expand,these reservoirs arecharacterized by a slow decline inthe reservoir pressure. The naturalenergy available to produce thecrude oil comes from the followingtwo sources:• Expansion of the gas-cap gas• Expansion of the solution gas as it
is liberated
The mechanism of gravity drainageoccurs in petroleum reservoirs as aresult of differences in densities ofthe reservoir fluids. The effects ofgravitational forces can be simplyillustrated by placing a quantity ofcrude oil and a quantity of water in ajar and agitating the contents. Afteragitation, the jar is placed at rest,and the more denser fluid (normallywater) will settle to the bottom ofthe jar, while the less dense fluid(normally oil) will rest on top of thedenser fluid. The fluids haveseparated as a result of thegravitational forces acting on them.
The Gravity-Drainage-Drive Mechanism
The mechanism of gravity drainageoccurs in petroleum reservoirs as aresult of differences in densities ofthe reservoir fluids. The effects ofgravitational forces can be simplyillustrated by placing a quantity ofcrude oil and a quantity of water in ajar and agitating the contents. Afteragitation, the jar is placed at rest,and the more denser fluid (normallywater) will settle to the bottom ofthe jar, while the less dense fluid(normally oil) will rest on top of thedenser fluid. The fluids haveseparated as a result of thegravitational forces acting on them.
Characteristics Trend
Reservoir pressure Variable rates of pressure decline,depending principally upon the amountof gas conservation.
Gas oil ratio Low gas-oil ratio
Water production Little or no water production.
Well behavior Hi Water Cut
Oil recovery Near to 80 %
• Two combinations of driving forces can bepresent in combination drive reservoirs. Theseare (1) depletion drive and a weak water driveand; (2) depletion drive with a small gas cap anda weak water drive. Then, of course, gravitysegregation can play an important role in any ofthe aforementioned drives.
The Combination-Drive Mechanism
The driving mechanism most commonlyencountered is one in which both waterand free gas are available in some degreeto displace the oil toward the producingwells. The most common type of driveencountered, therefore, is acombination-drive mechanism asillustrated in Figure below.
• Two combinations of driving forces can bepresent in combination drive reservoirs. Theseare (1) depletion drive and a weak water driveand; (2) depletion drive with a small gas cap anda weak water drive. Then, of course, gravitysegregation can play an important role in any ofthe aforementioned drives.
Figure 4 Combination drive reservoir
Reservoir Calculation in General
Transition Zone Transition Zone
Volumetric Mechanics(Equations)
GAS:Area (Ac) x Thickness (Ft) x Avg Porosity (%) x Avg Sgi (%) x Bgi(SCF/RCF) x 43,560 sqft/ac = OGIP (SCF)
OIL:Area (Ac) x Thickness (Ft) x Avg Porosity (%) x Avg Soi (%) / Boi(RB/STB) x 7758.4 Bbls/AcFt = OOIP (STB)
Volumetric Mechanics(Equations)
GAS:Area (Ac) x Thickness (Ft) x Avg Porosity (%) x Avg Sgi (%) x Bgi(SCF/RCF) x 43,560 sqft/ac = OGIP (SCF)
OIL:Area (Ac) x Thickness (Ft) x Avg Porosity (%) x Avg Soi (%) / Boi(RB/STB) x 7758.4 Bbls/AcFt = OOIP (STB)
Volumetric Mechanics(Gross Reservoir Volume)
AREA: Productive area (map view), in acresSubdivide overall area into components that are calculated individuallybased on similar average reservoir thickness
THICKNESS: From reservoir or fluid top to contact or saturation cutoff, in feet
SUMMED (AREA(S) X THICKNESS) =
GROSS RESERVOIR VOLUME in AcreFeet
Volumetric Mechanics(Gross Reservoir Volume)
AREA: Productive area (map view), in acresSubdivide overall area into components that are calculated individuallybased on similar average reservoir thickness
THICKNESS: From reservoir or fluid top to contact or saturation cutoff, in feet
SUMMED (AREA(S) X THICKNESS) =
GROSS RESERVOIR VOLUME in AcreFeet
Volumetric Mechanics(Pore Volume)
GROSS RESERVOIR VOLUME (AcFt) x Average Porosity (%) withinproductive reservoir =
GROSS STORAGE (PORE) VOLUME (AcreFeet)
Volumetric Mechanics(Pore Volume)
GROSS RESERVOIR VOLUME (AcFt) x Average Porosity (%) withinproductive reservoir =
GROSS STORAGE (PORE) VOLUME (AcreFeet)
Volumetric Mechanics(Gross Oil/Gas Volume)
GROSS STORAGE (PORE) VOLUME (AcreFeet) xAVERAGE OIL (Soi) or GAS (Sgi) SATURATION (%) =
GROSS OIL or GAS VOLUME (AcreFeet)
===========================
Conversion to standard units of RBbls or RCF
AcreFeet x 7,758 Bbls/AcreFoot = Oil in Reservoir Barrels
AcreFeet x 43,560 Cubic Feet/AcreFoot = Gas in Reservoir Cubic Feet
Volumetric Mechanics(Gross Oil/Gas Volume)
GROSS STORAGE (PORE) VOLUME (AcreFeet) xAVERAGE OIL (Soi) or GAS (Sgi) SATURATION (%) =
GROSS OIL or GAS VOLUME (AcreFeet)
===========================
Conversion to standard units of RBbls or RCF
AcreFeet x 7,758 Bbls/AcreFoot = Oil in Reservoir Barrels
AcreFeet x 43,560 Cubic Feet/AcreFoot = Gas in Reservoir Cubic Feet
Volumetric Mechanics (Oil)(Conversion to Stock Tank Barrels)
FORMATION VOLUME FACTOR (Bo):
Rules of Thumb
‘Dead’ Oil (no dissolved gas): Bo ~ 1.0 (RB/STB)‘Gassy’ (deepish) Oil: Bo ~ 1.4 (RB/STB)‘Typical’ (shallower) Oil: Bo ~ 1.2 (RB/STB)
Oil Volume (RB) / Bo (RB/STB) = OOIP (STB)
Volumetric Mechanics (Oil)(Conversion to Stock Tank Barrels)
FORMATION VOLUME FACTOR (Bo):
Rules of Thumb
‘Dead’ Oil (no dissolved gas): Bo ~ 1.0 (RB/STB)‘Gassy’ (deepish) Oil: Bo ~ 1.4 (RB/STB)‘Typical’ (shallower) Oil: Bo ~ 1.2 (RB/STB)
Oil Volume (RB) / Bo (RB/STB) = OOIP (STB)
Volumetric Mechanics (Gas)(Conversion to Standard Cubic Feet)
RECOVERY FACTOR (RF): As Function of• Reservoir Quality, Depth, Pressure, Temperature• Fluid Properties• Drive Mechanism(s)• Reservoir Management
Rules of Thumb
The better the reservoir, the better the recovery factor• Even fluid movement• Larger pore throats (better sweep, more moveable oil/gas)• Better water support (if any to be had)• Better effectiveness in secondary/ tertiary recovery projects
ReservesFrom OOIP / OGIP
(What can you take to the bank ?)
RECOVERY FACTOR (RF): As Function of• Reservoir Quality, Depth, Pressure, Temperature• Fluid Properties• Drive Mechanism(s)• Reservoir Management
Rules of Thumb
The better the reservoir, the better the recovery factor• Even fluid movement• Larger pore throats (better sweep, more moveable oil/gas)• Better water support (if any to be had)• Better effectiveness in secondary/ tertiary recovery projects
Probabilistic Volumetrics(Because there is no single answer)
• Calculate a range of values based on confidence in variables.P = Probability Factor
P 100 – dead certaintyP 70 to 90 – high confidenceP 10 to 30 – low confidence
• For each variable with significant uncertaintyAssign P 90 , P 50, and P 10 values to create distributionExample: Productive area – P 90 = smallest reasonable area, P 50 = mostlikely area, and P 10 = maximum area (but not unreasonable)
• Qualitative (‘fudgability’ - what do you want it to be ?)Usefulness a function of experience in areaRequires objective assessmentMost beneficial when comparing large projects in which data is sparse
Probabilistic Volumetrics(Because there is no single answer)
• Calculate a range of values based on confidence in variables.P = Probability Factor
P 100 – dead certaintyP 70 to 90 – high confidenceP 10 to 30 – low confidence
• For each variable with significant uncertaintyAssign P 90 , P 50, and P 10 values to create distributionExample: Productive area – P 90 = smallest reasonable area, P 50 = mostlikely area, and P 10 = maximum area (but not unreasonable)
• Qualitative (‘fudgability’ - what do you want it to be ?)Usefulness a function of experience in areaRequires objective assessmentMost beneficial when comparing large projects in which data is sparse
Source (Material and Rocks)
Generation (Maturation)
Migration
Trap
Reservoir
Petroleum System Summary
Source (Material and Rocks)
Generation (Maturation)
Migration
Trap
Reservoir
ANY QUESTIONS..??
Confuse..? Or Sleepy…..???
End Of Presentation
THANKS FOR YOURATTENTION
TERIMA KASIHHATUR SUWUNMATUR SUWUN
WASSALAMU’ALIKUMAdios – C U Soon….In next Module
THANKS FOR YOURATTENTION
TERIMA KASIHHATUR SUWUNMATUR SUWUN
WASSALAMU’ALIKUMAdios – C U Soon….In next Module
THANKS FOR YOURATTENTION
TERIMA KASIHHATUR SUWUNMATUR SUWUN
WASSALAMU’ALIKUMAdios – C U Soon….In next Module
THANKS FOR YOURATTENTION
TERIMA KASIHHATUR SUWUNMATUR SUWUN
WASSALAMU’ALIKUMAdios – C U Soon….In next Module
References
Definitions / Conversions (I)
14.7 psi = Atmospheric (@ S.L.)5,280 feet per mile43,560 sq ft per acre640 acres per sq mile – Section (160 ac per quarter section) 247 ac/sqkm3.281 ft per meter (39.37 inches per meter)1.609 kilometers per mile2.54 centimeters per inch35.32 cubic feet per cubic meter7,758 STBarrels per acre-footSpecific Gravity (crude); .80-.97Btu value for gas: avg ~1Btu / cubic foot (1000Btu/MCF), rich - higher, a lot ofnon-hydrocarbons - lowerAPI gravity: 25=specific gravity .904, 42=specific gravity .816BOE: 6,000 cubic feet per barrel (average)
Definitions / Conversions (I)
14.7 psi = Atmospheric (@ S.L.)5,280 feet per mile43,560 sq ft per acre640 acres per sq mile – Section (160 ac per quarter section) 247 ac/sqkm3.281 ft per meter (39.37 inches per meter)1.609 kilometers per mile2.54 centimeters per inch35.32 cubic feet per cubic meter7,758 STBarrels per acre-footSpecific Gravity (crude); .80-.97Btu value for gas: avg ~1Btu / cubic foot (1000Btu/MCF), rich - higher, a lot ofnon-hydrocarbons - lowerAPI gravity: 25=specific gravity .904, 42=specific gravity .816BOE: 6,000 cubic feet per barrel (average)