1. Today‘s Lecture
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Prof. Christoph Heubeck
Institut für Geologische Wissenschaften
Freie Universität Berlin
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Today‘s Lecture: Reservoirs What is a Petroleum Reservoir ?
• What is a reservoir ? A petroleum reservoir is an accumulation
• What types of reservoirs exist ? of oil (and gas) in porous rock.
• Why study petroleum reservoirs ?
• Three examples
• Links and Literature
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.
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2. What kind of reservoirs ? 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
•
• Siliciclastic •
•
Patch reef
Reef mound
Barrier reef
• Carbonate •
•
Fringing reef
Skeletal bank
• Fractured •
•
Mud-rich reef mound
Mud-rich skeletal bank
• Karst-related detrital wedge
• Debris flow/turbidite
• Pelagic
• Coquina bank
C&C reservoirs
Siliciclastic reservoir facies Fractured reservoirs
Not deep-water Deep-water • BASEMENT
• Alluvial fan • Debris flow/turbidite • BURIAL DOLOMITE
• Pelagic • CARBONATE SAND
• Meandering river • Sublacustrine fan • CHERT AND SILICEOUS SHALE
• Braided river • COAL BED
• Straight/anastomosing river • Gravel-rich slope/basin • FORESLOPE CARBONATE
• Mud-rich slope/basin • FORESLOPE CHALK
• Mixed aeolian/fluvial • Submarine canyon • FORESLOPE CHERT
• Erg • Slope apron • MICROPOROUS CHERT
• Lacustrine delta • MICROPOROUS DIATOMITE
• Shoreline/shelf • Submarine-fan channel • MICROPOROUS DOLOMITE
• Estuary • Submarine-fan lobe • MICROPOROUS LIMESTONE
• Coastal plain • Submarine-fan lobe • MUDDY CARBONATE
• Tidal flat • Submarine-fan channel levee • MUDDY DOLOMITE
• Barrier-island/lagoon • ORGANIC BUILDUP
• Strandplain/chenier • SHALE
• Shoreface-shelf • SHALE AND SILTSTONE
• SHELF CHALK
• Delta • SILICEOUS SHALE
• Glaciofluvial • TIGHT SANDSTONE
• Lacustrine river-delta • VOLCANICS
• Lacustrine fan-delta • KARSTIC/ CARBONATE SAND
• Fluvial-dominated delta • KARSTIC/ MUDDY CARBONATE
• Wave-dominated delta • KARSTIC/ MUDDY DOLOMITE
• Tide-dominated delta • KARSTIC/ ORGANIC BUILDUP
• Mixed-influence delta • LOW-RESISTIVITY SANDSTONE
• Marine fan-delta • TIGHT CONGLOMERATE
C&C reservoirs • TIGHT SANDSTONE
2

3. Zhanjiajie, Hunan Province
The view of your Petroleum Engineer
A reservoir is a tank to be drained
Why study Petroleum Reservoirs ?
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 to
examine the impact of reservoir heterogeneities on reservoir
behaviour.
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4. Levels of Reservoir Heterogeneity How is permeability (k) and porosity (φ) related ?
Flow patterns, Grain and Pore Scale
drainage efficiency,
vertical and lateral sweep efficiency
0.1-
1m
k, So/Sw , flow,
formation damage 1-10
cm
1- 100
m
0.1-10
mm
http://www.creationresearch.org/vacrc/sem02.html
Hairy Illite
0.1-10 Rotliegendes-
km
1-100µ
Problem
HC volume, Kaolinite
areal distribution,
play trends
Reservoir Heterogeneity Matrix
Low Moderate High
Wave-dominated delta Delta-front mouth bar Meander belt
Barrier core Proximal delta front Fluvially-dominated
Low delta
Barrier shoreface Tidal deposits
Sand-rich shoreface Mud-rich strand plain Back barrier
“The geological and reservoir properties of sedimentary rocks depend
Vertical Heterogeneity
upon an interplay of tectonics, sea level, sediment supply, physical and Eolian Shelf bars Braided stream
biological processes of sediment transport and deposition, and climate.” Wave-modified delta Alluvial fans Tide-domainated delta
Moderate
(distal) Fan delta
Lacustrine delta
Distal delta front
Wave-modified delta
(proximal)
Basin-floor turbidites Coarse-grained meander belt Back barrier
Braid delta Fluvially-dom. delta
High Fine-grained meander
belt
Submarine fans
Lateral Heterogeneity
4

5. Depositional Environments How is permeability (k) and porosity (φ) related ?
10000
DEs take influence Reservoir-Scale: 3-Dimensionality; Heterogeneity
Beach through grain size,
Barrier Bar
sorting, clay content,
1000 mineralogy
Tidal Flat
Tidal Ridge
Air Permeability (mD)
100
10
Navajo Sandstone, Utah
Äolische Dünen
Lagoon
Average and
Limits of
1
porosity and Kmax ? φ max ?
Swamp permeability K min ? φ min
0,1
0 5 10 15 20 25 30 35
Namib
After Nagtegaal, 1978; Porosity (%)
modified from Selley, 1998 http://www.bdrg.esci.keele.ac.uk/Staff/mountney/sedimentary_research/sed_research_frames.htm
Instructions from a Guru
(Bob Sneider) What data are available ?
Data Type Use
Core (slabbed or oriented) Facies, dep environment
Sidewall cores Paleocourrent directions
Cuttings Mineralogy, lithology
Thin sections Mineralogy, lithology
Paleontology (micro, macro, traces), Water depth, dep environment, time
Palynology line; pcurrent direction, lithofacies
Logs
FMS / FMI Pcurrent directions, lithofacies
SP,GR Lithology, curve shape analysis
Sonic, density, neutron Porosity, curve shape analysis
Repeat Formation Tester Pressure (sand body connectedness)
5

6. How is permeability (k) and porosity (φ) related ?
Basin scale Three samples of
~21 % porosity
CoreLab Promotionary
Material
Three samples of Three samples of
~21 % porosity ~21 % porosity
CoreLab Promotionary CoreLab Promotionary
Material Material
6

7. Deep-water fan morphology
Slope
Upper Fan Channels
Overbanks
Lobes
How does depositional Channel-
Mouth Bar
environment affect reservoir Mid-Fan
Lobes
properties ? Lobes
Lobe
Lobes Fringe
Basin Plain
Lower Fan
Example: Model of deep-water fan morphology
Reservoir potential of turbidite facies
Mutti Layer Lateral Depositional Reservoir
Principal Lithology
Thickness Continuity Porosity Potential
Facies Environment ms ss cgl
1 10 100 Poor good low high Low high
Proximal
A
Channel
B Distal Channel
C Lobe
D Lobe Fringe
E Overbank
F Slope
G Basin Plain
7

8. Three Examples •Prudhoe Bay Field, Alaska
• 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, Sandstone
Petroleum Reservoirs (Casebooks in Earth Sciences): Springer Verlag New York,
582 p.
Prudhoe Bay Field, Alaska Prudhoe Bay Field, Alaska
http://www.arcticphoto.co.uk
Permian braid-plain stream
http://www.channel6.dk/native/uk/page214.html
and gravelly delta deposits
8

9. Prudhoe Bay Field, Alaska / Salar del Carmen, N Chile
Prudhoe 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
9

10. Type log Relationship between petrophysical and geological parameter
• Lithology
• Permeability
• Porosity
• Depositional
Environment
Which facies has the better reservoir quality ?
Seneca Gas Field Seneca Gas Field: Log-correlation
Lower Silurian isopach map (in
ft) in SE Ohio showing 3 major
depositional lobes
10

11. Seneca Gas Field: Sand Isopachs
Seneca Gas Field: Core sketches
Seneca Gas Field: Sand Isopachs Seneca Gas Field: Sand Isopachs
Altwasser (abgeschnittener
Mäanderarm)
Mäander Gleithang
Prallhang
Flussaue
Gleithang
Mäanderhals (zukünftige
Abkürzung des Flußlaufs)
11

12. Seneca Gas Field: Sand Isopachs Seneca Gas Field: Detailed isopach mapping
“Birdfoot Delta” geometry
Peco Gas Field: Structural Cross section Peco Gas Field: Structure Map Top Reservoir
Anticline in footwall of thrust sheet
12

13. Peco Gas Field: Type log description Peco Gas Field: Stratigraphic cross-section Through Peco A, N Pool
Fining-upward fluvial
facies
Thickness and lateral
extent of reservoir
Peco Gas Field: Facies, reservoir character
Lectura Practica Lectura
9:15-10:45 11:30-13:00 15:15-16:45
Lu Lectura 1 / 2 (Introduction; Lab 2 (Internet Lectura 3 (Geochemistry: Origin of
The petroleum system) resources) HC; organic matter, source rocks,
accumulation. The "petroleum
kitchen")
Ma Lectura 4 (porosidad, Lab 4 (Porosity Lectura 6 (The reservoir: Lithology,
permeabilidad) calculation) geometry, and facies. Reservoir
characterization and management)
Mi Lectura 5 (Reservoir Lab 5 (Bound Lectura 7 (Reservoir engineering:
petrophysics: capillary water, capillarity Drive mechanisms, phase behavior,
pressure, pore-size exercise) production problems, scale
distribution, bound water formation etc.)
etc.)
Ju Lectura 9 (Logging Lab 9 (Logging Lectura 8 (Geophysics in
concepts and tools; exercise) exploration and reservoir
quantitative evaluation of management)
lithology, fluids, and
porosity)
Vi Lectura 10 (Exploration: Lab 10 (Petro Lectura 11 (Summary: Reserves
Hydrocarbon classification Mod) and Resources, unconventional HC)
of basins; play types)
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14. Links and Literature
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.
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