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Sustainability lessons from shale development in the United States for Mexico and other emerging unconventional oil and gas developers

01 Feb 2018-Renewable & Sustainable Energy Reviews (Pergamon)-Vol. 82, pp 1320-1332

AbstractMexico's recent energy reform (2013) has provided the foundations for increased private participation in attempts to offset or reverse the country's continued decline in fossil fuel production. This country is currently on path to becoming a net energy importer by 2020. Conversely, in 2015, and for the first time in over 20 years, the United States (US) became a net oil exporter to Mexico. One of the strategies being pursued by Mexico to prevent an impending supply–demand energy imbalance is the development of shale resources using horizontal drilling and hydraulic fracturing techniques. Hence, an evaluation of the inherent risks associated with hydraulic fracturing is crucial for Mexico's energy planning and decision-making process. This paper draws lessons from the recent ‘shale boom’ in the US, and it analyzes and summarizes the environmental, social, economic, and community impacts that Mexico should be aware of as its nascent shale industry develops. The analysis seeks to inform mainly Mexican policy makers, but also academics, nongovernmental organizations, and the public in general, about the main concerns regarding hydraulic fracturing activities, and the importance of regulatory enforcement and community engagement in advancing sustainability. We highlight that Mexico should only develop its unconventional resources after careful evaluation of all potential impacts and after the formulation of regulation intended for their mitigation. Furthermore, using the US as a case study, we argue that development of unconventional oil and gas resources in Mexico could lead to a short-term boom rather than to a dependable and sustainable long-term energy supply. Our analysis concludes with a set of recommendations for Mexico, featuring best practices that could be used to attenuate and address some of the impacts likely to emerge from shale oil and gas development.

Topics: Unconventional oil (58%), Energy planning (54%), Sustainability (53%), Hydraulic fracturing (52%), Oil shale (51%)

Summary (5 min read)

1. Introduction

  • With the advent of hydraulic fracturing , the use of natural gas has increased considerably.
  • While shale exploitation can provide some short-term localized economic benefits for resource-endowed nations, evidence from the US suggests these might be accompanied by a variety of environmental, social, and community-related problems [7].
  • In the US, the advent of hydraulic fracturing combined with horizontal drilling has changed the oil and gas industry dramatically [7].

1.1. Brief history of hydrocarbon development in Mexico

  • Mexico began intensive development of its hydrocarbon resources in 1904 [15].
  • The rationale advanced by the government was that oil, as an energy source, belonged to “all Mexicans,” and as such, government entities alone should exploit them for the sole purpose of benefiting the country [18].
  • This was achieved largely because of the discovery in 1979 of Cantarell, the world's third largest oilfield at the time (just behind the Ghawar and Burgan oilfields of Saudi Arabia and Kuwait).
  • This newfound bounty came with promises of jobs, technological development, commitment to industrialization, and sustainable city building.
  • By 2004, Mexico's largest oilfield had reached its maximum rate of petroleum extraction, after which it entered a state of terminal decline [20,21].

1.2. Current state of shale development in Mexico

  • The decline in hydrocarbon production has spurred support for the development of Mexico's unconventional resources as a means of reversing the situation.
  • In 2011, the US Energy Information Administration reported that Mexico has the second-largest shale gas potential in Latin America and the fourth largest globally.
  • According to a public information petition made to PEMEX in 2014, at least 924 wells have been fractured hydraulically in Mexico since 2003 [25].
  • This inconsistency highlights the urgency for transparency in information, while illustrating the pressing need for a comprehensive regulatory framework aimed at protecting the local communities and the environment.

2.1. Land impacts and issues

  • Oil and gas drilling activities require extensive use of land [27].
  • In addition to direct impacts related to land clearance, there might also be indirect effects on ecosystems near the affected area due to the “edge effect” [31].
  • Apart from issues associated with land clearance, spills of toxic oil and gas hydraulic fracturing fluids can have severe environmental impacts in neighboring areas.
  • In lieu of permanent infrastructure, many operators dig pits in the ground, line them with plastic or vinyl sheets, and use them to store water both before and after the hydraulic fracturing activity [33].
  • It is worth noting that because development is ongoing, large-scale restoration efforts do not yet exist; hence, details about the effectiveness of restoration remain vague.

2.2. Atmospheric impacts and issues

  • The main atmospheric impacts associated with hydraulic fracturing activities are related to the emissions of both greenhouse gases (primarily methane) that contribute to climate change and VOCs that affect air quality.
  • These flaring practices, which are usually a consequence of a lack of access for transportation infrastructure, cause considerable emissions that are the product of wasted resources [51].
  • The samples that surpassed the health-based risk threshold levels were 90–66,000 times the background levels for hydrogen sulfide, 30–240 times the background levels for formaldehyde, and 35–770,000 times the background levels for benzene.
  • A recent study by Loomis and Haefele [46], translated the impacts of air pollution associated with hydraulic fracturing operations into dollar terms using data from Colorado, where about one third of the state population lives on one of three major shale plays.
  • They found that the economic cost of the impact of VOCs ranges from $353 to $509 per ton emitted.

2.3. Water impacts and issues

  • The total volume of water used for hydraulic fracturing has also been at the center of much controversy because it has considerable impact on local communities in relation to its sourcing and transportation [47].
  • This is because, even after hydraulic fracturing activities have ceased, large volumes of water contaminated with toxic and hazardous materials must be managed [50].
  • They will also contain proppants and potentially radionuclides that would have to be filtered out [52,66].
  • Regarding subsurface aquifer contamination, evidence suggests faulty well construction is the most likely cause of contamination.
  • Vidic et al. [55] and Vengosh et al. [56] found little evidence of shallow-water chemical contamination; strong evidence of methane contamination; some evidence of deepwater–shallow-water aquifer mixing; and significant issues regarding produced water management and accidental spills [31].

2.4. Community impacts

  • The visual and audible impacts of oil and gas extraction are among the most common complaints communities have regarding such development [57].
  • The potential pathways to exposure to the chemicals involved in hydraulic fracturing are numerous and they include drinking water, skin contact, soil and food, and the atmosphere [60].
  • Nevertheless, studies are suggestive of potential public health risks related to HVHF activity that warrants further careful evaluation.
  • The study stressed that policymakers need to be prepared ahead of time in certain boomtown communities.
  • Moreover, Haggerty et al. [71] explored this issue and found that while communities might benefit in the short-term from booms associated with hydraulic fracturing, communities with a long-term focus on oil and gas production experienced negative effects in terms of observed income, crime, and education.

2.5. Waste management considerations

  • An exemption by the US EPA means that many forms of drilling waste are not considered hazardous; thus, they can be disposed of without special management, even though they might contain toxic materials.
  • Oil and gas extraction operations produce large volumes of water together with the oil and gas [78].
  • A study by Maloney and Yoxtheimer [84] quantified the waste produced from hydraulic fracturing operations in the state of Pennsylvania (US).
  • The main constituents of NORM are uranium, thorium, radium, and their decay products [86].

2.6. Violations (Pennsylvania case study)

  • To demonstrate the actual risks associated with operators’ practices, the authors analyzed data from Pennsylvania (US) [88].
  • Only 14,291 violations have well geolocation data (county and township).
  • A top-five environmental violation is worth US$7812/violation, with other violations being worth US$568 less (US$7244).
  • This is followed by “failure to submit well records within 30 days of completion of drilling” (US$1476/violation); “failure to install, in a permanent manner, the permit number on a completed well” (US $1617/violation); and “failure to submit annual production report,” which has no cost (US$0/violation).

2.7. Economic impacts of price volatility on unconventional oil and gas development in the United States

  • The unexpected collapse of crude oil prices in the second half of 2014 had a particularly high toll on the revenues of producers of unconventional oil and gas [89].
  • Furthermore, a decline in oil prices generally deteriorates an economy's current account and precipitates currency depreciations [96].
  • There is no evidence that operators’ incremental efficiencies have outpaced the current financial strain that many of them face across the market.
  • The oil industry continues to face challenges, with under-investment leading to stagnating production and profit (which are of special concern for oil-exporting countries that rely heavily on the oil sector) [97].

3. Mexican vulnerabilities to shale development and best practices for their mitigation

  • As is clear from this analysis, the processes associated with hydraulic fracturing have resulted in considerable damage both to the environment and to certain communities.
  • In the US, the complex cost–benefit calculations related to the development of unconventional oil and gas have resulted in intense political debate over the extent to which government should regulate such operations [99].
  • Nevertheless, public reaction to the impacts of this industry has been strong, leading to bans in some areas [13].
  • Mexico has high vulnerability to the impacts of this industry because of its specific circumstances.
  • Therefore, if development of Mexico's shale resources continues, the best practices identified in the US should be incorporated in regulatory instruments to promote impact mitigation and to advance environmental protection efforts through regulation.

3.1. Addressing land impacts through regulation

  • Mexico is one of the most biodiverse countries in the world; however, more than half its forest resources have been lost already [100].
  • Require operators to give immediate notice of any spill, fire, leak, or break to the appropriate agency followed by a full description of the event and the losses derived from it.
  • Mexico's environment has been affected seriously by ecosystem degradation.
  • Therefore, the following best practices should be considered when addressing restoration practices though regulation to ensure viable levels of ecosystem integrity are met after hydraulic fracturing operators exit the areas of extraction [110]: Establish the developer's obligation for restoration.
  • Determine the provisions for removal and filling of pits and infrastructure used to contain and store produced fluids and wastes, and the removal of all drilling supplies and equipment.

3.2. Addressing atmospheric impacts through regulation

  • The city of Monterrey, located over the Sabinas Basin, and very close to the Burgos Basin, already suffers from environmental contingencies due to poor air quality [114].
  • Establish monitoring mechanisms to ensure compliance with these set limits.
  • Require the implementation of “green completions” to reduce emissions of VOCs and associated air pollutants from well completions, by requiring developers to capture gas at the wellhead immediately after well completion, instead of releasing it into the atmosphere or flaring it off.
  • Recently, the practices of flaring and venting of gas have been increasing in Mexico.

3.3. Addressing water impacts through regulation

  • The previously analyzed requirements for water by hydraulic fracturing operations, and the water pollution avenues such operations introduce, could affect the availability of an already strained resource.
  • Require the company to perform regular water quality monitoring both in regional water bodies as well as in nearby communities.
  • Provide free and open access data to the public.
  • The following best practices should be considered to prevent subsurface contamination through well integrity [124–126].
  • Require monitoring of each well that has had well-stimulation treatment to prevent and remedy any potential breaches.

3.4. Addressing waste management concerns through regulation

  • The increase in seismic activity associated with hydraulic fracturing operations represents another source of danger for Mexico because of its inherent geological characteristics.
  • Therefore, the following best practices regarding produced water management should be considered [129–131].
  • Moreover, the requirement for monitoring of seismic activity derived from injection should be demanded to evaluate any potential impacts caused by earthquakes of relevant magnitude.
  • The US exempts waste coming from down-hole that would have otherwise been generated by contact with the oil and gas production stream during the removal of produced water or other contaminants from the products.
  • Establish hazardous waste management methods and provide for sanctions for improper management.

3.5. Enforcement recommendations

  • Regulatory Violations can result in devastating impacts on the environment and considerable risk to the health and safety of workers and the surrounding communities.
  • The Mexican maquiladora program, which spurred the industrialization of the US–Mexico border, has been deemed the main contributor to the high levels of pollution in cities on the Mexican border because of the loose enforcement of laws [136].
  • Thus, the following points should be considered when determining enforcement measures [137,138].
  • Appoint a sufficient number of inspectors to supervise and audit the practices of unconventional oil and gas developers.
  • The record should be open access and readily available via the Internet.

3.6. Community engagement recommendations

  • Public engagement is crucial in the path toward sustainable development of shale oil and gas resources.
  • In the US, it has been found that individuals living in regions that depend economically on extractive industries are likely to support hydraulic fracturing despite its numerous environmental consequences [141].
  • The following best practices should be explored when addressing community engagement and data disclosure through regulation [142,143].
  • Promote proactive notification of project proposals to ensure adequate inclusion and reach via every possible channel, including leaflet drops, radio, television, social media (e.g., Facebook, Twitter), public displays, and house calls.
  • Allow a period for information provision during which meetings should be held where operators and experts highlight the issues associated with the quality of life in areas of hydraulic fracturing development.

4. Concluding remarks

  • In the US, hydraulic fracturing outcomes have been twofold.
  • Some communities have experienced economic benefit by welcoming this industry, which has contributed to the now contested boomtown phenomenon.
  • Enforced regulation could be the difference between building an economic success and damaging the environment further, while creating serious health threats for already vulnerable communities.
  • The US’ shale development experience has served as a case study through which the authors have provided evidence of the panoply of environmental, social, and community impacts associated with hydraulic fracturing operations.
  • Therefore, as Mexico moves forward with the exploitation of its unconventional oil and gas resources, it is of utmost importance to learn from the mistakes made in the US, which occurred primarily because of the unpreparedness of the regulators.

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Title
Sustainability lessons from shale development in the United States for Mexico and other
emerging unconventional oil and gas developers
Permalink
https://escholarship.org/uc/item/97n5w4kn
Authors
Castro-Alvarez, F
Marsters, P
Ponce de León Barido, D
et al.
Publication Date
2018-02-01
DOI
10.1016/j.rser.2017.08.082
Peer reviewed
eScholarship.org Powered by the California Digital Library
University of California

Contents lists available at ScienceDirect
Renewable and Sustainable Energy Reviews
journal homepage: www.elsevier.com/locate/rser
Sustainability lessons from shale development in the United States
for Mexico and other emerging unconventional oil and gas developers
Fernando Castro-Alvarez
a,b,
, Peter Marsters
b,c
, Diego Ponce de León Barido
b,c
,
Daniel M. Kammen
b,c
a
University of California Berkeley, School of Law, 94720, USA
b
Renewable and Appropriate Energy Laboratory, University of California Berkeley, 94720, USA
c
University of California Berkeley, Energy and Resources Group, 94720, USA
ARTICLE INFO
Keywords:
Hydraulic fracturing
Mexico
Shale development
Hydrocarbons
Oil
Gas
ABSTRACT
Mexico's recent energy reform (2013) has provided the foundations for increased private participation in
attempts to oset or reverse the country's continued decline in fossil fuel production. This country is currently
on path to becoming a net energy importer by 2020. Conversely, in 2015, and for the rst time in over 20 years,
the United States (US) became a net oil exporter to Mexico. One of the strategies being pursued by Mexico to
prevent an impending supplydemand energy imbalance is the development of shale resources using horizontal
drilling and hydraulic fracturing techniques. Hence, an evaluation of the inherent risks associated with
hydraulic fracturing is crucial for Mexico's energy planning and decision-making process. This paper draws
lessons from the recent shale boom in the US, and it analyzes and summarizes the environmental, social,
economic, and community impacts that Mexico should be aware of as its nascent shale industry develops. The
analysis seeks to inform mainly Mexican policy makers, but also academics, nongovernmental organizations,
and the public in general, about the main concerns regarding hydraulic fracturing activities, and the importance
of regulatory enforcement and community engagement in advancing sustainability. Furthermore, using the US
as a case study, we argue that development of unconventional oil and gas resources in Mexico could lead to a
short-term boom rather than to a dependable and sustainable long-term energy supply. Our analysis concludes
with a set of recommendations for Mexico, featuring best practices that could be used to attenuate and address
some of the impacts likely to emerge from shale oil and gas development.
1. Introduction
With the advent of hydraulic fracturing (fracking), the use of
natural gas has increased considerably. As a result of the shale boom
in the United States (US), and the development of new fracking
technology, other countries such as China, the United Kingdom,
Turkey, Argentina, and Mexico are all evaluating the potential for
exploitation of their indigenous shale resources [14] In 2013, the US
became the largest producer of natural gas, which has led to some of
the cheapest natural gas and oil in over two decades [5]. It is estimated
that by 2020 the US will be producing 4.8 thousand barrels per day
(4.8 mb/day), which will continue to support the growth of fossil fuel
supply from regions not part of the Organization of Petroleum
Exporting Countries (OPEC) [6]. While shale exploitation can provide
some short-term localized economic benets for resource-endowed
nations, evidence from the US suggests these might be accompanied by
a variety of environmental, social, and community-related problems
[7]. Hence, the objectives of this paper are to shed light on the impacts
of hydraulic fracturing, and to provide recommendations for best
practices for consideration by Mexican policy makers as they endeavor
to succesfully regulate this industry. We summarize the literature that
explores these impacts and the best practices adopted in the US for
their mitigation, while evaluating this information in the context of
Mexico's desire to exploit its own shale resources.
In the US, the advent of hydraulic fracturing combined with horizontal
drilling has changed the oil and gas industry dramatically [7]. Since 2008,
the US has increased its production of oil and natural gas by almost 85
billion m
3
/year, and crude oil by over 3 million barrels/day [10].There
are indications the US has received short-term localized economic benets
in areas of shale development. Communities sited near shale operations
have experienced increases in employment, salaries, and per capita
income during the initial stages of such operations [9].However,the
economic instability associated with price volatility and the panoply of
environmental, social, and community impacts that emerge due to shale
http://dx.doi.org/10.1016/j.rser.2017.08.082
Received 29 April 2016; Received in revised form 12 June 2017; Accepted 22 August 2017
Corresponding author at: University of California Berkeley, School of Law, 94720, USA.
E-mail address: fcastroa@berkeley.edu (F. Castro-Alvarez).
Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx
1364-0321/ © 2017 Elsevier Ltd. All rights reserved.
Please cite this article as: Castro Alvarez, F., Renewable and Sustainable Energy Reviews (2017), http://dx.doi.org/10.1016/j.rser.2017.08.082

development, complicate decision-making processes over whether un-
conventional oil and gas resources should be developed fully. Massive
land clearing, water consumption, waste management issues, community
impacts, and emissions of greenhouse gases and volatile organic com-
pounds (VOCs) are only some of the many concerns that surround the
exploitation of unconventional resources [10].
The rapid rise in drilling activity together with the adoption of new
drilling methods in the US has meant that regulations have been slow
to catch up [11]. Consequently, controversy arose over whether the
existing oil and gas regulatory structure was suciently robust to avoid
severe environmental impacts and to protect public health [12].In
eect, the existing rules and regulations were insucient for these
purposes. However, the Federal Government largely avoided the
problem and it was left to the states to ll the regulatory gap, which
has resulted in the implementation of dierent regulatory approaches
for hydraulic fracturing across the US [13].
In the US, industry and operators have compiled considerable
information regarding hydraulic fracturing processes, but they have
usually been unwilling to disclose it given trade-secret concerns and the
competitive benets they derive from such practices [14]. Recently,
academics, nongovernmental organizations (NGOs), and the govern-
ment have all begun developing research to address the information
asymmetry that exists between developers and the public.
1.1. Brief history of hydrocarbon development in Mexico
Mexico began intensive development of its hydrocarbon resources
in 1904 [15] . At the turn of the 20th century, foreign oil companies,
mainly from the United Kingdom and the US, commenced signicant
operations that led to Mexico becoming the second-largest oil producer
in the world by the 1920s [16]. In 1938, President Lazaro Cardenas
expropriated all the assets of the foreign oil companies operating in
Mexico at the time. This action was prompted by constant threats from
these foreign companies to leave the country and take their capital if
the government forced them to sign a collective agreement with the
Petroleum Workers Union of Mexico, which, among other things,
demanded fair working conditions for the employees of the foreign
companies [17]. The rationale advanced by the government was that
oil, as an energy source, belonged to all Mexicans, and as such,
government entities alone should exploit them for the sole purpose of
beneting the country [18]. Nevertheless, Petroleos Mexicanos
(PEMEX), continued to engage in service contracts with some US oil
companies until a 1958 regulatory law implementing Article 27 of the
Mexican constitution denitively banned the practice [16].
During the 1980s, PEMEX consolidated and became one of the
main contributors to Mexico's public nances, providing around 30%
of the Federal Government's total income [19]. This was achieved
largely because of the discovery in 1979 of Cantarell, the world's third
largest oil
eld at the time (just behind the Ghawar and Burgan oilelds
of
Saudi Arabia and Kuwait). This newfound bounty came with
promises of jobs, technological development, commitment to indus-
trialization, and sustainable city building. Above all, Lopez Portillo
(and his team of experts) stressed that this windfall of wealth would be
reinvested in Mexico to guarantee a future beyond oil. However, it
took just 24 years for Cantarell to reach peak oil status. By 2004,
Mexico's largest oileld had reached its maximum rate of petroleum
extraction, after which it entered a state of terminal decline [20,21].
Since its peak in 2004, Mexico's total oil production has declined by
27%. In 2014, Mexico produced an average of 2.8 million barrels/d of
petroleum and other liquids, crude oil accounted for 2.4 million barrels
(87% of the total output), with the remainder attributable to lease
condensate, natural gas liquids, and renery processing gain. Notably,
crude oil production in 2014 was at its lowest level since 1986 and it
has continued to decline [22]. This is evidenced by the fact that during
2015 the US became a net exporter of oil to Mexico, a situation that had
not happened for over 20 years [23].
1.2. Current state of shale development in Mexico
The decline in hydrocarbon production has spurred support for the
development of Mexico's unconventional resources as a means of
reversing the situation. In 2011, the US Energy Information
Administration reported that Mexico has the second-largest shale gas
potential in Latin America and the fourth largest globally. With
technically recoverable shale resources estimated at 545 tcf of natural
gas, and 13.1 billion barrels of oil and condensate, Mexico's unconven-
tional resources are potentially larger than its proven conventional
reserves [24].
According to a public information petition made to PEMEX in
2014, at least 924 wells have been fractured hydraulically in Mexico
since 2003 [25]. These wells are in the states of Coahuila (47 wells),
Nuevo León (182 wells), Puebla (233 wells), Tabasco (13 wells),
Tamaulipas (100 wells), and Veracruz (349 wells). However, the
Proyecto Aceite Terciario del Golfo: Primera Revisión y
Recomendaciones document (prepared in 2010 by the Mexican
Ministry of Energy and National Hydrocarbons Commission) stated
that 1323 wells have been fractured hydraulically in the specic areas
of Paleocanal and Chicontepec in Veracruz and northern Puebla
[26]. This inconsistency highlights the urgency for transparency in
information, while illustrating the pressing need for a comprehensive
regulatory framework aimed at protecting the local communities and
the environment.
2. Lessons from hydraulic fracturing operations in the US
In this section, we provide a review of the literature and an analysis
of the panoply of impacts associated with hydraulic fracturing in the
US. Land impacts, atmospheric impacts, water impacts, community
impacts, public health concerns, crime considerations, waste manage-
ment, and administrative and environmental violations are evaluated.
2.1. Land impacts and issues
Oil and gas drilling activities require extensive use of land [27].
Hence, the primary major environmental impact of unconventional oil
and gas development is associated with the requirement for land. This
is estimated to be roughly 30,000 m
2
per well pad, including roads and
associated infrastructure (i.e., equivalent to about seven football elds
placed together) [28].
Hydraulic fracturing sites often intrude into forested land, agricul-
tural land, and grassland [29]. Deforestation associated with this
intrusion has been found to cause loss of habitat for animals and
plants, and to increase the impacts of climate change because of
associated land use changes [29].
The total infrastructure requirements are a function of the number
of well pads and the size of the overall development; thus, the total
impact is determined by the total number of well pads in a play [30].In
addition to direct impacts related to land clearance, there might also be
indirect eects on ecosystems near the aected area due to the edge
eect [31]. This edge eect relates to an ecosystem reducing its spatial
buer zone as a shale development encroaches.
Apart from issues associated with land clearance, spills of toxic oil
and gas hydraulic fracturing uids can have severe environmental
impacts in neighboring areas. Adams [32] focused on simulating a spill
of hydraulic fracturing uid in an experimental forest. This study found
the forest experienced signicant mortality: Two years after uid
application, 56% of the trees within the uid application area were
dead.
In lieu of permanent infrastructure, many operators dig pits in the
ground, line them with plastic or vinyl sheets, and use them to store
water both before and after the hydraulic fracturing activity [33]. These
pits can leak and subsequently kill aquatic life [34]. In addition to the
massive volumes of uids stored on site, chemicals and other additives
F. Castro-Alvarez et al.
Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx
2

involved in the hydraulic fracturing process also need to be stored and
transported safely [31].
Long-term infrastructure (usually large metal tanks with volumes of
up to several hundred barrels) generally needs to be installed to collect
the water coproduced with the oil and gas [35]. It is important to note,
however, that in extreme events such as ooding this long-term
infrastructure has been shown to fail, resulting in spills of hydraulic
fracturing uid and hydrocarbons. This was demonstrated by the 2013
oods in Colorado, which resulted in the spill of an estimated 162 m
3
of
hydrocarbons and produced water [36].
In terms of restoration (equipment removal and reseeding of the
area around a well to allow vegetation to grow back), the time
requirements and specic processes of reclamation are highly depen-
dent on the particular conditions of the well and the environmental
qualities of the area [31]. It is worth noting that because development
is ongoing, large-scale restoration eorts do not yet exist; hence, details
about the eectiveness of restoration remain vague.
2.2. Atmospheric impacts and issues
The main atmospheric impacts associated with hydraulic fracturing
activities are related to the emissions of both greenhouse gases
(primarily methane) that contribute to climate change and VOCs that
aect air quality. It is worth noting that a compounding eect is caused
by the high demands for energy associated with transportation and
electricity related to the extraction of shale oil and gas, which result in
increased local and greenhouse gas emissions [37].
The net impact of greenhouse gas emissions from hydraulic
fracturing activities is a subject of great debate that focuses on two
main issues: the emissions of greenhouse gases derived from electricity
production and the magnitude of methane leakage [38]. Methane
emissions can come from direct releases during venting or from
unintended leaks [31]. A study conducted in the DenverJulesburg
Basin (Colorado, US) found that natural gas producers lose an average
of 4% of the gas to the atmosphere, not including further losses
attributable to the pipeline and distribution system [39].
These emissions could possibly outweigh any carbon reduction
benets derived from using natural gas to replace other fossil fuels such
as coal and oil for electricity generation [38]. Tables 1 and 2, provided
by US Environmental Protection Agency (EPA), show estimates of total
annual methane emissions from oil and gas production.
During certain well operations (mainly completions, maintenance,
and some emergencies), natural gas might be burned when it cannot be
safely, protably, or practically exploited [42]. These aring practices,
which are usually a consequence of a lack of access for transportation
infrastructure, cause considerable emissions that are the product of
wasted resources [51]. The exact scale and composition of emissions
from aring vary with gas type (sour or sweet), wind speed, and aring
equipment [43].
Localized emissions can also have signicant impacts on the
community and public health. These are mainly associated with
VOCs, which are toxic precursors to ozone and include benzene,
toluene, ethylbenzene, xylenes, BTEX, and n-hexane [44]. To provide
an idea of the magnitude of the impacts related to the emission of
VOCs, we introduce the results of a study by Macey, Breech, and
Chernaik [45] . Their work analyzed the impacts on air quality specic
to the development of unconventional oil and gas in the states of
Wyoming, Arkansas, and Pennsylvania (US). They found that 16 of 35
grab samples and 14 of 41 passive samples had concentrations of VOCs
that exceeded the Agency for Toxic Substances and Disease Registry
(ATSDR) and/or EPA Integrated Risk Information System (IRIS)
threshold levels (see Table
3). The chemicals that most commonly
exceeded these threshold levels were hydrogen sulde, formaldehyde,
and benzene. Background levels of these chemicals are 0.15, 0.25, and
0.15 μg/m
3
for hydrogen sulde, formaldehyde, and benzene, respec-
tively. The samples that surpassed the health-based risk threshold
levels were 9066,000 times the background levels for hydrogen
sulde, 30240 times the background levels for formaldehyde, and
35770,000 times the background levels for benzene.
A recent study by Loomis and Haefele [46], translated the impacts
of air pollution associated with hydraulic fracturing operations into
dollar terms using data from Colorado, where about one third of the
state population lives on one of three major shale plays. They found
that the economic cost of the impact of VOCs ranges from $353 to $509
per ton emitted. Apart from VOCs, hydraulic fracturing operations are
also associated with emissions of nitrogen oxides (NOx), sulfur oxide
(SOx) and particulate matter with diameters of 2.5 µm (PM
2.5
). Loomis
and Haefele [46] found that the economic costs of NOx, SOx, and PM
2.5
emissions are $353$821, $1058$6343, and $1293$19,825 (all in
2015 dollars) per ton emitted, respectively. These signicant costs are
borne by those communities sited nearest the unconventional oil and
gas developments, regardless of whether they receive any quantiable
benet from the hydraulic fracturing operations.
Table 1
US methane emissions (Tg CO
2
Eq.), (US EPA [40]).
Activity 1990 2005 2008 2009 2010 2011 2012
Production Field Operations (Potential) 35 29 30 30 30 31 32
- Pneumatic device venting 10899999
- Tank venting 5444456
- Combustion & process upsets 2222222
- Misc. venting & fugitives 17 14 15 15 15 15 15
- Wellhead fugitives 0.5 0.4 0.5 0.5 0.5 0.5 0.5
- Production Voluntary Reductions 0 0.8 2 1 1 1 1
Production Field Operations (Net) 35 28 28 29 29 30 31
Crude Oil Transportation 0.1 0.1 0.1 0.1 0.1 0.1 0.1
Rening 0.4 0.4 0.4 0.4 0.4 0.4 0.4
Total 36 29 29 29 30 31 32
Table 2
EPA Inventory Values (US EPA [41]).
Activity Emission
Factor
Unit
Hydraulic Fracturing Completions and
Workovers that vent
41 Mg/comp or
workover
Flared Hydraulic Fracturing
Completions and Workovers
5 Mg/comp or
workover
Hydraulic Fracturing Completions and
Workovers with reduced emission
completions
3 Mg/comp or
workover
Hydraulic Fracturing Completions and
Workovers with reduced emission
completions that are
6 Mg/comp or
workover
Mg: Miligrams.
Emisssion factor: Emission factors listed in this table are for potential emissions.
Comp or workover: Completions or workovers.
F. Castro-Alvarez et al.
Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx
3

2.3. Water impacts and issues
The total volume of water used for hydraulic fracturing has also
been at the center of much controversy because it has considerable
impact on local communities in relation to its sourcing and transporta-
tion [47]. It has been estimated that a typical fractured well will
consume an average of 6 million gallons of pressurized water [48]. The
sourcing of water leads to reductions in its availability for other local
requirements. A study by the EPA found that approximately 35,000
fractured wells across the US required around 70140 billion gallons of
water per year, which is approximately equivalent to the total amount
of water used annually to support 4080 cities with a population of
50,000 inhabitants [48].
One of the primary vehicles for potential societal harm from
hydraulic fracturing is through water contamination [49]. This is
because, even after hydraulic fracturing activities have ceased, large
volumes of water contaminated with toxic and hazardous materials
must be managed [50]. If these produced waters were to enter an
aquifer in sucient concentrations, it would render the aquifer unsafe
for further use [51]. Regarding the chemical composition of these
produced waters, Engle et al. [52] concluded that while the exact
composition might vary, they will include most of the chemical
constituents that were introduced into the well, except those consumed
during the process (e.g., acids and some polymers). They will also
contain proppants and potentially radionuclides that would have to be
ltered out [52,66]. Table 4, from Hayes [53] , presents the concentra-
tions of constituents present in the owback water of a well in
Pennsylvania (US), within two weeks of it being fractured.
Regarding subsurface aquifer contamination, evidence suggests
faulty well construction is the most likely cause of contamination.
Darrah et al. [54] analyzed methane contamination within ground-
water using noble gas isotopes. They concluded that cases of contam-
ination were most likely due to poor cementing measures in the
annulus of the well. Their study also suggested that migration from
deep shales was unlikely. Sloppy cement jobs, seismic activity, or
simply poor quality cement were all cited as possible causes of
groundwater contamination. On the other hand, surface contamination
is generally caused by spills, leaks, and accidental releases. Vidic et al.
[55] and Vengosh et al. [56] found little evidence of shallow-water
chemical contamination; strong evidence of methane contamination;
some evidence of deepwatershallow-water aquifer mixing; and sig-
nicant issues regarding produced water management and accidental
spills [31].
2.4. Community impacts
The visual and audible impacts of oil and gas extraction are among
the most common complaints communities have regarding such
development [57]. As with most impacts regarding shale development,
they vary depending on the local conditions. Table 5, obtained from the
US Bureau of Reclamation [58], presents the ranges of impacts from
dierent noise sources including oil and gas development.
In addition, as evidenced in Table 6, many shale developments
cause considerable increases in tra
c with associated consequences.
Increased
levels of trac exacerbate the risk of trac accidents and
augment local air pollution emissions, while also burdening the local
community with additional wear of infrastructure. Moreover a study by
Muehlenbachs and Krupnick [59] showed that for every well drilled in
Pennsylvania (US), the number of fatal accidents in the studied county
increased by 0.6% and the number of heavy truck accidents increased
by 2%.
The potential pathways to exposure to the chemicals involved in
hydraulic fracturing are numerous and they include drinking water,
skin contact, soil and food, and the atmosphere [60]. The nature of the
damage and the risk to health are largely dependent on the concentra-
Table 3
ATSDR minimal risk levels and EPA IRIS cancer risk levels for chemicals of concern (units: μg/m
3
) (Macey, Breech, and Chernaik [45]).
Chemical ATSDR MRLs Iris Cancer Risk Levels
Acute Intermediate Chronic 1/1000,000 1/100,000 1/10,000
Benzene 29 20 10 0.45 4.5 45
1,2 butadiene x x x 0.03 0.3 3
Ethylbenzene 21700 8680 260 x x x
Formaldehyde 49 37 10 0.08 0.8 8
N-hexane x x 2115 x x x
Hydrogen sulde 98 28 x x x x
Toluene 3750 x 300 x x x
Xylenes 8680 2604 217 x x x
Table 4
Chemical composition of flowback water.
Parameter Range Median Units
pH 4.96.8 6.2 No Units
Acidity <5473 NC mg/L
Total Alkalinity 26.1121 85.2 mg/L
Hardness as CaCO3 63095,000 34,000 mg/L
Total Suspended Solids 171150 209 mg/L
Turbidity 10.51090 233 NTU
Chloride 1670
181,000
78,100 mg/L
Total Dissolved Solids 3010
261,000
1,20,000 mg/L
Specic Conductance 6800
710,000
2,56,000 micromhos/cm
Total Kjeldahl Nitrogen 5.6261 116 mg/L
Ammonia Nitrogen 3.7359 124.5 mg/L
Nitrate-Nitrite < 0.10.92 NC mg/L
Nitrite as N < 2.577.4 NC mg/L
Nitrate as N < 0.5 - < 5 NC mg/L
Biochemical Oxygen Demand 2.82070 39.8 mg/L
Chemical Oxygen Demand 22821,900 8530 mg/L
Total Organic Carbon (TOC) 1.2509 38.7 mg/L
Dissolved Organic Carbon 5695 43 mg/L
Oil & Grease (HEM) < 4.6103 NC mg/L
Cyanide, Total < 10 NC ug/L
Amenable Cyanide < 0.01 NC mg/L
Bromide 15.81600 704 mg/L
Fluoride < 0.05 - < 50 NC mg/L
Total Sulde < 3.03.2 NC mg/L
Sulte (2) 7.2
73.6 13.8 mg/L
Sulfate <1089.3 NC mg/L
Total Phosphorus < 0.12.2 NC mg/L
Total Recoverable Phenolics < 0.010.31 NC mg/L
Sulte 7.273.6 13.8 mg/L
Methylene Blue Active Sub-
stances (MBAS)
< 0.054.6 NC mg/L
Samples were collected from 17 locations.
NC - indicates the median concentration was not calculated due to undetected results.
mg/L : Miligrams per liter.
NTU: Nephelometric Turbidity Units.
F. Castro-Alvarez et al.
Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx
4

Citations
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15 Dec 2014
Abstract: Significance Previously published life cycle assessments (LCAs) of greenhouse gas emissions from the production and use of shale gas have come to widely varying conclusions about both the magnitude of emissions and its comparison with conventionally produced natural gas and coal for electricity generation. We harmonize estimates from this literature to establish more consistently derived and robust summary of the current state of knowledge. Whereas median estimates for both gas types appear less than half that of coal, alternative assumptions may lead to emissions approaching best-performing coal units, with implications for climate change mitigation strategies. Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices.

119 citations


Journal ArticleDOI
Abstract: Shale gas is becoming an increasingly promising alternative energy resource because of its high efficiency and environment-friendly characteristic. The amount of adsorbed gas on the shale matrix surfaces and dissolved gas in the shale matrix bulk is the dominant factor in the long-term productivity of shale reservoir. Although experimental measurements have been extensively carried out to investigate the gas adsorption and diffusion properties in the shale matrix, they cannot provide the detailed information on the microscopic transport mechanism of shale gas during the gas production process. Molecular simulation can accurately visualize the gas adsorption/desorption and diffusion processes in the shale matrix. In the present study, the recent research advances of molecular simulation on gas adsorption/desorption and diffusion in the shale matrix are reviewed. Firstly, the density functional theory (DFT) for shale gas molecule desorption/adsorption on the surface of the matrix crystal is illustrated. Then, the grand canonical Monte Carlo (GCMC) method predicting the amount of shale gas desorption/adsorption in the shale matrix crystal is introduced. Finally, molecular dynamics simulation (MD) for gas diffusion in the shale matrix is elucidated. Further developments of the molecular simulation method in shale gas production are also discussed.

65 citations


Journal ArticleDOI
Abstract: Shale gas, although unconventional, is a prospective clean energy source. Shale gas production is a complex multi-scale process with its spatial size ranging from the nanoscale to kilometer-scale. During shale production, the gas transport process involves the diffusion of dissolved gas molecules into the matrix bulk, desorption of adsorbed gas from the micropore surface, Knudsen diffusion and slip flow of free gas in the pore, and Darcy flow or even high-speed non-Darcy flow of free gas in the fracture network. Accordingly, understanding the shale gas transport process in the shale reservoirs poses a long-standing problem to researchers and engineers. Computational modeling offers an opportunity to effectively reveal the gas multi-scale transport mechanisms and accurately predict the amount of shale production. In this review, the shale gas transport process during shale gas production is firstly introduced. Thereafter, the multi-scale transport phenomena involving shale gas molecule desorption from the shale matrix at the atomic and molecular level, diffusion in the nanopore, diffusion and seepage into the micropore, and convection and mass flow in the mesoscopic pores and macropore are elucidated. Moreover, the corresponding multi-scale simulation models that describe the above phenomena and shale production are explained. The shale gas production genome model, which provides insights into the entire process of the shale gas production model, is proposed and clarified according to the multi-scale simulation models used in the shale gas production prediction. The shale gas production genome model is convenient for elucidating shale transport mechanisms and guiding shale gas reservoir exploitation.

64 citations


Journal ArticleDOI
Abstract: Primary oil recovery from fractured unconventional formations, such as shale or tight sands, is typically less than 10%. The development of an economically viable enhanced oil recovery (EOR) techni...

46 citations


Journal ArticleDOI
Abstract: Author(s): Rosa, L; Rulli, MC; Davis, KF; D'Odorico, P | Abstract: Shale deposits are globally abundant and widespread. Extraction of shale oil and shale gas is generally performed through water-intensive hydraulic fracturing. Despite recent work on its environmental impacts, it remains unclear where and to what extent shale resource extraction could compete with other water needs. Here we consider the global distribution of known shale deposits suitable for oil and gas extraction and develop a water balance model to quantify their impacts on local water availability for other human uses and ecosystem functions. We find that 31–44% of the world's shale deposits are located in areas where water stress would either emerge or be exacerbated as a result of shale oil or gas extraction; 20% of shale deposits are in areas affected by groundwater depletion and 30% in irrigated land. In these regions shale oil and shale gas production would likely compete for local water resources with agriculture, environmental flows, and other water needs. By adopting a hydrologic perspective that considers water availability and demand together, decision makers and local communities can better understand the water and food security implications of shale resource development.

38 citations


Cites background from "Sustainability lessons from shale d..."

  • ...8 Shale resource exploration efforts are underway in several countries, including Mexico (Castro-Alvarez et al., 2017), Algeria, Australia, Colombia, South Africa, and India (U.S. Energy Information Administration, 2015)....

    [...]

  • ...Shale resource exploration efforts are underway in several countries, including Mexico (Castro-Alvarez et al., 2017), Algeria, Australia, Colombia, South Africa, and India (U....

    [...]

  • ...Industry is using brackish groundwater resources in the Permian and Eagle Ford shale deposits (in West Texas and Texas-Mexico border regions, respectively; Scanlon et al., 2014)....

    [...]

  • ...These areas are found across the south central United States, Mexico, Argentina, northern Africa, South Africa, South Asia, and China....

    [...]

  • ...Previous studies have quantified water stress resulting from water withdrawals for hydraulic fracturing in some shale deposits in the United States, Argentina, China, and Mexico (e.g., Freyman, 2014; Galdeano et al., 2017; Guo et al., 2016; Mauter et al., 2014; Scanlon et al., 2014)....

    [...]


References
More filters


Journal ArticleDOI
17 May 2013-Science
TL;DR: Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help effectively manage water-quality risks associated with unconventional gas industry today and in the future.
Abstract: Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.

1,119 citations


Journal ArticleDOI
TL;DR: Analysis of published data reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites.
Abstract: The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources, with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified: (1) the contamination of shallow aquifers with fugitive hydrocarbon gases (i.e., stray gas contamination), which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow; (2) the contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater; (3) the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and (4) the overextraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users, particularly in water-scarce areas. Analysis of published data (through January 2014) reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself, however, remains controversial.

1,063 citations


"Sustainability lessons from shale d..." refers background in this paper

  • ...[56] found little evidence of shallow-water chemical contamination; strong evidence of methane contamination; some evidence of deepwater–shallow-water aquifer mixing; and significant issues regarding produced water management and accidental spills [31]....

    [...]


DOI
01 Jan 2018
Abstract: This memorandum documents the updates implemented in EPA’s 2020 Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI) for gathering and boosting (G&B) stations. Additional considerations for G&B were previously discussed in memoranda released November 2019 (Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2018: Updates Under Consideration for Natural Gas Gathering & Boosting Station Emissions),1 October 2018 (Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Natural Gas Gathering & Boosting Emissions),2 and April 2019 (Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates to Natural Gas Gathering & Boosting Pipeline Emissions).3

879 citations


Journal ArticleDOI
01 Jun 2011-Elements
Abstract: Development of unconventional, onshore natural gas resources in deep shales is rapidly expanding to meet global energy needs. Water management has emerged as a critical issue in the development of these inland gas reservoirs, where hydraulic fracturing is used to liberate the gas. Following hydraulic fracturing, large volumes of water containing very high concentrations of total dissolved solids (TDS) return to the surface. The TDS concentration in this wastewater, also known as “flowback,” can reach 5 times that of sea water. Wastewaters that contain high TDS levels are challenging and costly to treat. Economical production of shale gas resources will require creative management of flowback to ensure protection of groundwater and surface water resources. Currently, deep-well injection is the primary means of management. However, in many areas where shale gas production will be abundant, deep-well injection sites are not available. With global concerns over the quality and quantity of fresh water, novel water management strategies and treatment technologies that will enable environmentally sustainable and economically feasible natural gas extraction will be critical for the development of this vast energy source.

708 citations


"Sustainability lessons from shale d..." refers background in this paper

  • ...However, this process requires significant energy and hence, it causes considerable expense [81]....

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Frequently Asked Questions (1)
Q1. What are the contributions in "Sustainability lessons from shale development in the united states for mexico and other emerging unconventional oil and gas developers" ?

This paper draws lessons from the recent ‘ shale boom ’ in the US, and it analyzes and summarizes the environmental, social, economic, and community impacts that Mexico should be aware of as its nascent shale industry develops. Furthermore, using the US as a case study, the authors argue that development of unconventional oil and gas resources in Mexico could lead to a short-term boom rather than to a dependable and sustainable long-term energy supply.