industrial energy management
TRANSCRIPT
‘Overview on Conventional and Unconventional Natural Gas’
Submitted to:
Advisor: Prof. Dr. Jürgen Joseph
Advisor: Dipl.-Ing. Sascha Meng
by:
Mahmoud Eid, 173663
Ahmed Hussein, 173666
19th December 2012
Hochschule Offenburg
Badstraße 24, 77652 Offenburg
Department: Mechanical- and Process-Engineering
Study program: Energy Conversion and Management
Study course: Industrial Energy Management
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Abstract
Natural gas is considered one of the vital primary used energy sources in our
daily-life activities. Being one of the cleanest and safest energy sources, makes it a
real principle component of the world’s energy supply. As a mixture of other
flammable gases (Methane, Ethane, Propane and Butane), it is a real prosperous
value for a wide range of various utilizations. Since the proven world’s natural gas
reserves have been estimated to exceed the oil reserves at the same equivalent
scale, more attention have been paid for both exploration and mining technologies in
Europe and worldwide. In this seminar paper, we are going to address both
conventional and unconventional techniques that are used for natural gas exploration
and mining concerning the possible future developments and forecasts in Germany,
Europe and worldwide.
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Declaration of Authorship
We declare in lieu of an oath that the seminar paper submitted has been produced
by us without illegal help from other persons. We state that all passages which have
been taken out of publications of all means or unpublished material either whole or in
part, in words or ideas, have been marked as quotations in the relevant passage. We
also confirm that the quotes included show the extent of the original quotes and are
marked as such. We know that a false declaration will have legal consequences.
Mahmoud Eid, Ahmed Hussein
Offenburg, Januar 9, 2013
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Table of Contents
Abstract ................................................................................................. II
Declaration of Authorship ................................................................... III
Table of Contents ................................................................................ IV
List of Figures and Illustrations.......................................................... VI
List of Tables ....................................................................................... VI
List of Abbreviations ............................................................................ 1
1 Introduction ...................................................................................... 2
2 Overview of natural gas mining and the exploration of natural
gas in the world ..................................................................................... 3
3 Basics ............................................................................................... 9
3.1 What is Natural Gas? ............................................................................................... 9
3.2 Conventional Natural Gas ..................................................................................... 10
3.2.1 Exploration of Conventional Natural Gas ...................................................... 10
3.2.1.1 Geological Surveys ................................................................................... 11
3.2.1.2 Seismic Exploration .................................................................................. 12
3.2.1.3 Magnetometers ......................................................................................... 13
3.2.1.4 Gravimeters .............................................................................................. 13
3.2.1.5 Exploratory Wells ..................................................................................... 13
3.2.1.6 Logging ..................................................................................................... 13
3.2.1.7 Computer Assisted Exploration ................................................................ 15
3.2.2 Mining of Conventional Natural Gas ............................................................. 16
3.3 Unconventional Natural Gas ................................................................................. 17
Deep Natural Gas ........................................................................................... 17
Tight Natural Gas ........................................................................................... 17
Shale Natural Gas ........................................................................................... 17
Coalbed Methane ............................................................................................ 18
Geopressurized Zones .................................................................................... 18
3.3.1 Exploration of Unconventional Natural Gas .................................................. 19
3.3.1.1 Surface Geochemistry (SG) ...................................................................... 19
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3.3.1.2 Coal Microfracture Analysis .................................................................... 19
3.3.1.3 Vitrinite Reflectance ................................................................................. 20
3.3.2 Mining of Unconventional Natural Gas ......................................................... 20
3.3.2.1 Hydraulic Fracturing (Fracking) ............................................................... 20
3.3.2.2 Electric Fracturing .................................................................................... 21
3.3.2.3 Horizontal Drilling ................................................................................... 21
3.3.2.4 Enhanced Coalbed Recovery (CB recovery) ............................................ 21
4 Financial Comparison ................................................................... 22
5 Conclusion ..................................................................................... 23
6 Bibliography ................................................................................... 24
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List of Figures and Illustrations
Figure 1: World natural gas production in 2006 in m3 .......................................................... 3
Figure 2: World technically recoverable shale-gas resources ............................................... 4
Figure 3: World estimated natural gas resources in 2009 ..................................................... 5
Figure 4: Global Unconventional Natural Gas Technologies Market, 2009-2016................ 5
Figure 5: US gas production after employing unconventional gas extraction ...................... 7
Figure 6: Sources of gas production ...................................................................................... 7
Figure 7: Potential shale gas basins in Europe ...................................................................... 8
Figure 8: Seismic Sea survey............................................................................................... 12
Figure 9: A Well electric log data ....................................................................................... 14
Figure 10: CAE interface ..................................................................................................... 15
Figure 11: Hydraulic fracturing ........................................................................................... 20
Figure 12: Coalbed Recovery .............................................................................................. 21
List of Tables
Table 1: Natural gas mixture composition ............................................................................ 9
Table 2: Comparison between Conventional and Unconventional drilling ........................ 22
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List of Abbreviations
Abbreviation Definition
bcfd Billion cubic feet per day
tdf Trillion cubic feet
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1 Introduction
Considering the natural gas as an abundant energy source, an affordable
energy choice, a safe, reliable and the cleanest-burning hydrocarbon fuel, natural
gas is a foundational element in the future energy supply mix. Natural gas that is
produced from conventional (easy to produce) and unconventional (more difficult to
produce) resources is subjected to varying parameters like ease and cost of
extraction assuming an analogous exploration techniques.
Since the employment of the traditional (conventional) techniques of natural
gas extraction all over the world have been the same for decades, the
unconventional gas extraction techniques have been adopted to evolve mining in its
both conceptual and engineering senses.
Only 10 years ago, the unconventional gas was a nascent resource; now it’s a
core for a large business trends which involves it for wider commercial deployment
and more viable applications which are able to revolutionize he gas markets all over
the world
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2 Overview of natural gas mining and the exploration of natural
gas in the world
According to the Energy Information Administration EIA, the Global Oil and Gas
Exploration and Production industry is expected to generate revenue of $4.37 trillion
in 2012. This is up from $3.03 trillion in 2007 with a yielding annualized growth of
7.5%.
i
The global market for unconventional natural gas extraction technologies was
valued at nearly $61.2 billion in 2010 and nearly $61.6 billion in 2011. The market
should reach $91.3 billion in 2016 after increasing at a five-year compound annual
growth rate (CAGR) of 8.2%.
Figure 1: World natural gas production in 2006 in m3
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In the 1980s and 1990s, Mitchell Energy and Development Corporation has
announced the shale gas production by the hydraulic fracturing and the horizontal
drilling for the first time on a commercial level.
As the US is a leading world producer for shale gas by hydraulic fracturing, North
America (US and Canada) accounted for $54.8 billion in 2011 and is projected to
total $63.8 billion in 2016, a CAGR of 3.1%.
Asia/Australia was valued at $5.5 billion in 2011 and should reach nearly $19
billion in 2016 with a CAGR of 28.1% since China is already leading the whole world
in the shale gas resources.
ii
Figure 2: World technically recoverable shale-gas resources
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iii
iv
Figure 4: Global Unconventional Natural Gas Technologies Market, 2009-2016
Figure 3: World estimated natural gas resources in 2009
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Unconventional gas reservoirs are found worldwide, including onshore US,
Canada, Australia, Europe, Nigeria Russia, China, and India. Unconventional gas
production in the US reached a peak of 24 bcfd (8.6 tcf/year) in 2006, up from 14
bcfd (5.0 tcf/year) 10 years ago. With a 43 share, it is now the dominant source
natural gas production.
From an investment standpoint, conventional natural gas exploration holds more
risk. Gas reservoirs are typically smaller and/or more difficult to locate.
On the other hand, unconventional gas reservoirs can exist over a large area
penetrated by older conventional wells, reducing the exploration risk. Horizontal
drilling techniques may enhance and extend production of unconventional natural
gas.
Unconventional reservoirs exist in a self contained environment where the
productive formation may act as source, reservoir and seal. After test wells prove the
economic viability of a given area, unconventional resources can be developed on a
large scale.
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As the graph below describes, the boom in the US shale gas production in the
middle of 2010 has given a new potential for North America to dominate the World
natural gas production by the least of next 100 years.
v
BP's report went on to explain why North America will be almost completely self-
sufficient when it comes to energy by 2030, saying North America's deficiency would
become a small surplus. In 2030, more than half of North America's natural gas
supply is projected to be from shale gas and coal bed methane.
vi
Figure 5: US gas production after employing unconventional gas extraction
Figure 6: Sources of gas production
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In Germany, shale gas exploration projects exist within the states of North Rhine
Westphalia, Lower Saxony, Saxony-Anhalt, Thuringia and Baden-Wuerttemberg. In
North Rhine Westphalia, one commercial project of ExxonMobil Production
Deutschland GmbH (“ExxonMobil” or “EPMG”) aiming at the exploration of shale gas
received an authorisation. Nine requests for granting an exploration authorisation are
pending. In Lower Saxony nine exploration authorisations were granted to EMPG.
Two exploration authorisations are granted in Baden-Wuerttemberg (Three Leg
Resources) and Thuringia (BNK Petroleum) respectively. Saxony-Anhalt issued one
exploration authorisation to BNK Petroleum. In Lower Saxony ExxonMobil has drilled
five shale gas exploration wells plus an additional one in North Rhine Westphalia,
which results are currently being examined by ExxonMobil’s experts. ExxonMobil
has committed itself not to conduct any further shale gas fracturing activities until it
receives a “go-ahead” from an installed independent expert group, expected for
2012. In the other Länder test drillings are currently at a planning stage.vii
viii
Figure 7: Potential shale gas basins in Europe
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3 Basics
3.1 What is Natural Gas?
Natural gas is a fossil fuel. Like oil and coal, this means that it is, essentially,
the remains of plants and animals and microorganisms that lived millions and millions
of years ago.
Natural gas is a colorless, shapeless, and odorless flammable gas which
consists of a set of different gases in its pure form and mostly accompanied with oil
deposits. Unlike other fossil fuels, natural gas is clean-burning and emits lower levels
of potentially harmful byproducts into the air.
Table 1: Natural gas mixture composition
Gas type Symbol Percentage
Methane CH4 70-90%
Ethane C2H6
0-20% Propane C3H8
Butane C4H10
Carbon Dioxide CO2 0-8%
Oxygen O2 0-0.2%
Nitrogen N2 0-5%
Hydrogen sulphide H2S 0-5%
Rare gases A, He, Ne, Xe trace
The natural gas is said to be pure as the percentage of pure Methane within the
extracted gas is increasing. When the natural gas has the majority of Methane
content, it can be cosidered as ‘dry’, while on the other hand, when the other
hydrocarbons are contained, the natural gas is then considered to be ‘wet’.
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3.2 Conventional Natural Gas
When using the term of conventional natural gas, we typically mean an easy
and economically feasible way to extract the gas trapped (free gas) in multiple,
relatively small, porous zones in various naturally occurring rock formations such
as carbonates, sandstones, and siltstones.
The word conventional in its applicable description will closely relate to how
momentarily a certain technology has been used once ago. For example, what is
considered nowadays as conventional (due to the advance in both geological and
technological exploration knowledge), has used to be unconventional 100 years
ago when exploration of natural gas has just begun.
3.2.1 Exploration of Conventional Natural Gas
A long time ago, the only way to discover an underground petroleum and natural
gas formations was to search for surface evidence. As exploration technologies
have extremely developed in the past 20 years due to the increase of the
demand for the fossil fuel energy, the practice of locating natural gas and
petroleum deposits has been dramatically transformed.
Advanced technology and knowledge have allowed both geologists and
geophysicists to test and understand the properties of the underground rock
structures with which they could later be able to make educated guesses as to
where natural gas formations could exist. With the fact that exploration of natural
gas is actually looking for something that lies often thousands feets below the
ground, so uncertainty and complexity are twinned to the whole process.
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3.2.1.1 Geological Surveys
It is when the geologists start to examine the surface structure of the earth, and
determine where is it most likely for a natural gas deposit to be found. It has been
discovered in the 18th century, that the “anticlinal slopes” are perfect zone for
trapping natural gas formations.
These anticlinal slopes are the areas where the earth has folded up on itself
forming a dome shape void which denotes a probable existence for gas reservoirs.
With the aid of mapping and surveying, the geologists can extrapolate the location of
gas formations. Information can also be attained from the rock cuttings and
outcropping of rocks on the surface.
Once the area is specified, then comes the role of the geophysicist to map out the
underground rock formations for more detailed data.
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3.2.1.2 Seismic Exploration
Seismic technology is considered one of the most tremendous breakthroughs in
the field of natural gas exploration. Seismology simply refers to the study of how
energy waves can penetrate the earth’s crust and interacts differently with various
kinds of layers. By sending out these waves and receiving them back in a form of
vibrations, the geophysicists will be able to diagnose the properties of the geology
beneath using some kind of analogy.
Seismetic technology could also be used for exploring offshore natural gas fields
and could be used in an intelligent and mobile modules. It could also deliver highly
defined 2D, 3D and 4D images.
ix
Figure 8: Seismic Sea survey
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3.2.1.3 Magnetometers
By measuring the small differences in the Earth’s magnetic field, the
Magnetometers could also be used to measure the magnetic properties of the
underground formations which really helps for gathering data concerning the
composition of the Earth’s crust.
3.2.1.4 Gravimeters
Similar to the differences between the Earth’s magnetic fields, the gravitational
fields could also vary giving the geophysicists a better understanding for what’s in the
underground. All different underground formations and rock types have a slight
different effect on the gravitational field that surrounds the Earth. By measuring these
minute differences with very sensitive equipments, geophysicists are able to analyze
underground formations.
3.2.1.5 Exploratory Wells
The best way to stand on the fact whether a natural gas deposits are existing in a
certain given area is to dig an exploratory well. Being similar to a trial and error
approach, this operation is considered as money, effort and time consuming. On the
other hand, it is considered as the best way for the geologists to obtain solid and
reliable information about the nature of the Earth’s crust and the composition of the
underground rock layers. Also, it is a very good way for the geologists to examine the
drill cuttings and fluids to gain a better understanding of the geologic features of the
area.
3.2.1.6 Logging
Logging is simply when the drilling experts and engineers start to perform tests
during and after the drilling process. They simply monitor and log the process of the
well drilling to gain clearer picture of the rock formation and underground rock
structure. It is important also to know, that there are more than 100 different kinds of
logging.
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These 100 types include standard, electric, acoustic, radioactivity, density,
induction, caliper, directional and nuclear logging. Two of the most prolific and often
performed tests are standard logging and electric logging.
3.2.1.6.1 Standard logging
Standard logging is when the geologists start to physically examin the core
samples taken from a drilled well by using powerfull microscopes. This allows the
geologists to examine the porosity and fluid content of the subsurface rock, and to
gain a better understanding of the earth in which the well is being drilled.
3.2.1.6.2 Electric logging
Electric logging is a technique that uses the difference in the rocks’ resistance
values to monitor the difference in the properties of the different rock types. The
process is performed by lowering down an electric device that emits an electric
current and receives a resistance logging profile on a recipient for the geologists to
interpret.
x
Figure 9: A Well electric log data
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3.2.1.7 Computer Assisted Exploration
Computer assisted exploration is a technology that has taken place after the
evolution of the microprocessors and computer graphical simulation. It simply uses
the data logged by the different logging techniques and starts to develop a 3D and
4D images for the geologists to understand; visually, how the rock structures and
formations would visually look like.
xi
Figure 10: CAE interface
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3.2.2 Mining of Conventional Natural Gas
Once a potential natural gas deposit has been located, the drilling team will
start drilling a well. As it sometimes could be that the amount of the explored gas
has been wrongfully estimated, advancements have proven some successfull
techniques to reduce the drilling cost and increase its efficiency. Generally, the
drilling operation is very time and money consuming, so it could be sometimes to
happen that the amount of gas explored is not worthy enough to be extracted.
Once the gas deposit has been reached, the temperature inside the well drops
down by either the temperature difference between the well and the surface or by
using a liquid nitrogen, then the natural gas turns into a liquid phased material
which can be easily pumped to the surface and stored.
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3.3 Unconventional Natural Gas
Unconventional natural gas is a terminology that is used to describe the
natural gas deposits that are found in any other unfamiliar ways. Depth,
geological nature of the rocks, rock formations surrounding the gas deposits, the
amount and condition of gas are pretty defining whether it is a conventional or
unconventional gas finding. On an economic scale, what is easy to be extracted
can be considered as conventional, while on the other hand, what is not so easy
to be mined could be considered unconventional. Generally, there are six main
categories of unconventional natural gas which are:
Deep Natural Gas
Deep natural gas is actually that natural gas deposits that lie so deep that makes it
in contrary to the conventional ways of extraction. Normally, a conventional natural
gas deposit would lie only a few thousand feet deep under the ground, but when it
lies at a depth of 15,000 feet or more, so it is definitely an unconventional gas finding.
Tight Natural Gas
Clearly from its name, a tight natural gas is that the gas formation which lies in a
very tight underground formations and in unusual impermeable. Hardrocks,
limestones and sandstones are considered unconventional gas holders. Expensive
techniques like hydraulic fracturing and acidizing are used to release this type of
natural gas.
Shale Natural Gas
Shale deposits are formed around 350 million years ago. A shale is a very fine-
grained sedimentary rock which can be easily broken in to thin parallel layers. The
process of extracting natural gas out of shales is very expensive cause it usually
employs both horizontal drilling and hydraulic fracturing which is considered a very
complicated drilling technique.
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Coalbed Methane
Coal is another type of fossil fuel which is being extracted since a long time ago.
Since the coal is usually found in seams that run in the underground, it is usually
surrounded by natural gas either within the seam itself or the surrounding rock.
Geopressurized Zones
Geopressurized zones are these voids which are naturally found in the
underground under unusual high pressure due to their depth. These voids are formed
from layers of clay which were rapidly pressurized on the top of a porous and
absorbent material like sand or slit which acts like a mesh that separates both water
and natural gas from the clay in voids or deposits. For this operation to be done
naturally, it requires a very high depth (usually 10,000-25,000 feet) below the
surface. The combination of all these factors (high pressure and depth) makes the
extraction from these zones a very comlicated process.
Methane Hydrates
Recently and due to the exploration activities in the Arctic, a new gas formations
have been found in a frozen water cages. These water cages contain Methane which
is usually found a real interesting pure concentrations.
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3.3.1 Exploration of Unconventional Natural Gas
From the different categories mentioned above, we can conclude that the
difference between both conventional and unconventional natural gas is not the
content or the nature of the gas itself but it is all about the way the conditions of the
deposits were found and the geological surroundings containing these formations.
For example, a Seismic survey would be able to explore unconventional gas
formations only if they are contained in a recognizable amounts disregarding their
depth from the Earth’s surface (e.g. Geopressurized zones). While the Coalbed
methane could not be explored using the conventional exploration techniques,
however they could be nearer to the surface and in large amounts.
3.3.1.1 Surface Geochemistry (SG)
The surface geochemistry exploration technique simply presumes that a near-to-
surface gas formation will actively leak gas as an indicator for a subsurface gas
finding. It has been also used by some companies to explore Coalbed methane gas
formations.
3.3.1.2 Coal Microfracture Analysis
Since coal is an important source for natural gas, it is considered as a reservoir
rock. Because of its adsorption properties, a piece of coal may contain two to seven
times more gas per unit volume as a reservoir rock than a conventional gas reservoir.
In order to produce gas at economic rates, the coal should have more
cleats/fractures networks within its microscopic structure. By using computed
tomography (CT scan), quantitative images showing density and atomic number
variation can be developed, and from that, cleat development in coal can be easily
identified and hence the potential of natural gas contained.
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3.3.1.3 Vitrinite Reflectance
Vitrinite is one of the main components of coal. Explorationists have employed the
technology of Vitrinite reflectance to understand the thermal maturity of the coal
sediments and hence the rank of the Coalbeds. By analyzing the thermal conditions
and geological history of a certain area, geologists can decide whether there are a
feasible amounts of natural gas that could be found this area or not.
3.3.2 Mining of Unconventional Natural Gas
Mining of unconventional natural gas will not differ that much from the mining
techniques used for conventional gas findings except for certain conditions when the
deposits are so deep or the gas found is scattered between the rock slits and cleats.
3.3.2.1 Hydraulic Fracturing (Fracking)
Hydraulic fracturing is an artificial fracturing technique used to release the gas
trapped in the rocky or coal sediments by using highly pressurized fluids (mostly
water). Usually after finding a gas deposit in a shale and after drilling a well, water is
pumped at very high pressure that causes cracks and release the gas from the
source rocks to the reservoir rocks.
xii
Figure 11: Hydraulic fracturing
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3.3.2.2 Electric Fracturing
Similar to the hydraulic fracturing, the electric fracturing is done using an electric
gun that is inserted down along with the well dug hole and operated to release strong
electric shocks that cause cracks and release the trapped gas.
3.3.2.3 Horizontal Drilling
Horizontal drilling is one of the several types of the directional drilling technique
which follows a horizontal path. After a successful shale gas exploration is done, a
curved drilling process will begin at very high depth to start the gas extraction.
3.3.2.4 Enhanced Coalbed Recovery (CB recovery)
It is a mining technique which depends on pumping water inside the Coalbeds to
displace the scattered gas found in the rocky slits to another pipe directed to a gas
storage.
xiii
Figure 12: Coalbed Recovery
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4 Financial Comparison
The expenditure in the natural gas industry is mostly on the extraction processes
as an operational running costs. As most of the conventional natural gas formations
are easily reached by vertical drilling, so comared to the most exploited technique in
the unconventional natural gas extraction which is the horizontal drilling, it could be
considered as relatively lower in the cost. Here is a short comparison between the
vertical and horizontal drilling techniques used in conventional and unconventional
natural gas extraction respectively.
Table 2: Comparison between Conventional and Unconventional drilling
Conventional drilling Unconventional drilling
Well type Vertical Horizontal
Well pad footprint >1 acre to 3 acres 3 to 6 acres
Road construction
footprint
Similar to unconventional
drilling 5.7 acres
Water required 20,000 to 80,000 gallons 2 to 9 million gallons
Chemical required None Benzene, Xylene and Toluene
Time to drill well 1 month 3 months
Hydraulic fracturing
required Sometimes Always
Source rock Large pocket of resource;
easy to extract
Resource scattered throughout
rock, hard to extract
As we can see from the table above that the unconventional gas extractions are
far way harder than the conventional techniques, which on an operational costs level
will definitely cost more money.
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5 Conclusion
Taking into account the global boom in the unconventional natural gas exploration
and production, countries like the US, China and Russia are expected to be world
leaders in natural gas market. As it has already proven its reliability and sustainability
as a promising technology, the oil and gas corporations as well as gas producing
countries will no doubt invest more money on inventing new exploration and mining
technologies as well as developing and improving the existing techniques.
Disadvantages will also arise in the horizon of using new unconventional gas
extraction techniques, as in the USA; specially in Pennsylvania and in the last 6
years, an enormous amounts of shale gas formations have been causing some
problems that have been also accompanied with the extraction of the natural gas
from shales by fracking which led to the contamination of tab water due to the
migration of natural gas from drilled gas wells in to fresh water wells and spreading
out the diseases.
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6 Bibliography
i http://baftechnologies.com/cng/natural-gas-vehicles-around-the-world/, 17 December, 2012
ii http://www.instituteforenergyresearch.org/2012/12/06/u-s-leads-world-in-natural-gas-production-from-hydraulic-fracturing/, 17
December, 2012
iii http://www.energyrealities.org/content/non-classical-gas/erp75F6EE9A4E107B0E7, 17 December, 2012
iv http://www.bccresearch.com/report/unconventional-natural-gas-extraction-global-markets-egy087a.html, 11 December, 2012
v http://en.wikipedia.org/wiki/File:US-gas-production-1900-2011.svg, 17 December, 2012
vi http://ars.els-cdn.com/content/image/1-s2.0-S2211467X11000058-gr6.jpg, 17 December, 2012
vii http://ec.europa.eu/energy/studies/doc/2012_unconventional_gas_in_europe.pdf, 11 December, 2012
viii http://1.bp.blogspot.com/-
ndpYt5F55h4/T3dw90RSnBI/AAAAAAAAI68/trffAtBZpL8/s1600/Europe_shale_gas_resource.png, 17 December, 2012
ix http://www.iris.edu/hq/gallery/d/5956-2/SeismicWaves.jpg, 09 December, 2012
x http://www.naturalgas.org/naturalgas/exploration.asp, 09 December, 2012
xi http://www.naturalgas.org/naturalgas/exploration.asp: 09 December, 2012
xii http://www.greenerideal.com/politics/0514-vermont-takes-first-step-in-anti-fracking-legislation/, 11 December, 2012
xiii http://energy.usgs.gov/HealthEnvironment/EnergyProductionUse/ProducedWaters.aspx, 11 December, 2012