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Reservoirs

Today‘s Lecture

• What is a reservoir ?• What types of reservoirs exist ?• Why study petroleum reservoirs ?• Three examples

• Links and Literature

Today‘s Lecture: Reservoirs What is a Petroleum Reservoir ?

A reservoir is that volume of rock that occurs downdip of a seal and updip of the 100% Sw oil-free level. The HCs in the pores are in pressure- and Sw-equilibrium with the free-water level.

A petroleum reservoir is an accumulation of oil (and gas) in porous rock.

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What kind of reservoirs ?

•Siliciclastic•Carbonate•Fractured

carbonate reservoir facies

• Marine embayment• Sabkha/tidal flat• Restricted shelf/lagoon• Open shelf• Nearshore bar/beach• Offshore bar• Platform/ramp margin shoal• High-energy ramp• Pinnacle reef• Patch reef• Reef mound• Barrier reef• Fringing reef• Skeletal bank• Mud-rich reef mound• Mud-rich skeletal bank• Karst-related detrital wedge• Debris flow/turbidite• Pelagic• Coquina bank

C&C reservoirs

Siliciclastic reservoir facies

Not deep-water• Alluvial fan

• Meandering river• Braided river• Straight/anastomosing river

• Mixed aeolian/fluvial• Erg• Lacustrine delta• Shoreline/shelf• Estuary• Coastal plain• Tidal flat• Barrier-island/lagoon• Strandplain/chenier• Shoreface-shelf

• Delta• Glaciofluvial• Lacustrine river-delta• Lacustrine fan-delta• Fluvial-dominated delta• Wave-dominated delta• Tide-dominated delta• Mixed-influence delta• Marine fan-delta

Deep-water• Debris flow/turbidite• Pelagic• Sublacustrine fan

• Gravel-rich slope/basin• Mud-rich slope/basin• Submarine canyon• Slope apron

• Submarine-fan channel• Submarine-fan lobe• Submarine-fan lobe• Submarine-fan channel levee

C&C reservoirs

Fractured reservoirs

• BASEMENT• BURIAL DOLOMITE• CARBONATE SAND• CHERT AND SILICEOUS SHALE• COAL BED• FORESLOPE CARBONATE• FORESLOPE CHALK• FORESLOPE CHERT• MICROPOROUS CHERT• MICROPOROUS DIATOMITE• MICROPOROUS DOLOMITE• MICROPOROUS LIMESTONE• MUDDY CARBONATE• MUDDY DOLOMITE• ORGANIC BUILDUP• SHALE• SHALE AND SILTSTONE• SHELF CHALK• SILICEOUS SHALE• TIGHT SANDSTONE• VOLCANICS• KARSTIC/ CARBONATE SAND• KARSTIC/ MUDDY CARBONATE• KARSTIC/ MUDDY DOLOMITE• KARSTIC/ ORGANIC BUILDUP• LOW-RESISTIVITY SANDSTONE• TIGHT CONGLOMERATE• TIGHT SANDSTONE

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Zhanjiajie, Hunan Province

A reservoir is a tank to be drained

The view of your Petroleum Engineer

Questions you need to answer

• What is the most efficient way to empty the tank ?• What do I need to know about its internal structure ?• What obstacles am I likely to encounter ?

One of the main objectives of reservoir geology evaluation is toexamine the impact of reservoir heterogeneities on reservoir behaviour.

Why study Petroleum Reservoirs ?

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1-100µ

0.1-10 mm

1-10 cm

0.1-1m

0.1-10 km

Levels of Reservoir Heterogeneity

1- 100 m

k, So/Sw , flow, formation damage

Flow patterns, drainage efficiency,

vertical and lateral sweep efficiency

HC volume, areal distribution,

play trends

How is permeability (k) and porosity (φ) related ?

Grain and Pore Scale

Kaolinite

Hairy IlliteRotliegendes-Problem

http://www.creationresearch.org/vacrc/sem02.html

“The geological and reservoir properties of sedimentary rocks depend upon an interplay of tectonics, sea level, sediment supply, physical and biological processes of sediment transport and deposition, and climate.”

Reservoir Heterogeneity Matrix

Back barrierFluvially-dom. deltaFine-grained meanderbeltSubmarine fans

Coarse-grained meander beltBraid delta

Basin-floor turbidites

High

Braided streamTide-domainated delta

Shelf barsAlluvial fansFan deltaLacustrine deltaDistal delta frontWave-modified delta(proximal)

EolianWave-modified delta(distal)

Meander beltFluvially-dominateddeltaBack barrier

Delta-front mouth barProximal delta frontTidal depositsMud-rich strand plain

Wave-dominated deltaBarrier coreBarrier shorefaceSand-rich shoreface

Low

HighModerateLow

Lateral Heterogeneity

Vertical

Hetero

gen

eity

Moderate

5

0,1

1

10

100

1000

10000

0 5 10 15 20 25 30 35

Depositional Environments

Porosity (%)

Air P

erm

eabi

lity

(mD

)

Swamp

Lagoon

Tidal Flat

Tidal Ridge

Barrier Bar Beach

Average and Limits of porosity and permeability

After Nagtegaal, 1978; modified from Selley, 1998

DEs take influence through grain size, sorting, clay content, mineralogy

How is permeability (k) and porosity (φ) related ?

Reservoir-Scale: 3-Dimensionality; Heterogeneity

φ max ?φ min

Kmax ?K min ?

Namib

http://www.bdrg.esci.keele.ac.uk/Staff/mountney/sedimentary_research/sed_research_frames.htm

Navajo Sandstone, UtahÄolische Dünen

Instructions from a Guru(Bob Sneider) What data are available ?

Pressure (sand body connectedness)Repeat Formation Tester

Pcurrent directions, lithofaciesLithology, curve shape analysisPorosity, curve shape analysis

LogsFMS / FMISP,GRSonic, density, neutron

Water depth, dep environment, time line; pcurrent direction, lithofacies

Paleontology (micro, macro, traces), Palynology

Facies, dep environmentPaleocourrent directionsMineralogy, lithologyMineralogy, lithology

Core (slabbed or oriented)Sidewall coresCuttingsThin sections

UseData Type

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How is permeability (k) and porosity (φ) related ?

Basin scale

CoreLab PromotionaryMaterial

Three samples of ~21 % porosity

CoreLab PromotionaryMaterial

Three samples of ~21 % porosity

CoreLab PromotionaryMaterial

Three samples of ~21 % porosity

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How does depositionalenvironment affect reservoir

properties ?

Deep-water fan morphology

Upper Fan

Mid-Fan

Lower Fan

Channel-Mouth Bar

Lobe Fringe

Basin Plain

Lobes

Slope

Lobes

Lobes

Lobes

OverbanksChannels

Basin PlainG

SlopeF

OverbankE

Lobe FringeD

LobeC

Distal ChannelB

ProximalChannelA

Reservoir PotentialLow high

DepositionalPorosity

low high

Lateral ContinuityPoor good

LayerThickness1 10 100

Lithologyms ss cgl

PrincipalEnvironment

MuttiFacies

Reservoir potential of turbidite facies Example: Model of deep-water fan morphology

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Three Examples

• Prudhoe Bay Field, Alaska• Seneca Field, Ohio• Pecos Field, Alberta

All scanned graphs from articles in

John H. Barwis, John G. McPherson, Joseph R.J. Studlick, 1990, SandstonePetroleum Reservoirs (Casebooks in Earth Sciences): Springer Verlag New York, 582 p.

•Prudhoe Bay Field, Alaska

Prudhoe Bay Field, Alaska

http://www.arcticphoto.co.uk

http://www.channel6.dk/native/uk/page214.html

Prudhoe Bay Field, Alaska

Permian braid-plain stream and gravelly delta deposits

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Prudhoe Bay Field, Alaska / Salar del Carmen, N ChilePrudhoe Bay Field, Alaska / Sierra de Argomedo, N Chile

Prudhoe Bay Field, Alaska / Sierra de Argfomedo, N Chile Prudhoe Bay Field, Alaska

Vertical view from bridge, south of Santa Cruz

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Type log• Lithology• Permeability• Porosity• Depositional

Environment

Relationship between petrophysical and geological parameter

Which facies has the better reservoir quality ?

Seneca Gas Field

Lower Silurian isopach map (in ft) in SE Ohio showing 3 major depositional lobes

Seneca Gas Field: Log-correlation

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Seneca Gas Field: Core sketchesSeneca Gas Field: Sand Isopachs

Seneca Gas Field: Sand Isopachs Seneca Gas Field: Sand Isopachs

Prallhang

GleithangMäander

Altwasser (abgeschnittenerMäanderarm)

Mäanderhals (zukünftigeAbkürzung des Flußlaufs)

Flussaue

Gleithang

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Seneca Gas Field: Sand Isopachs Seneca Gas Field: Detailed isopach mapping

“Birdfoot Delta” geometry

Peco Gas Field: Structural Cross section

Anticline in footwall of thrust sheet

Peco Gas Field: Structure Map Top Reservoir

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Peco Gas Field: Type log description

Fining-upward fluvial facies

Peco Gas Field: Stratigraphic cross-section Through Peco A, N Pool

Thickness and lateral extent of reservoir

Peco Gas Field: Facies, reservoir character

Lectura 11 (Summary: Reservesand Resources, unconventional HC)

Lab 10 (PetroMod)

Lectura 10 (Exploration: Hydrocarbon classificationof basins; play types)

Vi

Lectura 8 (Geophysics in exploration and reservoirmanagement)

Lab 9 (Loggingexercise)

Lectura 9 (Loggingconcepts and tools; quantitative evaluation of lithology, fluids, and porosity)

Ju

Lectura 7 (Reservoir engineering: Drive mechanisms, phase behavior, production problems, scaleformation etc.)

Lab 5 (Boundwater, capillarityexercise)

Lectura 5 (Reservoir petrophysics: capillarypressure, pore-sizedistribution, bound wateretc.)

Mi

Lectura 6 (The reservoir: Lithology, geometry, and facies. Reservoir characterization and management)

Lab 4 (Porositycalculation)

Lectura 4 (porosidad, permeabilidad)

Ma

Lectura 3 (Geochemistry: Origin of HC; organic matter, source rocks, accumulation. The "petroleumkitchen")

Lab 2 (Internet resources)

Lectura 1 / 2 (Introduction; The petroleum system)

Lu

15:15-16:4511:30-13:009:15-10:45

LecturaPracticaLectura

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Links•http://www.ccreservoirs.com/reservoirtypes.htm

(3 lists of approx. 300 fields in each category; along with some short description / classification: good enough for a start).

Literature• John H. Barwis, John G. McPherson, Joseph R.J.

Studlick, 1990, Sandstone Petroleum Reservoirs (Casebooks in Earth Sciences): Springer Verlag New York, 582 p.

Links and Literature