Shale Oil and Gas Handbook. Theory, Technologies, and Challenges

413 Pages·2016·31.484 MB·English

by  Sohrab Zendehboudi and Alireza Bahadori (Auth.)

SHALE OIL AND GAS
HANDBOOK
Theory, Technologies, and
Challenges
SOHRAB ZENDEHBOUDI, PhD
Department of Process Engineering (Oil & Gas Program)
Faculty of Engineering and Applied Science, Memorial
University St. John’s, NL, Canada
ALIREZA BAHADORI, PhD, CEng
School of Environment, Science & Engineering, Southern
Cross University, Lismore, NSW, Australia
Managing Director of Australian Oil and Gas Services,
Pty Ltd, Lismore, NSW, Australia
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ABOUT THE AUTHORS
SohrabZendehboudi,PhD,PEng,iscurrentlyanAssistantProfessorand
StatoilChairinReservoirAnalysisDepartmentofProcessEngineering(Oil
& Gas Program), Faculty of Engineering and Applied Science, Memorial
UniversitySt.John’s,NL,Canada.Hespecializesinshaleoilandgas,process
systems,enhancedoilrecovery,andtransportphenomenainporousmedia.
Previously, he was a Post-Doctoral Fellow at Massachusetts Institute of
Technology (MIT) and the University of Waterloo, where he received
his PhD from the Department of Chemical Engineering. He earned his
MSc in Chemical Engineering from Shiraz University in Iran, ranking first
inhisclass.HereceivedaBScinChemicalEngineeringfromthePetroleum
University of Technology in Iran. Dr. Zendehboudi has taught multiple
petroleum engineering courses and has been employed by multiple oil
and gas institutions, such as the National Petrochemical Company in
Tehran, Shiraz Petrochemical Company, and the Petroleum University of
Technology. Dr. Shorab has written for multiple prestigious journals
including Elsevier’s Journal of Natural Gas Science and Engineering.
Alireza Bahadori, PhD, CEng, MIChemE, CPEng, MIEAust, RPEQ,
NER, is a research staff member in the School of Environment, Science
and Engineering at Southern Cross University, Lismore, NSW, Australia,
and managing director and CEO of Australian Oil and Gas Services, Pty.
Ltd.HereceivedhisPhDfromCurtinUniversity,Perth,WesternAustralia.
During the past 20years, Dr. Bahadori has held various process and petro-
leum engineering positions and was involved in many large-scale oil and
gas projects. His multiple books have been published by multiple major
publishers,includingElsevier.HeisaCharteredEngineer(CEng)andChar-
tered Member of the Institution of Chemical Engineers, London, UK
(MIChemE), Chartered Professional Engineer (CPEng), Chartered
Member of the Institution of Engineers Australia, Registered Professional
Engineer of Queensland (RPEQ), Registered Chartered Engineer of the
Engineering Council of United Kingdom, and Engineers Australia’s
National Engineering Register (NER).
j
xi
CHAPTERONE
Shale Gas: Introduction, Basics,
fi
and De nitions
1. INTRODUCTION
Hydrocarbonsintheformsofoilandgasphasesaretheprimaryenergy
sources which humans around the globe depend on to provide fuel for the
advanced technologies that we rely on to make our lives easier. Thus, the
demand for energy from fossil fuels is constantly on the rise to meet our
increasingly energy-intensive lifestyles [1e3].
Naturalgasisafossilfuelwhichisderivedfromlivingorganismsthatare
buriedundertheearth’scrust.Overtime,heatandpressureconverttheor-
ganismsintooilandgas.Itisoneofthecleanestandmostefficientsourcesof
energy. Due to its high calorific value and no ash content, it is widely
employed as a major fuel in several sectors such as automobile, refining,
house heating, and so on [1e3].
NaturalgashasbeenusedasanenergysourceinCanadasincethe1800s,
but it did not become a common energy source until the late 1950s.
Following the construction of the Trans Canada Pipeline, it started gaining
popularity. After the price hike of crude oil in the late 1970s, its demand
grewveryquickly.Theoilcrisisresultedinlongline-upsoutsidegasstations,
which caused decision-makers to consider natural gas. The environment
safety concern has also added to its popularity because burning of natural
gas is cleaner, compared to other fossil fuels [1e3].
Natural gas comes from both conventional and unconventional forma-
tions. The keydifferencebetween conventionaland unconventionalnatural
gases is themethod,ease,and cost associatedwithtechnology ofextraction/
production [1e3].
Shalegasisnaturalgas,oneofseveralformsofunconventionalgas.Shale
gasistrappedwithinshaleformationswithlowpermeability,whichisfine-
grained sedimentary rock. The rock acts as its source as well as a reservoir.
The shale rock appears to be the storage material and also the creator of
thegasthroughthedecompositionoforganicmatters.Therefore,thetech-
niquesusedatonewellmaynotresultinsuccessatanothershalegaslocation
[2,4,5].
ShaleOilandGasHandbook
ISBN:978-0-12-802100-2 ©2017ElsevierInc. j
http://dx.doi.org/10.1016/B978-0-12-802100-2.00001-0 Allrightsreserved. 1
2 ShaleOilandGasHandbook
Shale reserves discovered across the world consist of several billion of
tonsoftrappedoilandgas,makingthemfossilfuelresourcesofthecentury
[1,2].Itisestimatedthatapproximately456(cid:2)1012m3ofshalegasareavail-
able globally [6]. Development of economic, eco-friendly and safer drilling
technologiestoaccesstrappedgas,madeshaleresourcesthenextbigreliable
source of energy in the world, particularly in North America [7]. The US
Department of Energy projects that shale gas will occupy 50% of total en-
ergy produced in the country by 2035, that is, around 340billion cubic
meters/year [8]. In addition to the production of natural gas, other fuels like
NGLs(naturalgasliquids;propaneandbutane)aresimultaneouslyproduced
from the shale reservoirs [3,7].
The gas in many US shale formations such as Antrim shale formation
(Michigan) and New Albany Shale formation (Illinois) has been created in
the last 10,000e20,000years [9]. In 1825, the first extraction of shale gas
was performed in Fredonia (NY) in shallow and low-pressure fractures.
In naturally fractured Devonian shales, the development of the Big Sandy
gas field commenced in Floyd County, Kentucky, 1915 [10]. Until 1976,
the field extended over 1000 square miles of southern West Virginia and
into eastern Kentucky, with production from the Cleveland Shale and the
Ohio Shale, together called the “Brown Shale,” where there are 5000 wells
inKentuckyalone.Bythe1940s,tostimulatetheshalewells,explosivedown
the hole operations had been utilized. In 1965, other efficient techniques,
such as hydraulic fracturing (including 42,000 gallons of water and 50,000
pounds of sand), were developed for production wells, particularly those
withlowrecoveryrates[10].Theaverageproductionper-wellwassmallsince
the flow rate was mainly dependent on the existence of natural fractures;
however,thefieldhadafinalgasrecoveryof2(cid:2)1012ft3.Inthe1920s,there
were other widespread commercial gas production basins such as Michigan,
Appalachian, and Illinois basins in the Devonian-age shale, though the
production was typically insignificant [10].
Thediscoveryandexploitationofshaleoilandgaspresentamajorinno-
vationwitheconomicandpoliticalimplicationsfordevelopingcountries.In
recent years, the rapid expansion of shale gas development and production
has had a profound impact on the current and future of the global energy
market. The advancement of natural gas production from shell formations
is revolutionizing the energy industry in general and the oil and gas and
petrochemical sectors in particular. North America, especially the United
States of America (USA) is leading the development of this new type of
hydrocarbon resources. Innovations in extraction (or/and production)
ShaleGas:Introduction,Basics,andDefinitions 3
technologieshavemadeaccesstothesevastamountsofnaturalgasresources
technically and economically feasible.
Dependingonthedownstreamuseofthenaturalgas,shalegasmayhavea
netnegativeorpositiveimpactongreenhousegas(GHG)emissions[10e12].
In the USA, the abundance of cheap natural gas from fracking will likely
replacecoalasthepreferredfuelforenergygeneration.Thiswilllikelydecrease
the American energy sector’s GHG emissions. In other regions such as the
United Kingdom, however, natural gas might supersede fledgling renewable
energyoperationsandhaveanetnegativeimpactonclimatechange[10e12].
Astheglobalsignificanceofshalegasincreases,thereisaneedforbetter
understanding oftheshale characteristics, shale gas productionandprocess-
ing, and potential, environmental, social and economic impacts within its
value chain.
2. NATURAL GAS AND GAS RESERVOIR BASICS
Natural gas is a type of fossil fuel that forms when several layers of
buriedanimals,gases,andplants(trees)duringthousandsofyearsareexposed
tohighpressureandheat.Theinitialenergyoftheplantsoriginatedfromthe
sun is stored in natural gases in the form of chemical bonds/links [1e3]. In
general, natural gas is considered as a nonrenewable energy form as it does
not return over a fairly acceptable timeframe. Natural gas mainly includes
a high concentration of methane and low percentages of other alkanes,
hydrogen sulfide, nitrogen, and carbon dioxide. The main utilization of
natural gas is electricity generation, cooking, and heating [1e3]. Other
uses of natural gases can be raw materials for various chemicals/materials
(e.g., petrochemical products, plastics, and polymers) and car fuel. Natural
gascanonlybeusedasafuelifitisprocessedtoremoveimpurities,including
water, to meetthe specifications of marketable natural gas. The byproducts
ofthisprocessingoperationincludeethane,propane,butanes,pentanes,and
higher-molecular-weight hydrocarbons, water vapor, carbon dioxide,
hydrogen sulfide, and sometimes helium and nitrogen [1e3].
A natural gas reservoir is defined as a naturally occurring storage space
formed by rock layers such as anticline structures deep inside the earth’s
crust. These are often referred to as reservoir rocks. Reservoir rocks are
permeable and porous, to store the gases within the pores and allow them
to move through the permeable membranes. To trap natural gas, reservoir
rocksrequiretobecappedbyanimperviousrockinordertosealthestorage
area and prevent gas from escaping. Reservoir rocks are sedimentary rocks
4 ShaleOilandGasHandbook
likesandstone,arkoses,andlimestone,whichhavehighporosityandperme-
ability.Imperviousrocksarelesspermeablerocks(e.g.,shales)[1e3,13e15].
Naturally,gasisformedintwoways;eitherdirectlyfromorganicmatters
or by thermal breakdown of oil at very elevated temperatures. In addition,
formationofnatural gascanoccurthroughbacterialprocessesfromorganic
sedimentary rocks at shallow depth [1e3]. The bacteria which act on
organic substances are anaerobic in nature and the gas produced is named
biogenicgas.Thevolumeofbiogenicgasproducedperunitvolumeofsedi-
mentislower,comparedtoothertypesofnaturalgases.Biogenicgascanbe
found at depths lower than 2200ft [1e3,13e15].
Agasreservoirisformedbythenaturaloccurrenceoffourgeologicalse-
quencesatatime,namely,(1)sourcerock,(2)reservoirrock,(3)seal,and(4)
trap [1e3].
Oil and gas phases produced in source (or sedimentary) rocks migrate to
nearbyreservoirrocksandareaccumulatedduetothetrapformedbysealrocks
likeshale.Migrationtakesplacethroughpermeablemembranesandthepres-
suredifferencebetweenpores.Inthecontextoftransportphenomenainporous
media,capillarypressureplaysanimportantroleinthemovementofoilandgas.
Most reservoir rocks contain saturated water. Due to the density differ-
ence,thegasmovesupandoccupiesthespaceaboveoilsothatwaterbeing
denserremainsbelowtheoillayertocreateanaquifer.Thearrangementof
oil, gas, and water phases is depicted in Fig. 1.1 [1e3,16,17].
Figure1.1 Schematicofanoilandgasreservoir[18].
ShaleGas:Introduction,Basics,andDefinitions 5
There are two types of traps, (1) stratigraphic and (2) structural. Strati-
graphic traps form the reservoir rocks which are covered by seal rocks from
above and below like a coastal barrier island. The deposition of rock layers
isinthemannerwherereservoirrockscreateadiscontinuouslayer.Structural
trapsareformedasaresultofdeformationofrocksduetofoldingofrocklayers
and faults that occurred a long time back. The structure favors storage of oil
andgaswith a seal formedbyshale rock on the top ofthetrap[1e3,16,17].
Agasoroilresourcecanbedefinedasthetotalityofthegasoroilorig-
inallyexistingonorwithintheearth’scrustinnaturallyoccurringaccumu-
lations, and includes discovered and undiscovered, recoverable and
unrecoverable. This is the total estimate, which is irrespective of whether
the gas or oil is commercially recoverable [1e3,16,17].
“Recoverable” oil or gas refers to the portion of the total resource that
can be commercially extracted by utilizing a specific technically feasible
recoveryproject,adrillingplan,frackingprogram,andotherrelatedproject
requirements. In order to create a clearer picture of the value of these
resources, the industry breaks them into three categories [1e3]:
(cid:129) Reserves, which are discovered and commercially recoverable;
(cid:129) Contingent resources, which are discovered and potentially recoverable
but subcommercial or noneconomic in today’s costebenefit regime;
(cid:129) Prospective resources, which are undiscovered and only potentially
recoverable.
Using a similar approach to the industry, the Potential Gas Committee
(PGC), which is responsible for developing the standards for USA gas
resource assessments, also divides resources into three categories of techni-
cally recoverable gas resources, including shale gas [1e3]:
(cid:129) Probable;
(cid:129) Possible;
(cid:129) Speculative.
3. TYPES OF NATURAL GAS
Natural gas is generally categorized in two main groups in terms of
method of production and type of rock; namely conventional and uncon-
ventional [19,20].
ThedefinitionofconventionaloilandgasaccordingtotheUSDepart-
ment of Energy (EIA) is “oil and gas produced by a well drilled into a
geologic formation in which the reservoir and fluid characteristics permit
the oil and natural gas to readily flow to the wellbore.” Conventional gas
6 ShaleOilandGasHandbook
canbeextractedusingtraditionalmethodsfromreservoirswithpermeability
greater than 1millidarcies (mD) [19,21]. Currently as a result of the avail-
ability of resources and low cost of extraction, conventional gas represents
the largest share of global gas production.
Unconventionalgasontheotherhandisfoundinreservoirswithbelow
permeabilityandassuchcannotbeextractedusingconventionaltechniques.
The production process is more complex as the geological unconventional
formationshavelowpermeabilityandporosity.Theyalsocontainfluidsthat
mighthavedensityandviscosityverydifferentfromwater.(Theygenerally
have high viscosity and density.) Thus, conventional techniques cannot be
employed to produce, refine, and transport them. As a result, it costs
much more to extract unconventional petroleum, compared to conven-
tional oil and gas [19e21].
Conventionalgasistypicallyfreegastrappedinmultiple,relativelysmall,
porous zones in naturally occurring rock formations such as carbonates,
sandstones, and siltstones. The exploration and extraction of conventional
gasiseasycomparedtounconventionalgas.Unconventionalgashascompo-
sition or/and components similar to conventional natural gas. It is the un-
usual characteristics of the reservoir that contain unconventional gas. It is
also usually more difficult to produce, compared to conventional gas. Un-
conventional gas reservoirs include tight gas, coal bed methane, shale gas,
and methane hydrates [1e3,20].
Unconventional reservoirs contain much larger volumes of hydro-
carbons than conventional reservoirs [22]. Fig. 1.2 illustrates different
types of unconventional gas reservoirs in comparison with convectional
reservoirsintermsofpermeability,volume,improve,technologydevelop-
ment, and cost.
Increastiencg hvnoolluogmy,e , ihigmhprero vceodstTighCt ognavsention1alC0o0al mg1a0ds m1d md 0.1 mUdnconventional
Methane hydrates Shale gas 0.001 m0d.0001 md
Volume
Figure1.2 Comparisonofconventionalandunconventionalreservoirswithrespectto
propertiesandreservesvolume[22].
ShaleGas:Introduction,Basics,andDefinitions 7
Asexpected,shalegasisfoundinthelargestvolumesbuthasthelowest
permeability of about 0.0001mD compared to conventional which has a
permeability of 100mD [22]. According to Fig. 1.2, it is also concluded
that the cost of producing from unconventional reservoirs is much more
expensive since the formation needs to be treated in order to increase its
porosity and permeability [22].
Most of the growth in supply from current recoverable gas resources is
found in unconventional configurations. The technological improvements
in the field of drilling, especially horizontal drilling and fracturing, have
madeshalegasandotherunconventionalgassuppliescommerciallyfeasible
and have brought a revolution in the fieldof natural gas in Canada and the
USA [19,20].
Inaddition,adifferentcategorizationfornaturalgashasbeenintroduced
sothattherearevarioustypesofnaturalgasreservesbasedonthegasforma-
tion mechanisms and rock properties as follows [2,23e25]:
3.1 Biogas
The fermentation of organic matter in the absence of oxygen results in the
production of a form of gas which is called biogas. This phenomenon is
knownasananaerobicdecompositionprocess.Itoccursinlandfillsorwhere
materials such as animal waste, industrial byproducts, and sewage, are
decayed.Thistypeofgasisbiological,originatingfromlivingandnonliving
plantsandanimals.Combustionofmaterialssuchasforestresiduesresultsin
generation of a renewable energy source. In comparison with natural gas,
biogas comprises less methane, but it can be processed and then employed
as a viable energy source [2,23e25].
3.2 Deep Natural Gas
Anothertypeofunconventionalgasisdeepnaturalgas.Deepnaturalgascanbe
found in deposits at least 15,000 feet beneath the earth surface, while a
majority of conventional gas resources are just a few thousand feet deep.
Fromaneconomicalpointofview, drillingofdeepnaturalgasformationsis
not practicalinmost cases,though various methodsto produce deepnatural
gashavebeendevelopedandfurtherimprovementiscurrentlysoughtthrough
implementationofseveralresearchandengineeringactivities[2,23e25].
3.3 Shale Gas
Another category of unconventional gas is shale gas. Shale as a sedimentary
rockisfine-grainedanddoesnotdisjointinwater.Somescholarsarguethat