Geologic Storage

7/30/2019 Geologic Storage

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Geologic Storage Formation

Classiications: Understanding Its

Importance and Impacts on CCS

Opportunities in the United States

September 2010


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Disclaimer

This report was prepared as an account o work sponsored by an agency o the United States

Government. Neither the United States Government nor any agency thereo, nor any o their

employees, makes any warranty, express or implied, or assumes any legal liability or responsibility

or the accuracy, completeness, or useulness o any inormation, apparatus, product, or process

disclosed, or represents that its use would not inringe privately owned rights. Reerence therein

to any speciic commercial product, process, or service by trade name, trademark, manuacturer, or

otherwise does not necessarily constitute or imply its endorsement, recommendation, or avoring by

the United States Government or any agency thereo. The views and opinions o authors expressed

therein do not necessarily state or relect those o the United States Government or any agency

thereo.

Cover PhotosCredits for images shown on the cover arenoted with the corresponding figures within this document.


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Geologic Storage Formation Classiications:

Understanding Its Importance and Impacts on CCS

Opportunities in the United States

September 2010

National Energy Technology Laboratory

www.netl.doe.gov

DOE/NETL-2010/1420


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Table of Contents

Executive Summary ____________________________________________________________________________ 10

1.0 Introduction and Background Geology_________________________________________________________ 11

1.1 Geologic Background_______________________________________________________________________________ 131.2 Igneous Rocks _____________________________________________________________________________________ 14

1.3 Metamorphic Rocks ________________________________________________________________________________ 16

1.4 Sedimentary Rocks_________________________________________________________________________________ 16

2.0 Characteristics of Storage Reservoirs and Confining Units_________________________________________ 20

2.1 Reservoir Properties _______________________________________________________________________________20

2.2 Sealing and Trapping Mechanisms ___________________________________________________________________21

3.0 Depositional Environments __________________________________________________________________ 24

3.1 Deltaic Reservoir Properties_________________________________________________________________________28

Deltaic Depositional Environment _______________________________________________________________________28

3.2 Carbonate Reservoir and Ree Reservoir Properties ____________________________________________________32

Carbonate Depositional Systems ________________________________________________________________________32

Reef Depositional System ______________________________________________________________________________33

3.3 Turbidites Reservoir Properties ______________________________________________________________________34

Turbidite Depositional System___________________________________________________________________________34

3.4 Strandplain Reservoir Properties ____________________________________________________________________36

Strandplain Depositional System ________________________________________________________________________36

Barrier Island Depositional System _______________________________________________________________________373.5 Alluvial and Fluvial Fan Reservoir Properties __________________________________________________________38

Alluvial Depositional Systems ___________________________________________________________________________38

Fluvial Depositional Systems____________________________________________________________________________38

3.6 Eolian Reservoir Properties _________________________________________________________________________40

Eolian Depositional Systems ____________________________________________________________________________40

3.7 Lacustrine Reservoir Properties______________________________________________________________________41

Lacustrine Depositional Systems_________________________________________________________________________41

Evaporites Depositional System _________________________________________________________________________42

3.8 Basalt Reservoir Properties _________________________________________________________________________42

4.0 The Road to Commercialization_______________________________________________________________ 44

References ____________________________________________________________________________________ 48

Section 1 References __________________________________________________________________________________48

Sections 2 and 3 References ___________________________________________________________________________48

Section 4 References __________________________________________________________________________________53

Table of Contents


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List of Figures

Figure 1-1. Schematic o CO2

rom a Thermoelectric Power Plant and Reinery being

stored in Various Geologic Formations. ___________________________________________________ 12

Figure 1-2. Formation and Distribution o Igneous Rock in the Earths Crust. _______________________________ 14

Figure 1-3. Cut and polished granite showing pink and white quartz crystals and black mica. _________________ 15

Figure 1-4. Basalt. ______________________________________________________________________________ 15

Figure 1-5. Distribution o Known Basalt Formations in the United States and Canada

Investigated by NETL. _________________________________________________________________ 15

Figure 1-6. Slate, a ine-grained, oliated, metamorphic rock that was ormerly shale. _______________________ 16

Figure 1-7. Schist a metamorphic rock where heat and pressure have elongated individual minerals. __________ 16

Figure 1-8. Environments or Weathering and Deposition o Rocks that can ProduceSedimentary Clastic Deposits.___________________________________________________________ 17

Figure 1-9. Environments or Formation o Carbonate Rocks. ___________________________________________ 17

Figure 1-10. Cut sandstone core rom Eolian deposit showing banding, ___________________________________ 17

Figure 1-11. Close-up o coral pink sandstone rom Eolian ormation, _____________________________________ 17

Figure 1-12. Course sandstone showing bedding planes. _______________________________________________ 18

Figure 1-13. Shale with parallel bands or layers. _______________________________________________________ 18

Figure 1-14. Etched limestone showing shells and calcareous debris rom Kope Formation, Ohio. ______________ 18

Figure 1-15. Map o Oil and Gas Fields Superimposed on Saline Basins o North America. _____________________ 19

Figure 1-16. Distribution o Known Coal Basins Investigated by NETL. _____________________________________ 19

Figure 2-1. Porosity in Rocks and Rock Permeability. __________________________________________________ 20

Figure 2-2. Microscopic Schematic o Rock Porosity and Permeability. ____________________________________ 21

Figure 2-3. Shale, sand, and anhydrite core rom Colorado and well-sorted beach sand. _____________________ 22

Figure 2-4. Capillary trapping o CO2. ______________________________________________________________ 23

Figure 2-5. Structural traps: (let) Anticline, (center) Fault, (right) Salt Dome as trap. _________________________ 23

Figure 3-1. Components o a Deltaic System. ________________________________________________________ 28

Figure 3-2. Mississippi River Delta, United States, Lobe Development over the Last 5,000 years. _______________ 28

Figure 3-3. Mississippi River Delta, United States. A Recently Developed Elongated Shaped

Delta that is River-Dominated. __________________________________________________________ 28

Figure 3-4. Nile River Delta, Egypt. A Lobe Shaped Delta that is Wave-Dominated. __________________________ 29

List of Figures


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Figure 3-5. Rhone River, France. A Wave-Dominated Elongated Delta.. ___________________________________ 29

Figure 3-6. Ganges/Brahmaputra River Delta, Bangladesh. _____________________________________________ 29

Figure 3-7. As Time, Heat and Pressure Increase during Coaliication, the Lignite Changes into

Bituminous and Finally Anthracite Coal. ___________________________________________________ 30

Figure 3-8. Structure o coal and the cleat system within. ______________________________________________ 31

Figure 3-9. Carbonate Depositional System. An idealized block diagram o carbonate depositional

environments based on Pennsylvanian carbonates in southeastern Utah. _______________________ 32

Figure 3-10. Groundwater zones. __________________________________________________________________ 33

Figure 3-11. Pinnacle Ree Development in Alberta. ___________________________________________________ 34

Figure 3-12. A. Coarse-grained, Sand-rich Turbidite System and B. Fine-grained, Mud-rich

Turbidite System. _____________________________________________________________________ 35

Figure 3-13. Strandplain Deposit along the South Carolina Coast. ________________________________________ 36

Figure 3-14. Strandplain near the mouth o the Kugaryuak River, Coronation Gul, Southwest

Kitikmeot Region, Nunavut, Canada. _____________________________________________________ 36

Figure 3-15. Barrier Island with Beach and Back Dune Areas. ____________________________________________ 37

Figure 3-16. Barrier Island along the Texas Coast. _____________________________________________________ 37

Figure 3-17. Badwater Fan, Death Valley, Caliornia. ___________________________________________________ 38

Figure 3-18. Large alluvial an between the Kunlun and Altun mountains, XinJiang Province, China. ____________ 38

Figure 3-19. Google Earth Image o Bhramapura River System, Bangladesh showing Braided

stream system depositing sediment rom the Himalayan Mountains. ___________________________ 39

Figure 3-20. Closer Image o Braided River Fluvial Depositional System. ___________________________________ 39

Figure 3-21. Braided River Flowing on a previously Glaciated Flat near Peyto Lake, Ban

National Park, Canadian Rockies, Alberta, Canada. __________________________________________ 39

Figure 3-22. Block diagram o a meandering stream (A) and braided stream (B) showing lateral

migration o channel and point bar sequence and environmental relationships. __________________ 40

Figure 3-23. The Namib Desert Dune Ridge System. ___________________________________________________ 41

Figure 3-24. A Lacustrine Formation Being Deposited in a Hydrologically Closed System. _____________________ 41

Figure 3-25. Evaporite Deposits being ormed on the Caribbean Island o Bonaire. __________________________ 42

Figure 3-26. Major Internal Features o a Columbia River Basalt Group (North America) Lava Flow. ______________ 43

Figure 4-1. Matrix o NETL CO2

Geosequestration Projects and Depositional Environments. __________________ 47

List of Figures


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List of Tables

Table 3-1. Reservoir Depositional Classiication Schematic. ___________________________________________ 25

Table 3-2. Characteristics o Depositional Reservoirs. ________________________________________________ 26

Table 4-1. CO2

Geosequestration Projects with Lithology and Geologic Classiication. _____________________ 44

List of Tables


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List of Acronyms and Abbreviations

Acronym/Abbreviation Defnition

ARRA ________________________ American Recovery and Reinvestment Act o 2009

Big Sky_______________________ Big Sky Carbon Sequestration Partnership

Btu__________________________ British thermal unit

CBM _________________________ Coalbed Methane

CCS _________________________ Carbon Capture and Storage

CH4

_________________________ Methane

CO2__________________________ Carbon Dioxide

CaCO3

_______________________ Calcium Carbonate

DOE _________________________ U.S. Department o Energy

ECBM ________________________ Enhanced Coalbed Methane

EOR _________________________ Enhanced Oil Recovery

EPA _________________________ U.S. Environmental Protection Agency

GHG _________________________ Greenhouse Gas

GIS __________________________ Geographic Inormation Systems

HFC _________________________ Hydrofuorocarbon

LIP __________________________ Large Igneous Provinces

MGSC________________________ Midwest Geological Sequestration Consortium

MORB _______________________ Mid-Ocean Ridge Basalts

MRCSP _______________________ Midwest Regional Carbon Sequestration Partnership

MWh ________________________ Megawatt Hour(s)N

2O _________________________ Nitrous Oxide

NRDC ________________________ Natural Resources Deense Council

NETL ________________________ National Energy Technology Laboratory

OIB __________________________ Ocean Island Basalts

OOIP ________________________ Original Oil in Place

PCOR ________________________ Plains CO2

Reduction Partnership

ppm _________________________ parts per million

RCSP ________________________ Regional Carbon Sequestration Partnership(s)

RD&D ________________________ Research, Design, and DemonstrationSECARB ______________________ Southeast Regional Carbon Sequestration Partnership

SWP _________________________ Southwest Regional Partnership on Carbon Sequestration

TDS _________________________ Total Dissolved Solids

USGS ________________________ U.S. Geological Survey

WAG ________________________ Water Alternating Gas

WESTCARB ___________________ West Coast Regional Carbon Sequestration Partnership

List of Acronyms and Abbreviations


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Matrix of Field Activities in Different Reservoir Classes

High Potential Reservoirs Medium Potential Reservoirs

Lower orUnknownPotential

Reservoirs

Large Scale FieldTests

1 1 3 1

Small Scale Field Tests 3 2 4 1 2 2 5 1

Site Characterization 1 8 6 3 3 2 2 1

Deltaic

ShelClastic

ShelCarbonate

Strandp

lain

Ree

FluvialDeltaic

Eo

lian

Fluvial&Alu

vial

Turbidite

Coal

Basalt(LIP)

Notes:

The number in the cell is the number of investigations per depositional environment.

Large Scale Field Tests Injection of over 1,000,000 tons of CO2.

Small Scale Field Tests Injection of less than 500,000 tons of CO2.

Site Characterization Characterize the subsurface at a location with the potential to inject at least 30,000,000 tons of CO2.

Reservoir potentials were inferred from petroleum industry data and field data from the sequestration program.

Executive Summary

A need exists or urther research on carbon storage

technologies to capture and store carbon dioxide (CO2)

rom stationary sources that would otherwise be emitted

to the atmosphere. Carbon capture and storage (CCS)technologies have the potential to be a key technology

or reducing CO2

emissions and mitigating global climate

change.

Deploying these technologies on a commercial-scale

will require geologic storage ormations capable o:

(1) storing large volumes o CO2; (2) receiving CO

2at an

eicient and economic rate o injection; and (3) saely

retaining CO2

over extended periods. Eleven major

types o depositional environments, each having their

own unique opportunities and challenges, are being

considered by the U.S. Department o Energy (DOE) orCO

2storage. The dierent classes o reservoirs reviewed

in this study include: deltaic, coal/shale, luvial, alluvial,

strandplain, turbidite, eolian, lacustrine, clastic shel,

carbonate shallow shel, and ree. Basaltic interlow

zones are also being considered as potential reservoirs.

DOE has recently completed this study which investigated

the geology, geologic reservoir properties and conining

units, and geologic depositional systems o potential

reservoirs and how enhanced oil recovery (EOR) and

coalbed methane (CBM) are currently utilizing CO2. The

study looked at the classes o geologic ormations, and

their potential to serve as CO2

reservoirs, distribution,

and potential volumes.

This study discussed the eorts that DOE is supporting to

characterize and test small- and large-scale CO2

injection

into these dierent classes or reservoirs. These tests are

important to better understand the directional tendencies

imposed by the depositional environment that may

inluence how luids low within these systems today, and

how CO2

in geologic storage would be anticipated to low

in the uture. Although diagenesis has modiied luid low

paths during the intervening millions o years since they

were deposited, the basic architectural ramework created

during deposition remains. Geologic processes that are

working today also existed when the sediments wereinitially deposited. Analysis o modern day depositional

analogs and evaluation o core, outcrops, and well logs

rom ancient subsurace ormations give an indication o

how ormations were deposited and how luid low within

the ormation is anticipated to low.

The distribution o the dierent depositional environments

that NETL is investigating is presented below. The ield

activities are in various stages o investigation with

Executive Summary


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some completed and others just underway. Additional

investigations, including small- and large-scale injection

tests, will be needed to be completed on all o the dierent

depositional environments. This will provide the inormation

on the behavior and low o CO2

in the dierent reservoirs.

Reerring to the Distribution o Field Activities or CCS/

Geologic Storage matrix, characterization has not been

completed or a shel clastic, ree, and coal environments.

Small-scale injection tests (1,000,000 tons o CO2) have not been perormed on

deltaic, strandplain, shel carbonate, eolian, turbidite,

basalt Large Igneous Providences (LIP), and coal. Three

highly experimental reservoirs that are not included on

the matrix because they have not been investigated are

ractured shales, Mid Oceanic Ridge Basalts (MORB), andoshore turbidites.

Understanding the impacts o dierent reservoir

depositional classes on storage o CO2will support DOEs

eorts to develop the knowledge and tools necessary or

uture commercialization o carbon storage technologies

throughout the United States.

1.0 Introduction and Background

Geology

Geologic storage o CO2

is a complex issue involving a

number o variables, including capturing the greenhouse

gas (GHG) emissions rom stationary sources, developing

the inrastructure to transport the CO2, and selecting

underground reservoirs or CO2

storage. This desk

reerence is based in part on a DOE report, titled,

Depositional Systems or CO2

Geosequestration (DOE/

NETL-2009/1334 Olsen et al., 2009).

This desk reerence is intended to:

Assist with an understanding of basic geological

principles and terminology associated with potential

CO2

geologic storage in ormations.

Show the importance of geologic depositional

systems in determining the internal architecture o

such ormations, thus making it possible to predict

the behavior o the injected CO2.

Establish the importance of using the geologica

depositional system to assess existing and uture

research, design, and demonstration (RD&D) needs

related to storing CO2

in dierent depositiona

environments.

A goal o DOEs Research and Development (R&D)

program in carbon storage is to classiy the

depositional environments o various ormations that

are known to have excellent reservoir properties and

are amenable to geologic CO2

storage. Using lessons

learned rom the behavior o CO2

in reservoirs rom

previous geologic investigations and their known

depositional environments is important in developing

an understanding or similar depositional environments

being considered or storage, and predicting the

expected behavior o CO2

within these proposed

reservoirs without having to duplicate the time, eortand unds that were expended on the original projects

This is being accomplished through the implementation

o 28 CO2

injection ield projects in collaboration with

the Regional Carbon Sequestration Partnership (RCSP)

Initiative and 10 American Recovery and Reinvestment

Act o 2009 (Recovery Act) projects that are ocused

on the characterization o geologic ormation as sites

or possible commercial carbon capture and storage

(CCS) development. DOE has completed this review o

geologic depositional classiication system to bette

understand how the ield work being conducted

today ulills the need to test these dierent classes o

depositional systems and determine what uture R&D

projects are still needed.

According to the U.S. Environmental Protection Agency

(EPA), total GHG emissions were estimated at 7,100 million

metric tons (7,800 million tons) CO2

equivalent in the

United States in 2006. This estimate included CO

emissions, as well as other GHGs, such as methane (CH4)

nitrous oxide (N2O), and hydroluorocarbons (HFCs)

Annual GHG emissions rom ossil uel combustion

primarily CO2, were estimated at 5,600 million metrictons (6,200 million tons), with 3,800 million metric tons

(4,200 million tons) rom stationary sources. Carbon

dioxide stationary sources are largely related to powe

production (Carbon Sequestration Atlas o the United

States and Canada, 2008).

Carbon dioxide is a byproduct o the oxidation o

hydrocarbons and is generated rom the natura

decomposition o organic material, accelerated oxidation

1 .0 I ntrod u cti on a nd B a ckg rou nd Geol og y


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(burning o ossil hydrocarbons or biomass), and

geologic sources (e.g., volcanoes). Carbon dioxide is also

the product o decomposition o rocks, like limestone

(calcium carbonate [CaCO3]), in cement manuacturing.

Geologic storage o CO2, in underground ormations

as part o CCS, is one possible long-term/permanentstorage solution or the reduction o anthropogenic CO2

rom the atmosphere. This approach involves the capture

and stabilization o large volumes o CO2

in underground

carbon sinks (storage locations) (Baines and Worden,

2004). Some variants o these underground sinks are

shown in Figure 1-1, including the surace inrastructure

and the dierent types o reservoirs that are available.

Prior to implementing CCS, site developers and owners

will utilize the results rom existing storage projects to

develop risk assessments and business models or their

individual acilities. The existing data, developed byDOEs National Energy Technology Laboratory (NETL)

and others, will allow an individual site to be evaluated to

better deine the costs or geologic storage, determine

the type and quality o geologic sinks that are available

in the region, and evaluate the type and quality o

transportation inrastructure that is required.

NETL has pioneered and developed practices or the

evaluation, installation, and operation o CCS acilities.

These practices were developed to both help reduce the

costs o implementing CCS and to protect human health

and the environment rom adverse eects o CO2. CCS

will allow the viable use o coal-ired power plants whilehelping to stabilize climate changing CO2

emissions. Coal

uels the majority o power generation capacity in the

United States and in many other areas o the world. Coal

is an abundant domestic energy resource and the primary

source o baseload power generation in the United

States, generating 1,986 million megawatt hours (MWh) in

2008. At the 2008 rate o consumption, coal could meet

the United States needs or more than 234 years. Since

1976, coal has been the least expensive ossil uel used to

generate electricity when measured based on the cost

per British thermal unit (Btu [a unit o energy content]).

Although the cost o generating electricity rom coalhas increased, it is still lower than generating electricity

rom either natural gas or petroleum in most areas. The

number o coal-ired power plants is expected to increase

in the uture. Existing acilities can be retroitted with CCS

technology to allow or the continued use o coal without

emitting CO2

emissions into the atmosphere.

Figure 1-1. Schematic of CO2

from a Thermoelectric Power Plant and Refinery being stored in Various Geologic Formations.

(Adapted from original figure, courtesy of Dan Magee, Alberta Energy Utilities Board, Alberta Geologic Survey, 2008.)



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In the oil and natural gas industry, the injection o CO2

underground has been occurring or approximately our

decades. As discussed later in this document, CO2

is used

to extract previously unrecoverable oil and increase oil

and gas production. This has resulted in millions o dollars

o additional revenue to local and state economies. Inthis application, CO2

is considered a commodity.

Although it is also important to consider non-geologic

actors or successul large-scale deployment o CCS

technologies, including geographic location (source to

sink matching), economic actors, public acceptance,

and the capture portion o CCS, this report ocuses on

evaluating the depositional environment o potential

geologic reservoirs or uture CCS projects.

1.1 Geologic Background

There are three major types o rock that uture

developers o CCS projects might target or storage

ormations, including: igneous, metamorphic, and

sedimentary. Each major type o rocks was ormed

under dierent conditions, and their potential or CO2

storage varies based on the necessary criteria o:

Capacity,which is based on the porosity or openings

within a rock, oten called pore space.

Injectivity,which is dependent on the permeability

or the relative ease with which a luid or gas can

move within the pore space(s) o a rock.

Integrity, or the ability to conine a luid or gas

within a geologic unit, is o primary importance,

because without impermeable seals, luids will take

the path o least resistance and move to a lower-

pressure area, including the surace.

The answers to questions concerning capacity,

injectivity, and integrity can be learned, in part, by

reservoir characterization o the ormations in the

area o the proposed geologic storage site. Reservoir

characterization is an evolving science that integrates

many dierent scientiic disciplines (geology, geophysics,

mathematical modeling, computational science, seismic

interpretation, well log and core analysis, etc.) in order to

build a conceptual model o a ormation. The decision

to select a particular geologic unit or geologic storage

usually depends on having a detailed understanding o

the reservoir characteristics and the behavior and ate o

the injected luids and their impact on the geologic strata

receiving the luids. Critical actors include: economic

analysis o the location o the site, the distance rom the

CO2 source to the site, the depth o the reservoir (whichinluences drilling and injectivity o CO2), the volume o

CO2

that the site can contain, the trapping mechanism

and sealing capacity, and the ultimate ate o the

What is Supercritical CO2?

Carbon dioxide can be stored in either a gas phase or in

a liquid (supercritical) phase. The volume to store gas in

a gas phase is huge compared to storage in the liquid

(supercritical) phase. To get CO2

into a supercritical phase

requires that the gas be compressed.

I the CO2

is injected into the reservoir as a liquid the

area near the well is cooled but at some distance rom

the wellbore the liquid takes on the temperature o the

reservoir. CO2

injected at depths below approximately

800 meters (2,600 eet) is at a pressure and temperature

that will allow the CO2

to remain as a supercritical luid.

By maintaining the pressure as presented in the igure

below, the volume required or geologic storage is a

raction o what is required or lower pressures.

Illustration of Effect of Pressure on CO2. (Image courtesy of

CO2CRC www.co2crc.com.au/imagelibrary/)



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stored CO2. Many o these issues will be aected by the

dierent classes o reservoirs that are being targeted or

injection.

Time plays an important role in the ormation o reservoirs,

because rocks have been ormed, eroded, and reormedmany times in the history o the Earth beore reaching the

present coniguration o continents and oceans. Reservoirs

are strongly aected by these changes. Processes such as

compaction o the rock, dissolving and enlarging pore

spaces, or illing these pore spaces with sediments or new

minerals rom solution alters the amount o porosity and

permeability o potential CO2

storage reservoirs.

Most CO2

geological storage targets are sedimentary

rocks (clastics and carbonates), where CO2

storage is in

the pore space between grains, which are most oten

illed with undrinkable saline water. Igneous ormations,which cover more o the Earths surace than sedimentary

ormations, oer potentially great geologic storage sites

because o their total volume both on continents and

under the oceans, but are mostly untested. Coalbeds are

a group o rocks that are considered both sedimentary

and metamorphic and have their own unique properties.

The most important storage mechanism or coal is its

preerential ability to adsorb CO2

directly on its surace.

This situation diers rom other sedimentary and igneous

ormations where the CO2

occupies the pore space. It is

anticipated that CO2 will be injected as a supercriticalluid in the majority o reservoirs. To better understand

how these rocks are ormed and their potential or CO2

storage, brie discussions o the dierent rock types are

summarized in the next three sections.

1.2 Igneous Rocks

Igneous rocks (rom the Latin ignis, ire) are ormed by

the solidiication o cooled magma (molten rock). All

rocks on Earth originated rom igneous sources. Igneous

rocks make up approximately 95% o the upper part o

the Earths crust. Elevated planetary temperatures during

the Earths ormation produced widespread melting that

continues today. The melt originates deep within the

Earth and is seen in the crust near active plate boundaries

or hot spots. Igneous rocks have unique compositions,

because the same elements orm dierent minerals

and dierent rock types based on the temperature and

pressure o the magma when they solidiy.

Figure 1-2 shows the ormation and distribution

o igneous rock at divergent plate boundaries and

subduction zones (where convergent plate boundaries

meet). The movement o these dierent plates is

called plate tectonics. The system is powered by heat

convection as hot magma moves upward toward the

Earths crust and then lows out (cools) away rom the

divergent plate boundary. Cooler rock tends to sink and

gets pulled down into large convection cells. The crust

loats on the mantle (83% o Earths volume) o melted

rocks that extends down about 2,900 kilometers.

Figure 1-2. Formation and Distribution of Igneous Rock in the Earths Crust. (Fichter, 2000.)



15/5615

There are two types o igneous rocks: intrusive and

extrusive. In particular, extrusive types oer some

unique potential or CO2

storage. Their high porosity

and mineralogy oer opportunities or high volume

storage and reactive chemistry that could convert the

CO2 into solid carbonates and essentially trap the CO2 inthe rocks orever.

IntrusiveIgneousRocks(plutonic) are ormed rom

magma that cools and solidiies within the Earth. The

most common intrusive rocks are granite (Figure 1-3),

which vary considerably in color depending on the

minerals present. These rocks may be ractured and

have low porosity and permeability, making them

unlikely targets as storage ormations.

Extrusive Igneous Rocks (volcanic igneous rock)

are produced when magma exits and cools quicklyoutside o, or near, the Earths surace. The quickcooling means that mineral crystals do not have muchtime to grow, so these rocks have a ine-grained or

Figure 1-5. Distribution of Known Basalt Formations in the United States and Canada

(in yellow) Investigated by NETL (2008).


Figure 1-3. Cut and polished granite showing pink

and white quartz crystals and black mica.

Figure 1-4. Basalt. (Courtesy of USGS Rock Library.)


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even glassy texture. Hot gas bubbles are oten trappedin quenched lava, orming a bubbly, vesicular textureand lots o porosity. In particular, basalts (Figure 1-4)are extrusive igneous rocks that oer opportunitiesor CO

2storage. Figure 1-5 shows the geographic

extents o basalt ormations in the United States.

1.3 Metamorphic Rocks

Metamorphic rocks are ormed rom pre-existing

rocks (igneous, sedimentary, or other metamorphics).

Metamorphic rocks are created rom these pre-

existing rocks through processes that generate heat

and pressure resulting rom deep burial and tectonic

(mountain building) activity (Figures 1-6 and 1-7). For

the most part, metamorphic rocks are o little interest as

geologic targets or CO2

storage due to their low porosity

(little pore space between sediment grains) and lowpermeability (near zero interconnectivity o these pore

spaces that allows luids to low through the rock).

Figure 1-6. Slate, a fine-grained, foliated, metamorphic rock

that was formerly shale. (Courtesy of USGS Rock Library.)

Figure 1-7. Schist a metamorphic rock where heat and pressure

have elongated individual minerals. Elongated quartz crystals

are white in photo. (Courtesy of USGS Rock Library.)

However, a metamorphic rock that has some potential

or CO2

storage potential is anthracite coal. Anthracite

has progressed through three stages o coaliication.

Anthracite coal is classed as metamorphic rock, based

on the temperatures and pressures required to orm this

dense coal rom soter sedimentary coal. Anthracite isnot an abundant orm o coal and represents a relatively

small opportunity or CO2

storage.

1.4 Sedimentary Rocks

Sedimentary rocks are ormed rom ragments o pre-

existing rocks that are transported and held together

(cemented) through natural agents, such as chemical

precipitation rom solution or secretion by organisms.

Over geologic time, weathering or erosion o rock

ormations at a higher elevation produces sedimentthat is carried by water, wind, ice, and gravity to lower

elevations and deposited as sands and silts intermixed

with organic materials as sedimentary deposits. The

various environments in which this takes place are

depicted in Figure 1-8 or clastic (consisting o ragments)

rocks. A comparable schematic representation o the

depositional environments or carbonates is provided in

Figure 1-9 .

Clastics, like sandstone (Figures 1-10, 1-11, and

1-12) and shale (Figure 1-13), are deposited as

sand, silt, gravels, or with organic materials onbeaches (tidal lats, shels, and barrier islands), in

river channels (luvial), in lagoons and swamps,

in desert dunes (eolian) (Figure 1-11), in lakes

(lacustrine), or as oshore submarine ans (turbidite).

These deposits can orm ans, sand bars, deltas,

braided or meandering streams, or dunes, each

having a distinct depositional pattern and a unique

internal architecture that controls luid low within

the reservoir body (see Figure 1-8). Bituminous coal

is also an important sedimentary rock that oers

opportunities or CO2 storage and enhanced coalbedmethane (ECBM) recovery.

Carbonate rocks (Figure 1-9) are the product o

both biological and chemical systems (e.g., corals

ormed in rees, oyster shell banks, or as chemical

precipitates) (Figure 1-14). They are also classiied

as sedimentary rocks. Carbonate deposition occurs

in seawater and is highly dependent on water

depth and sunlight, which allow organisms to grow.



17/5617


Figure 1-8. Environments for Weathering and Deposition of Rocks that can Produce

Sedimentary Clastic Deposits. (Courtesy of Professor L. S. Fichter, 2000.)

Figure 1-9. Environments for Formation of Carbonate Rocks. (Courtesy of Professor

L. S. Fichter, 2000.)

Figure 1-10. Cut sandstone core (cut horizontal) from Eolian

deposit showing banding. (Courtesy of Ken Hammond, USDA

Rock Library.)

Figure 1-11. Close-up of coral pink sandstone from Eolian

formation where sand grains have been rounded and lightly

cemented together. (Courtesy of Professor Mark Wilson.)


18/5618

Most corals that are ree orming species live in

shallow water. At shallow water depths, the primary

carbonate orming species are microscopic size,

one-cell plankton. Carbonate sediments ormed

in oshore basins and in oceans are the result o

tiny shells driting down and accumulating as thick

ooze on the sealoor. The ooze is transormed into

carbonate shale or chalk over time. Carbonates also

include a subclass o rocks, called evaporates,

which include salts, gypsum, and anhydrite that are

ormed when saline water evaporates, leaving layers

o dense, low permeability salts that oten orm

seals to other high permeability ormations. Water

has reacted with carbonate rocks in some areas to

create porosity and permeability (solution channels)

making these rocks o interest or CCS.

Both clastic and carbonate rocks possess geologic

storage potential because o the relatively high porosity

and permeability developed during their ormation.

However, the unique changes that occur as sediments

are transormed into todays rock determine the exact

nature and potential o a clastic or carbonate reservoir

or luid low and storage. Changes that occur ollowing

deposition are termed post-deposition or diagenetic

changes and can impact the porosity and permeabilityo the rock and have some impacts on the injectivity,

luid low, and capacity o the ormations. Understanding

these changes and their impacts on storage is critical

to transerring the results o DOEs ield projects to

other portions United States that have similar types o

depositional environments.

Figure 1-14. Etched limestone showing shells and calcareous debris (calcium

carbonate) from Kope Formation, Ohio. (Courtesy of Jim Stuby.)


Figure 1-13. Shale with parallel bands or layers. (Courtesy of

USGS Rock Library.)

Figure 1-12. Course sandstone showing bedding planes originally

deposited horizontally. (Courtesy of USGS Rock Library.)


19/5619

During the development o the regional

characterization or geologic storage sites,

NETL through its regional carbon sequestration

partners (RCSPs) identiied and examined the

location o potential injection zones in dierent

basins throughout the United States and Canada.Initial resource estimates were calculated or

the primary storage ormations and have been

reported in the 2008 version o the Carbon

Sequestration Atlas o the United States and

Canada. These estimates are reined as NETL and

the RCSPs continue to validate storage potential

in each respective region. Conservative estimates

o storage potential in North America show the

potential or hundreds o years o CO2

storage in

deep geologic ormations bearing saline luids

and oil and gas. These geologic ormations and

reservoirs are made up o the dierent geologicclasses discussed in this report.

These sedimentary ormations contain layers o

porous or ractured rocks that are saturated with

brine, oil, and gas. Brine is a highly saline solution

that contains appreciable amounts o salts that

have either been leached rom the surrounding

rocks or rom sea water that was trapped when

the rock was ormed. The U.S. EPA has determined

that a saline ormation used or CO2

storage must

have at least 10,000 parts per million (ppm) o

total dissolved solids (TDS, - salts), compared to

sea water, which currently has approximately

34,000 ppm o TDS. Most drinking water supply

wells contain a ew hundred ppm or less o TDS.

Any higher concentrations in drinking water

would have an unacceptable, salty taste (Price,

Allen, and Unwin). Oil and gas reservoirs are

oten saline ormations that have proven traps

and seals allowing oil and gas to accumulate in a

trap over millions o years. With the exceptions o

multiple manmade wellbores, there is little reason

to believe that these same ormations would leaki the oil and gas was replaced with CO

2. Many

oil and gas ields containing stacked ormations

(dierent reservoirs) have characteristics that

make them excellent target locations or geologic

storage, including good porosity. The regions

o various sedimentary basins where saline

ormations, oil and gas ields, and unmineable

coal seams that have been assessed or storage

potential are shown in Figures 1-15 and 1-16.

Figure 1-15. Map of Oil and Gas Fields (red) Superimposed on Saline Basins

(blue) of North America. (NATCARB, 2008.)

Figure 1-16. Distribution of Known Coal Basins Investigated by NETL.

(NATCARB, 2008.)



20/5620

2.0 Characteristics of Storage

Reservoirs and Confining Units

Reservoir characterization, as applied in this report, is

based on the hypothesis that what is learned rom the

depositional environment o a reservoir can be used todevelop a geological/reservoir model. The model will

describe (in part) the characteristics and perormance

o another reservoir deposited in the same type o

depositional environment. In general, three types/

groups o reservoirs have been historically evaluated or

potential geologic storage o CO2: depleted oil and gas

reservoirs, deep coalbeds unavailable to conventional

mining, and saline ormations. Additionally, research is

being perormed to evaluate the potential or geologic

storage in ractured basalts andshales.These reservoirs

are made up o multiple depositional environments and

have been grouped together based on their reservoir

content and geology.

The characteristics o geologic ormations or reservoirs

that help make them potential geologic storage targets

include: porosity; permeability; adequate volume or

storage; seals; and a trapping mechanism(s) to conine the

CO2or sae, long-term storage. Porosity and permeability

are primarily dependent on the depositional system and

post-depositional processes or diagenesis.

Most geologic storage targets are sedimentary rocks

where CO2

storage is trapped in the pore space between

grains. Igneous ormations have great potential or CO2

because o their huge expanse, but have only recently

started to be studied as potential storage reservoirs.

Coalbeds are a group o rocks that have their own unique

properties (cleats) that control luid paths and a rock

matrix where physical adsorption in the matrix would be

the principal means o capturing CO2.

2.1 Reservoir Properties

Rocks are oten not as solid as they appear to the naked

eye. Microscopically, there are voids or pore spaces among

the sediment grains orming a rock, not unlike the space

surrounding marbles in a jar. Porosity is the irst essential

element o a reservoir, shown schematically in Figure 2-1

and microscopically in Figure 2-2. Permeability, which

involves the interconnectedness o the individual pores,

is the second essential element (Figures 2-1 and 2-2).

Permeability is the capacity o a rock to transmit luids

through interconnected pores on a microscopic scale.

Permeability depends on the size and shape o the pores,

especially the pore throats (narrow channels between

pores) that control interconnections, and the extent o

these interconnections.

2.0 Characteristics of Storage Reservoirs and Confining Units

Figure 2-1. Porosity in Rocks and Rock Permeability.


21/5621


There are predictable trends in porosity and permeability

in reservoirs related to the depositional environment

where sediments were deposited. Reservoirs associated

with delta ormations, rivers and lood plain deposits

(luvial), submarine canyons and slumpsdeltas in deep

water (turbidites), and carbonate rees are known or

their good porosity and permeability. Rock units ormed

by windblown sand (eolian) both along sea shores and in

deserts are also good reservoirs. Diagenesis over millions

o years tends to alter the trends initially established by

their depositional pattern. However, paths o luid low

ollow the path o least resistance. For the most part theyare predictable. Thus, injected CO

2would be anticipated

to abide by the reservoirs internal architecture. The

reservoir is not one large uniorm sand box, but rather has

deined boundaries and barriers initially deined by the

depositional environment in which it was deposited.

Both porosity and permeability (generation, magnitude,

and distribution) dier considerably between igneous,

metamorphic, and sedimentary (clastic and carbonate)

reservoirs. Diagenetic changes can create or destroy the

original porosity and permeability, or create barriers toluid low. Porosity, usually caused by racturing and/or

dissolution o the original rock matrix, is oten reerred

to as secondary porosity. In some cases, the secondary

porosity considerably increases the porosity o the rock

matrix and is the primary mechanism or luid storage

and luid low. Geologic storage o CO2, regardless

o other actors, must have suicient areal extent

and reservoir volume to hold large volumes, possibly

requiring several stacked ormations (oten deposited

over hundreds o thousands o years or millions o years

within the same named ormation) and their respective

trapping mechanisms and seals.

2.2 Sealing and Trapping MechanismsSince the density o CO

2is less than saline water, it tends

to loat upward; thereore, a seal (requently called the

caprock) above the storage unit is required. Seals have

to signiicantly retard the movement o luids (Couples

2005). Without a seal, hydrocarbons (oil) generated

at depth would have long ago migrated toward the

surace and either biodegraded to heavier oil or escaped

to the atmosphere. In the same manner, injected CO

will not remain in a storage reservoir unless adequate

seals are present. Analysis o seals involves assessment

o their thickness, lateral extent, permeability, andgeomechanical properties (rock mechanics), such that

their eectiveness can be quantiied. Factors that may

inluence the integrity o a caprock include lithology

(type o sediment), thickness, burial depth, ductility

Figure 2-2. Microscopic Schematic of Rock Porosity and Permeability.


22/5622


(ability to stretch or low without breaking), permeability,

and lateral continuity (Allen and Allen, 2005). Clays,

claystones, shales, chalks, and evaporites ormed by

evaporation o salt water, such as gypsum, anhydrite,

and halite, are avorable lithologies or sealing (Grunau,1987). A rock that has been drilled rom a deposit that

was laid down at the bottom o a shallow lake over a

ew tens o thousands o years is shown in Figure 2-3

(let). Individual bands o ine clay (dark brown) are

visible, as well as courser sand (light tan), a high organic

content ine sediment (decomposition o years o algae

growth - black layer), a grey/white layer o salt (the

lake dried out), ollowed by more sediment deposited

in the lake in more recent time. Fluid low would be

anticipated to low horizontally through the small zones

i the permeability is high enough but would be greatly

restricted rom moving vertically because o the bedding

plains (ine shale and anhydrite) layers. Fluid low wouldbe anticipated to be higher in the course sand layer than

in the layers composed o iner silt and clay. This shale

core, i thick enough, may be a seal or geologic storage.

Well-sorted beach sand is shown in Figure 2-3 (right)

would make an excellent reservoir; reservoirs are rarely

as uniorm except on a small scale o less than inches as

depicted with this photo.

Figure 2-3. Shale, sand, and anhydrite core from Colorado (left)and well-sorted beach sand (right). (Courtesy of USGS.)


23/5623


Figure 2-4. Capillary trapping of CO2

occurs in narrow pore

throats, which prevents the CO2

from migrating up from

the larger pores in the rock matrix. The strength of capillary

trapping depends on the width of the pore radii and on the

interfacial tension at the interface between the two fluids

(water and CO2). (CO

2Capture Project, 2009.)

Figure 2-5. Structural traps: (left) Anticline, (center) Fault, (right) Salt Dome as trap. (Modified from Petroleum Research

Institution Website, 2008.)

Trapping mechanisms are primarily stratigraphic or

structural depending on the physical processes by which

they isolate an area or ormation. Stratigraphic traps are

the result o lithology (rock type) changes. Common

stratigraphic sealing units are thick layers o shales orevaporites, which unction as hydraulic resistant seals,

as shown on microscopic level in Figure 2-4. Structural

traps can be divided into three orms: anticline trap, ault

trap, and salt dome traps. Anticline traps are ormed by

olding, causing isolation o reservoirs in high points

(Figure 2-5 let). Anticlinal traps are important in

petroleum exploration and could just as easy be or

geologic storage. Fault traps are ormed by aulting

with parallel rock sections moving so that impermeable

rock types trap the migrating luids within a reservoir

(Figure 2-5 center). Salt dome reservoirs are ormed by

salt domes or diapirs intruding into sedimentary layers

and isolating areas along the lanks o the salt structure

(Figure 2-5 right).

I both the seal and storage unit outcrops at some

extended distance rom where the CO2

is injected, the

seal may not provide containment or the time period

necessary or CO2storage.

Seals have been classiied into two main types:

Membranesealsthatrelyoncapillaryprocesses.

Hydraulic resistance sealsthatrely onlowleakage

rates (Brown, 2003).


24/5624

3.0 Depositional Environments

The majority o geologic units being considered or

geologic storage are sedimentary, having been ormed

in reshwater lakes or saline oceans, known as basins.

The current rock ormation (reservoir) architecture isthe result o millions o years o sediment deposition

in these basins. The orientation o the original deltas,

beaches, rees; how the basins were illed; and what has

happened in the intervening time since the deposition

(called diagenetic alteration) inluence the low o luids

like CO2.

Each type o geologic ormation has dierent

opportunities and challenges. While geologic ormations

are ininitely variable in detail, they have been classiied

by geologists and engineers in the petroleum industry by

their trapping mechanism, the hydrodynamic conditions(mechanical orces that produce), lithology (physical

characteristics), and more recently by their depositional

environment (how they were ormed). The depositional

environment inluences how ormation luids are held in

place, how they move, and how they interact with other

ormation luids and solids (minerals). These properties

may allow the ormation to be labeled as reservoirs,

which in a broad sense permits the containment o

liquids or gases. For the purposes o geologic storage,

the geologic ormation/reservoir classiication system

has been expanded to include unconventional reservoirs,

such as coalbeds, and igneous ormations, such as

stacked basalts. By understanding the depositional

environments o potential reservoirs, correlations can be

drawn rom similar depositional environments around

the world. This could potentially eliminate some o the

site-speciic characterization requirements or similar

depositional systems. The reservoir classiication scheme

developed or CO2

storage, based on depositional

environments, is presented as Table 3-1. For some

systems like granite an igneous rock or metamorphic

rocks there is little or no porosity or permeability except

occasional racture systems, which are oten solutionilled with other minerals, leaving them with little or no

storage potential these system are not discussed in this

document. The reservoirs internal architecture governing

low characteristics, potential chemical reactions, and

geomechanical processes rom the injection o CO2

into

dierent types o reservoir depositional environments

are summarized in Table 3-2.

For luid low in porous media, knowledge o how

depositional systems ormed and directional tendencies

imposed by the depositional environment can inluence

how luids lows within these systems today and how

CO2

in geologic storage would be anticipated to low

in the uture. Although diagenesis has modiied luidlow paths in the intervening millions o years, the basic

architectural ramework created during deposition

remains. Geologic processes that are working today also

existed when the sediments were initially deposited.

Analysis o modern day depositional analogs, evaluation

o core, outcrops, and well logs rom ancient subsurace

ormations provide an indication o how ormations

were deposited and how luid low within the ormation

is anticipated to low.

Compartmentalization is graded on how eective the

bales between adjacent areas o deposition are. This isdependent on the permeability o the material and the

amount o luid low.



25/5625

RockClassifcation

Lithology

Geoscienc

eInstituteorOilandGasRecovery

Re

searchClassifcationin1991

DOEsOilReservoir

Classifcationrom1

990s

SequestrationFormationClassifcat

ion2010

Sto

rage

Seals

Sedimentary

Clastic

Reservoirs

Delta

Delta/Fluvial-Dominated

ClassIReservoirs

De

ltaic

Delta/Wave-Dominated

Delta/Tide-Dominated

Coal/Shale

Shales

(fneterrigenousmaterialsclays

aswellasromcarbonates)

DepositedinLacustrine,Fluvia

l,Alluvial,Near

ShoreandOpenOceanMarine

Environments

Delta/Undiferentiated

Fluvial

Fluvial/BraidedStream

Class5Reservoirs

Flu

vial

Fluvial/MeanderingStream

Fluvial/Undiferentiated

AlluvialFan

Alluvial

Strandplain

Strandplain/BarrierCores

andShoreaces

Class4Reservoirs

Stran

dplain

Strandplain/BackBarriers

Strandplain/Undiferentiated

Turbidites

Slope-Basin

Class3Reservoirs

Turbidite

Basin

EolianW

indBlown:Clasticsand/orCarbonates

Eo

lian

LacustrineL

akeDeposited:Clastics,Carbonates,Evaporites

Lacu

strine

Evaporites

(romvariousLithologyDepositedinAridSettings)

Shel

Shel

Carbonate

Reservoirs

Carbonate

(>50%

Carbonate

contentbut

cancontain

Terrigenous

materials

sand,feldspar,

non-carbonate

bouldersand

evaporites)

Peritidal

Dolomitization

MassiveDissolution

Other

ShallowShel/

Open

Dolomitization

Class2Reservoirs

Shallow

Shel

MassiveDissolution

Other

ShallowShel/

Restricted

Dolomitization

MassiveDissolution

Other

Ree

Dolomitization

Ree

MassiveDissolution

Other

ShelMargin

Dolomitization

MassiveDissolution

Other

Slope-Basin

Other

Igneous

Basalts

Basaltic

Intero

wZones

Granitic

Metamorphic

Table3-1.ReservoirDepositionalClassiicationSchematic.



26/5626

Table 3-2. Characteristics of Depositional Reservoirs.

Classification

Primary Flow

Direction of

Injected Fluids

Composition

Characteristic

Deposition

Pattern

Potential CO2

Interactions

Chemical

Interactions

with CO2

Compartmentalization1

Deltaic

Parallel to

stream or deltaaxis when

deposited.

Fluids low

in high

permeability

paths

Ranges rom course

sand in channelbottoms to ine

clays in seals, but

ormed within

predictable ranges

o deposition or

types o deltas

Dependent on

delta type and

where within

delta.

Interactiondependent

on carbonate

content and

clay barrier

(shales) within

Moderate

chemical

reactivity

depending on

clays

Depends on where

in depositional

environment

Coal

Parallel to axis

o least stress

imposed by

diagenesis

on the cleat

network

Highly variable

content with

organic content

showing remains o

plant materials, as

well as various clays

and sand

Highly variable,

but deposited

in layers

Adsorption

dominates

Adsorption

dominates, but

little chemical

reactivity

Controlled by cleat

network

Shale

Flow direction

controlled bydiagenesis ater

deposition.

Little low- low

porosity and

permeability

Mostly ine tovery ine clays,

ine sand, organic

matter, and/or

ine carbonate

ragments

Deposited

as layers inlow low

environments

causing drapes

over higher

permeability

larger sediment

Forms seals

Slow chemical

reactions with

clays in shale

Few compartments,

orms seals and barriers

within and between

other ormations.

Fluvial

Parallel to axis

o stream when

deposited.

Fluids low

in high

permeability

paths

Ranges rom course

sand in channel

bottoms to ine

clays in seals, but

ormed within

predictable ranges

o deposition or

rivers

Fining upward

in channel

Interaction

dependent

on carbonate

content and

clay barrier

(shales) within

Moderate

chemical

reactivity

depending on

clays

Highly variable

depending on where

within luvial system

Alluvial

Parallel to

axis o alluvial

an when

deposited

Wide mix o

poorly sorted

materials, size, and

composition

Fan thinning to

distal end

Highly

variable

based on rock

composition

Highly variablebased on rock

composition

Little

StrandplainParallel to

beach ront

Principally quartz

sands

Parallel to the

beach and

perpendicular

to the beach

Little

interaction

Little chemical

reactivity as

mostly quartz

sand

Moderate

Turbidite

Parallel to axis

o deposition

o an

Variable

composition and

ranges rom iner

carbonate, sand,

ine clays to very

ine clays

Repeated

layers o ining

upward. Fine

materials

toward distal

end

Interaction

dependent

on carbonate

content

Chemical

reactivity

dependent

on carbonate,

quartz sand,

and clay

composition

Highly

Eolian

Parallel toprevailing

wind direction

at time o

deposition

Mostly well-

rounded quartz

sands, ew ines

Patterndepends on

dune type, but

within dune

type are usually

consistent

Little

interaction

Little chemical

reactivity as

mostly quartz

sand

Highly



27/5627

Classification

Primary Flow

Direction of

Injected Fluids

Composition

Characteristic

Deposition

Pattern

Potential CO2

Interactions

Chemical

Interactions

with CO2

Compartmentalization1

Lacustrine

Parallel tohorizontally

depositional

bedding plane

Flow direction

controlled by

diagenesis ater

deposition.

Little low

Fine clays, silt,

sand, organics,

windblown ines,

evaporites, and

carbonates

Highly layered

depositional

pattern, oten

relecting

seasonal

variations

Interaction

dependent

on carbonate,

evaporite,

and clay

content

within

Highly variable

dependent on

composition o

rock.

Highly layered

Shelf Clastic

includingBarrier Island

Highly variable

and controlled

by diagenesisater deposition

Mix o terrestrial

material (quartz,

clays, etc.) and


28/5628

nature o the deposits is dependent on the type o riverand the climate. Sediments in luvial dominated delta

environments are usually described as ining upward,

meaning that coarse sediments are on the bottom and

ine material is deposited on top. These types o deltas

tend to orm ingers o delta ront sands and the general

distribution o major sands tends to be perpendicular to

the shoreline. The lower delta plane channels become

more numerous as they divide into smaller distributaries.

Figure 3-1. Components of a Deltaic System. (Coleman and

Prior, p. 139, 1982.)

Figure 3-2. Mississippi River Delta, United States, Lobe

Development over the Last 5,000 years. (Wikipedia, 2010;

and Frasier, 1967.)

Figure 3-3. Mississippi River Delta, United States. A Recently

Developed Elongated Shaped Delta that is River-Dominated.

Photo taken by the ASTER Instrument on the Terra Satellite,

May 24, 2001. (Courtesy of NASA.)

3.1 Deltaic Reservoir Properties

Deltaic Depositional Environment

Deltas are composed o clastics, which are rock ragments

rom original geologic units that are re-deposited. There

are several groups o deltaic reservoirs, luvial (river)-

dominated, wave-dominated, tide-dominated, and

undierentiated deltas (Fowler, Rawn-Schatzinger, et al.,

1995). Each o these dierent depositional environments

will have distinctive luid low patterns due to their

internal architecture. The components o a delta

system are presented in Figure 3-1. Deltaic reservoirs

are created by stream or river ed systems that deposit

sediments rich in organic matter into standing bodies

o water (lakes, bays, lagoons, oceans, etc.), resulting

in an irregular expansion o the shoreline. These deltas

and rivers meander (move laterally) over time basedon the amount and type o deposition, river low, and

looding (Figure 3-2). In general, all deltas are marked

by a thickening wedge o sediment at the interace o

land and water. This is ormed by the rapid inlux and

deposition o sediment at a rate that exceeds its removal

and redistribution by wave and tidal action.

A luvial-dominated delta environment is associated

with streams and rivers eroding sediments and rocks,

the transportation, and deposition o sediments

(Figure 3-3). The upper delta plane is the area where

luvial, lacustrine (lake), and swamp sediments occur. The



29/5629

A tide-dominated delta is where sedimentation at

the delta ront is controlled by the high and low tides

(Figure 3-6). Multiple small-olded ridges are developed

in a linear pattern parallel to the direction o tida

currents, which may be perpendicular or parallel to the

delta ront. The lower delta plain will have extensive tida

lats where mud is deposited. The tidal-dominated delta

Other depositional eatures include levees, which

are long and narrow ridges on either side or between

streams and can develop bays between the channels.

In addition, marshes and swamps are usually extensive

between the bays and channels. The preerential low

through this depositional environment is along theancient river channels.

A wave-dominated delta environment is associated with

large waves that run over the top o spits or sand bars

and down the landward side Figure 3-4 and Figure 3-5.

The sands tend to be reworked into numerous coastal

barriers that are orientated roughly parallel to the

shoreline. Wave-dominated deltas have a broad outer

mound o beach material separated by crescent-shaped

troughs. A coarsening upward sequence is produced

through wave-dominated delta growth, but the sands o

the upper part o the sequences should show low-anglecross bedding and planar bedding through wave action

on beaches, and some onshore-directed cross bedding

rom dunes in the shoreace zone. Clear channels are

not as evident as river-dominated deltas and sediment

is deposited more parallel to the shore than away rom

the shore and the channel low is oblique or parallel to

the shore.

Figure 3-5. Rhone River, France. A Wave-Dominated

Elongated Delta. Flooding in Southern France, the

worst in decades carried sediment tinting the otherwise

black Mediterranean Sea a bright blue. (Photo from

Terre MODIS Satellite, NASA Earth Observation Collection,

December 1, 2003, courtesy of NASA.)

Figure 3-4. Nile River Delta, Egypt. A Lobe Shaped Delta

that is Wave-Dominated. North is top of image. Photo

taken from MISR Satellite, January 30, 2001. (Courtesy

of NASA.)

Figure 3-6. Ganges/Brahmaputra River Delta, Bangladesh.

This is a Tidal-Dominated Delta - the Largest Inter-Tidal

Delta in the World. North is top of image. (Photo from

MISR Satellite, November 6, 1994, courtesy of NASA.)



30/56


31/5631

adsorption capacity is based on the exposed surace

area o the coal, which is usually governed by diagenetic

processes. Coal seams tend to have low permeability

and the majority o the porosity and permeability is the

result o racturing/cleats (Figure 3-8). One issue that is

still being investigated is coal swelling in the presenceo CO2, which may reduce or cuto the low o CO

2or

methane.

Shale, the most common type o sedimentary rock, is

characterized by thin, horizontal layers o rock with low

permeability in both the horizontal and vertical direction.

Shale is composed o ine clay particles that are packed

so closely together that luids cannot move between the

particles. Clays are naturally occurring materials made

up o ine-grained minerals derived rom igneous rocks.

Fluid low is governed by ractures that could be ormed

ater deposition and other diagenetic processes. Ingeneral, vertical luid low is negligible when compared

to horizontal luid low occurring along the bedding

plane suraces. Most o the luid is transmitted along

ractures parallel to the horizontal bedding planes. In

many cases, because o the low permeability o shale

it is considered a caprock or sealing ormation or other

types o reservoirs.

Many shales contain 1 to 2% organic material in the ormo hydrocarbons, which provide an adsorption substrate

or storage similar to coal seams. Additional research

is needed to ocus on achieving economically viable

CO2

injection rates, given shales low permeability. It is

possible that this research may lead to the conclusion

that it is not easible to use ractured, organic-rich shales

as reservoirs or geologic storage.

Currently, these tight organic rich shales are being

developed as gas and oil shale plays, such as the Marcellus

Shale, and are a signiicant contributor to the domestic

natural gas resource. The shale is artiicially ractured toallow the release o the natural gas. This may provide a

potential storage reservoir or CO2

once the natural gas

has been removed.

Figure 3-8. Structure of coal and the cleat s ystem within. The frequency of

cleats is generally higher in coal than in the shale layers separating coalbeds.

Cleats provide the pathway for f luids to move through the coal. ( Tremain et al.,

1994; Dallegge and. Barker, 2009.)



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3.2 Carbonate Reservoir and Ree

Reservoir Properties

Carbonate Depositional Systems

Most carbonate material comes rom the growth anddemise o organisms that live in oceans on continental

shels. The organisms make their hard parts out o

carbonate by extracting calcium and magnesium ions,

and CO2

rom seawater. Over 90% o carbonates ormed

in modern environments are thought to be the skeletal

remains o biological organisms that ormed under

marine conditions avorable or their growth. These

conditions include light, temperature, salinity, substrate,

and presence/absence o clastics high in silicon.

The main controls on carbonate sedimentation are

tectonic movement and climate (Tucker and Wright,1990). The organisms that are the biological building

blocks o carbonate rees have speciic tolerances to

light, temperature, and water depth. Sea level changes

associated with mountain building and glaciers cause

sea transgression and regression that can control

sedimentary deposits that may cover carbonate

generating systems. The wide variety o depositional

environments possible or carbonate deposits is shown

in Figure 3-9.

Four aspects o carbonate deposition dier rom clastic

sedimentation: (1) shallow water marine carbonate

buildups are similar through geologic time; (2) they orm

in situ in shallow water with warm tropical conditions;

(3) carbonate muds are extensively preserved during

compaction; and (4) early diagenesis eects that occurjust ater deposition. Carbonate buildups have been

accumulating in dierent locations or approximately

545 million years (Demicco and Hardie, 1994).

Shapes o carbonate deposits include:

1) Isolated banks with lat tops and walls that slope

steeply down into the ocean. A modern example is

the Bahamas Bank.

2) Continental shel deposits. Modern examples are

the shelves o the Belize (Belize) and Great BarrierRee (Australia).

3) Ramp-like shelves that slope into shallow ocean

basins. A modern example is the southern shel o

the Arabian Gul.

Figure 3-9. Carbonate Depositional System. An idealized block diagram of carbonate depositional

environments based on Pennsylvanian carbonates in southeastern Utah. (Modified from Chidsey, 2007.)



33/5633

As compared to clastic sedimentation, carbonate

sedimentation is much more inluenced by aulting,

racturing, precipitation, and solution channels ater

initial deposition. In carbonates, there are ar ewer

recognizable trends in direction o luid low imposed

by the initial deposition system (ree, shallow shel, etc.).Most o the trends in luid low are the result o changes

to the rock occurring ater deposition (Budd, et al., 1995).

There are three carbonate depositional environments

that are being considered or geologic storage: Peritidal,

Shallow Shel/Open, and Shallow Shel/Restricted.

Peritidal carbonate depositional environments are

deined as the area between the highest tide to the

area exposed during the lowest tide. The term peritidal

is generally used to describe a variety o carbonate

environments associated with low-energy tidal zones,

especially tidal lats (Folk, 1973). The orientation and sizeo these depositional environments is based on the size

o the tides and the luctuation o sea levels. Ancient

peritidal carbonates commonly orm stratigraphic

traps or hydrocarbons as a result o onlap and olap

geometries, creating pinch-out structures (Shinn, 1983a).

These carbonate units have usually undergone changes

to the rock, including racturing that causes secondary

porosity.

Shallow shel open and restricted carbonates describe

the original carbonate rocks that were deposited either

in shallow waters on open shelves, restricted lagoons,

deeper water on the shel margin, or basin slopes as

precipitates. As aorementioned, changes in the rock

signiicantly impact the porosity and permeability o the

rock over time, which also aects reservoir quality both

or oil and gas accumulation and or potential capacity

as a CO2

storage reservoir. The low patterns o water

above (vadose zone) and below the water table (phreatic

zone) are shown in Figure 3-10; this is important to

understanding how secondary porosity controls luid

movement.

Reef Depositional System

The geometry o a ree basin and its tectonic history

aect the porosity, permeability, and development o

carbonate reservoirs (Klovan, 1974). Ree development

corresponds to the overall history o a basin, which is

related to tectonic movements and the rise and all o sea

level. Similar controls aect recent and ancient rees and

allow or analogies between depositional settings with

similar eatures. For example, pinnacle rees developed

in response to gradual and continual subsidence, withthe rees growing upward to obtain light as the sea leve

Figure 3-10. Groundwater zones. Flow may be through

pore network s, or fractures . Dissolution and mixing

occurs in the vadose zone and the lower phreatic zones.

(Tucker and Wright, 1990, pp 337.)



34/5634

rises. The development o pinnacle rees ound in Alberta

is illustrated in Figure 3-11. The restricted basin had

barriers that limited water circulation, which prevented

development o more massive rees that result rom

higher amounts o nutrients.

Isolated banks and rees orm on small up-aulted blocks

related to early opening o ocean basins, along the

margins o uplited continental margins, and as ringing

rees on volcanic islands. The huge ancient carbonate

continental shel that rimmed the North American

continent during the (Cambrian-Ordovician period, 100

million years BP) is an example o a shel deposit on a

stable, passive margin.

3.3 Turbidites Reservoir PropertiesTurbidite Depositional System

Turbidites are downslope gravity lows operating at

water depths o greater than 150 eet and orm slope,

shel, and basin deposits. Much like alluvial deposits that

occur at the base o many mountain ranges, these are the

subsea equivalent, but originate at the margin between

shallow water shel and deeper basins at the continental

margins, as shown in Figures 1-8 and 1-9. They can be

composed o both clastic- and carbonate-derived rock.

Major rivers do not stop at ocean boundaries, they cancontinue hundreds o miles out to sea as subsurace

rivers (turbidity lows), across the continental shel,

and travel down submarine canyons to the basin loor.

Large luvial inputs beyond river deltas are enhanced

during loods o major rivers; the larger low volume o

sediment-laden (i.e. turbid) water scours storm shels

and lagoons, becoming more and more turbid, carrying

dense, sediment-rich water into the ocean where it lows

downhill. Turbidites occur in both submarine canyons

and on the continental slope. On slopes, they can low

downslope, orming a submarine an that looks a little

like an underwater delta. The place o origin on thecontinental shel oten reills with sediment and is later

scoured o again, causing another layer to be deposited

at the base o the slope. Two dierent shaped o

turbidites are ormed based on the velocity o the low,

the sediment size, the width o the coastal plane and

the basal slope angle (Figure 3-12). Turbidites tend to

Figure 3-11. Pinnacle Reef Development in Alberta. (Alberta Energy Utility Board, 2004.)



35/5635

become stacked rom repeated sequences o deposition

down canyons or rom scouring o the continental slope

and many orm at nearly the same point o origin.

Since the low o sediment is mostly water, turbidite

sediment is well sorted when deposited on the basinloor. Turbidites can be divided into coarse-grained

(more sand) and ine-grained (more mud and less sand)

lows where the sand and mud produced dierent

sediment distribution patterns and a dierent interna

architecture as a result. As compared to many other slow

geological processes, sand and mud lowing down a

submarine canyon causes heavier sediment to all out

aster and lighter sediment to travel arther. Turbiditesthat separated rom their place o origin on the edge o

the continental slope and then deposit on the basin loo

Figure 3-12. A. Coarse-Grained, Sand-Rich Turbidite (brown) System, B. Fine-Grained, Mud-Rich Turbidite (brown) System. (Bouma, 2000.)



36/5636

are thickest at the base o the slope and thin as they move

outward into the basin (Pratson, et al., 2000). Turbidites

at the base o the submarine canyon tend to become

stacked rom repeated sequences o deposition. The

preerential luid low path within a turbidite is parallel

to the axis o the mass low (LaBlanc, 1972).

3.4 Strandplain Reservoir Properties

Strandplain Depositional System

Coastal strandplain and barrier island deposits are

laid down along a shoreline where wave and tidal

orces dominated the transport o sediments (Rawn-

Schatzinger and Lawson, 1994). Strandplains typically

are created by the redistribution o coarse sediments

by waves and long-shore currents on either side o awave-dominated delta. Tectonics and sediment supply

rate control the thickness, lateral extent, and ormation

o strandplain deposits (modern analogs are shown as

Figures 3-13 and 3-14).

Strandplain deposits are ormed by sediments moving

outward into a sea (the sea level elevation is alling). The

shoreace builds seaward and is shaped by waves and

currents, which spread out in broad continuous stacked

beach deposits along coastlines (DOE/Bartlesville

Project Oice, 1994). Two orms o strandplain sand-rich and mud-rich are distinguished by sediment

type. Sand-rich strandplain deposits are continuously

deposited parallel and perpendicular to the shoreline

and have higher permeability. The sands within mud-

rich strandplains are not continuous in the perpendicular

direction to the shoreline and have low permeability.

Lagoonal deposits (muds and ine silt that orm shale)

are usually not associated with strandplains because the

waves moved ine sediment up the coast and oten out

to sea. A strandplain with dozens o old beach ridges

seen in Figure 3-14 rom Kitikmeot Region, Nunavut,

Canada can be dated back about 10,000 years whenthe last glaciers in the area retreated. At the end o the

last glaciation, the beach level can be seen in the low,

dark cli line at the oot o the slope o the plateau. The

resulting clean sand is oten well sorted and has high

permeability and porosity. Preerential luid low is in the

direction paralleling the axis o the deposit.

Figure 3-13. Strandplain Deposit along the

South Carolina Coast (infrared satellite image).

Note the linear sand ridges building toward the

ocean as the strandplain builds through sand

brought by long-shore currents. The layered

appearance results from the accumulation

of new strandlines. (Hayes, 1989.)

Figure 3-14. Strandplain near the mouth of the Kugaryuak

River, Coronation Gulf, Southwest Kitikmeot Region, Nunavut,

Canada. (Reproduced with the permission of Natural Resources

Canada 2010, courtesy of the Geological Survey of Canada.

Photo 2002-377 by Daniel Kerr.)



37/5637

Barrier Island Depositional System

The depositional processes that inluence barrier island

ormations are a combination o wave/tidal action and

long-shore currents (DOE/Bartlesville Project Oice,

1994). Sediments are normally carried along the coast by

currents; commonly the source o the sediments is romdeltas. Wave action sorts the sediments based on grain

size and will deposit the larger sized particles on the

sea side o the barrier island irst and smaller particles

later. The deposition is based on the amount o energy

generated by tidal inluences, the strength o currents,

and the strength o the waves. During storms, iner

grained sediment may be carried up and over the barrier

island to be deposited in the mudlats and lagoons on

the land side o the barrier island.

Figure 3-15. Barrier Island with Beach and Back Dune

areas visible, South Carolina. (Photo courtesy of RichardSchatzinger, Consulting Carbonate Sedimentologist.)

Figure 3-16. Barrier Island along the Texas Coast with oceanto the left, shoreline, beach and dune ridges, mudflatsand lagoon before marshes on mainland on right of photo.(Photo Courtesy of the University of Texas.)

Two modern analogs o barrier island deposition are

shown in Figures 3-15 and 3-16. Barrier islands are easily

susceptible to storm degradation, which can erode the

sand, move the sand in the direction o the current and

waves, and overtop the island (they are unstable land

masses). Ancient barrier island deposits encounteredthe same orces (McCubbin, 1982) and preerential luid

low (highest permeability) within the (Cole, et.al., 1994

barrier island ormations is highly variable and controlled

by changes to the rock ater deposition.



38/5638

3.5 Alluvial and Fluvial Fan Reservoir

Properties

Alluvial Depositional Systems

Alluvial depositional systems, like most depositionalsystems, are gravity driven. In general, an alluvial

sediment source comes rom higher elevations, such

as mountains, and is deposited in valleys. The sediment

source and depositional l

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