Shale gas: towards the conquest of the new extractive frontier

Shale gas: towards the conquest of the new extractive frontier

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By OPSur

Due to the rapid expansion of the shale gas industry, and the growing concern in much of the US public opinion, the EPA announced in March 2010 the launch of an in-depth investigation to account for the potential negative impacts that hydraulic fracturing technique can have on water quality and public health. Although the initial results of these studies will only be available towards the end of 2012, some states - such as New York - have already put the installation of these types of farms on hold.

In December 2010, Repsol-YPF made public the “discovery” (1) in Neuquén of 4.5 million cubic meters of “unconventional” gas, so named because it is found in special geological structures, which means that it cannot be extracted using traditional techniques. The existence of gas deposits in tight sands (tight gas) and shale gas (shale gas) has encouraged forecasts and proposals of all kinds.

In April, a report from the United States Department of Energy was released that positions Argentina as the third country in the world with “potential resources” of unconventional gas, with a possibility of recovery of 774 trillion cubic feet (TFC), behind China (1,275 TFC) and the United States (862 TFC) (, 4/18/2011).


The following month, the intentions of the governor of Neuquén, Jorge Sapag, to present to the Nation a project for the development of unconventional gas in the province, which would require an investment of US $ 10 billion, transcended. Sapag estimates that in a period of four years it would be in a position to “supply the gas that the Republic consumes, plus that which is going to be consumed by the natural growth of the industry, plus that which can be perfectly exported through the gas pipelines that are now idle to Chile and that have cost billions to build ”(La Mañana Neuquén, 3/5/2011).

The level of investment required - especially for shale gas exploration, which, unlike tight gas, necessarily involves reaching the bedrock and drilling horizontally - has revitalized the interest of the 'big players' in industry in the area, as evidenced by the landing of the North American Exxon-Mobil in Neuquén.

Now, apart from speculation and the huge business in the making, what does the exploitation of shale gas imply in strict terms? What are its potential impacts? In an attempt to answer some of these questions, we have detailed the salient aspects of Shale gas below: a provisional assessment of climate change and environmental impacts (“Shale gas: preliminary assessment of its environmental and climate change impacts”), prepared report in this regard in January 2011 by the Tyndall Center for Climate Research, an organization in the United Kingdom that brings together scientists, economists, engineers and social scientists dedicated to researching sustainable development alternatives in the face of climate change.

Hydraulic fracturing and horizontal drilling

Shale gas or shale gas is obtained from the exploitation of shale, a sedimentary rock formed from deposits of mud, silt, clay and organic matter. Formerly considered as mere formation rocks for the gas that is deposited in sandstone and carbonate reserves -which are the main objectives of conventional gas exploitation-, they have gained relevance in productive terms as a result of a favorable economic context that has triggered the price of hydrocarbons, the irreversible decline of traditional reserves, and technological advances that have allowed the combination of two techniques: horizontal drilling and hydraulic fracturing.

Hydraulic fracturing - known in English as fracking - is a reservoir stimulation technique that consists of pumping fluid and a propping agent - usually sand - at high pressure, with the purpose of producing microfractures in the storage rock of hydrocarbons. The fractures occur from the injection well and extend for hundreds of meters to the reserve rock, remaining open by the action of the propping agent, thus allowing the flow and recovery of the hydrocarbon. In turn, the horizontal drilling technique makes it possible to maximize the rocky area that, once fractured, comes into contact with the well, and consequently, to increase the extraction in terms of flow and the volume of gas that can be obtained from it. .

The use of both techniques generates differences with conventional exploitations with respect to the number and distribution of wells on the reservoirs. One of the most common ways is to build a “well pad” in the center of what are typically formations of 6 to 8 horizontal wells drilled sequentially in parallel rows. A single well, drilling vertically up to 2 km, and horizontally up to 1.2 km, removes around 140m3 of earth, so an average rig removes around 830m3, almost ten times more than a conventional well drilled 2 km deep .


Each platform can access only a small area of ​​the reservoir to be exploited, so it is common for multiple platforms to be arranged on it, and that a surface large enough is required to allow the deployment and storage of fluids and the necessary equipment for fracturing operations and horizontal drilling.


"Trade secrets"

As can be seen in Gasland (2010) –excellent documentary that records the damage caused to those living in the vicinity of this type of exploitation in the United States-, the use of chemical compounds during the hydraulic fracturing process has been the source of numerous cases. of contamination. However, based on what is known as the Halliburton amendment - as a result of the lobby exercised by that company to generate a loophole in the US energy law of 2005 - the Environmental Protection Agency (EPA, Environmental Protection Agency, in English) lacks the tools and powers to control and regulate the use of fluids in said process, allowing companies on many occasions to refuse to disclose them under the argument that they constitute “trade secrets”, as if it were the formula of the coke. For this reason, there is no precise information on the identity and concentration of the chemicals used, even when, as in New York State, it is requested as a prerequisite for project authorization.

Due to the rapid expansion of the shale gas industry, and the growing concern in much of the US public opinion, the EPA announced in March 2010 the launch of an in-depth investigation to account for the potential negative impacts that hydraulic fracturing technique can have on water quality and public health. Although the initial results of these studies will only be available towards the end of 2012, some states - such as New York - have already put the installation of these types of farms on hold.

According to the little information available to the public, although the composition of the fluid used to perform the fractures varies according to the formation to be exploited, it is generally composed of 98% water and sand, and 2% chemical additives, among which are:

  • Acid: cleans the perforation prior to injecting the fluid to perform the fractures.
  • Bactericide / biocide: inhibits the growth of organisms that could produce gases that pollute the methane gas, and reduce the ability of the fluid to transport the propping agent.
  • Clay stabilizer: prevents blocking and reduction of pore permeability by clay formations.
  • Corrosion inhibitor: reduces the formation of rust in steel pipes, well casings, etc. Reticulant: the combination of phosphate esters with metals produces a crosslinking agent that increases the viscosity of the fluid, and therefore transport more agent shoring in fractures.
  • Friction reducer: reduces friction and allows fracturing fluids to be injected at optimal doses and pressures.
  • Gelling agent: increases the viscosity of the fluid, allowing a greater transport of propping agent.
  • Metal controller: prevents the precipitation of metal oxides that could degrade the materials used.
  • Tartar inhibitor: prevents the precipitation of carbonates and sulfates (calcium carbonate, calcium sulfate, barium sulfate), which could degrade the materials used.
  • Surfactant: reduces the surface tension of the fracture fluid, and therefore helps its recovery.

According to the Tyndall Center report, the little information provided by the operators allows, even so, to certify that many substances have been classified by European control bodies as "immediate attention" due to their potential effects on health and the environment. In particular, 17 have been classified as toxic to aquatic organisms, 38 are acutely toxic, 8 are proven carcinogens and another 6 are suspected of being, 7 are mutagenic elements, and 5 produce effects on reproduction. Although the level of risk associated with the use of these substances depends on their concentration and the way in which they are exposed to living beings and the environment during their use, the enormous amounts that must be used - for a 6-well platform would range from the 1,000 and 3,500 m3 of chemicals - would, by themselves, be a motive for maximum caution and control.

Environmental and health impacts

Regardless of the contamination that could occur in a singular well, the impacts of the exploitation of shale gas deposits must be considered as a whole that involves -in addition to the processes previously described-, the movement of vehicles, the use and contamination of enormous amounts of water, noise pollution and deterioration of the landscape. These cumulative impacts must, in turn, be weighed against the fact that shale gas development on a scale sufficient to produce significant volumes involves exponentially multiplying the number of wells. Research from the Tyndall Center estimates that to maintain a production rate equivalent to 10% of UK consumption for 20 years, around 2,500-3,000 horizontal drilling would have to be carried out, in an area that could reach 400 km2, and use 113 million tons of water.

According to the report, risks and impacts can be grouped according to:

  • The contamination of groundwater by action of the fluids used for fractures, as a result of breaks in the casings or leaks;
  • The contamination of the land and surface water (and potentially groundwater), due to spills of the compounds used in the fractures, and of the contaminated waters that return to the surface once the process is concluded;
  • Overconsumption and depletion of water sources;
  • Treatment of wastewater;
  • Impacts on land and landscape;
  • The impacts derived from the construction stage of the locations, such as noise pollution during the drilling of wells, the venting of non-usable gases, and impacts due to vehicle traffic.

Flowback and underground contamination

The fracture procedure is performed sequentially, ranging from eight to thirteen stages for an average 1.2 km horizontal well. In each one of them, between 1,100 and 2,200 m3 of water are used, so in a multi-stage fracture -for a single well- between 9,000 and 29,000 m3 of water are used, and between 180 and 580 m3 of chemical additives . For all the fracturing operations carried out on a six-well platform, between 54,000 and 174,000 m3 of water are used, and between 1,000 and 3,500 m3 of chemicals. Similar quantities of water must be obtained in the place where the exploitation takes place, or failing that, transported from other locations.

Once the fracture procedure is completed, the fluid used returns to the surface - a phenomenon known in English as flowback - in proportions that vary, depending on the well, between 9% and 35%. Therefore, in each fracture process, liquid wastes ranging from 1,300 to 23,000 m3 are produced, which contain water, the chemicals used, toxic organic components, heavy metals, and natural matter with radioactive residues (called NORMs in English: Naturally Occurring Radioactive Materials). Therefore, the toxicity of the fluid that returns to the surface can be greater than that used for hydraulic fracturing, a circumstance that requires extreme care in terms of storage and wastewater treatment.

What is not recovered in the reflux process remains underground, constituting a very potential source of contamination. A possible reason may be a failure or gradual loss of well integrity, since, given the significant depth of unconventional gas reserves, these generally have to be drilled through several aquifers, which produces communication between these and other types of aquifers. formations. To reduce the risk derived from this fact, four types of casings must be made to seal the well from the adjacent formations, and to stabilize it once it is completed and in the production process. However, any eventuality that goes from a catastrophic failure of the cladding, to its progressive loss of integrity, can result in the contamination of other rock formations and groundwater, varying its consequences according to the nature of the loss of integrity, the type of pollutant and the environment in which it occurs. The greatest risk, in this sense, is an upward seepage of water used for the fracture.

Corporate reports - and even those made by various official agencies in the United States - maintain that “the probability of fracture fluids reaching any underground source of drinking water is estimated at […] less than 1 in 59 million wells [… ] so that hydraulic fracturing does not present reasonable foreseeable risks of adverse impact on potential drinking water aquifers ”(Tyndall Center, 2011: 60). However, the Tyndall Center research indicates that those studies have been based on estimates of the risk of failure in properly constructed wells, setting aside the possibility that many of them are incorrectly constructed. This is a serious omission, as any risk study should take into account possible negligence, whether intentional or not.

Indeed, hundreds of cases of contamination due to faulty or dilapidated construction and human error have been documented. "There are reports of incidents involving contamination of groundwater and surface water with contaminants such as brine [water saturated with salt], unidentified chemicals, natural gas, sulfates, and hydrocarbons such as benzene and toluene" (Tyndall Center, 2011: 62):

  • In 2004, in Garfield County, Colorado, natural gas was observed bubbling in a trough, and elevated concentrations of benzene were found in groundwater - exceeding 200 micrograms per liter in groundwater, and 90 micrograms per liter in surface areas, ninety times more than the limit established by the state. It was later learned that the operator had ignored the potential problems arising from the drilling, and that the wells had not been properly cemented, resulting in the leakage of formation fluids. Subsequent studies verified that the continuity of the extraction activity caused increases in the concentrations of methane and other pollutants at the regional level.
  • In 2009, in Dimock, Pennsylvania, the migration of methane from thousands of feet deep from the production formation resulted in contamination of an aquifer and at least one explosion on the surface. Subsequently, the migration of methane caused the contamination of more than a dozen water sources in an area of ​​1,400 hectares.
  • In July 2009, in McNett Township, Pennsylvania, the Department of Environmental Protection (DEP) discovered a natural gas leak that contaminated two bodies of water, and affected numerous residential drinking water wells in the area.
  • In April 2009 drilling activities impacted at least seven drinking water sources in Foster Township, Pennsylvania; two were contaminated with methane, and five with iron and manganese above the maximum allowed. Following the investigation, the local DEP concluded that the contamination was the result of “26 recently drilled wells”, the casings of which were not properly cemented, or were subjected to excessive pressure.
  • Between March and May 2009, in Fremont County, Wyoming, the EPA conducted an investigation into allegations of bad odor and taste of water in residential wells, concluding that they were due to high levels of dangerous contaminants, including which included those used in a nearby hydraulic fracturing operation.
  • On June 3, 2010, a gas well explosion in Clearfield County, Pennsylvania, sprayed the air with natural gas and liquid waste for 16 hours, reaching a height of 23 meters. For it, “untrained personnel” and “inappropriate control procedures” were blamed, for which the well operators were fined US $ 400,000, and all well operations were ordered to be suspended for 40 days.


Once the drilling and hydraulic fracturing process is completed, the extraction of the hydrocarbon begins. In general, production volumes decrease rapidly, reducing to around one fifth between the first and fifth year of operation. For this reason, it is common for operators to decide to re-fracture the well several times to extend its economic life -which involves re-injecting large amounts of water and chemicals into it.

Surface contamination

The risks and impacts on the surface are not less than those described for the underground level. We must bear in mind that drilling a six-well platform involves:

  • 830 m3 of soil removal, in wells drilled to a depth of 2,000 km and 1.2 km horizontal;
  • Transportation and storage of substances used in hydraulic fracturing, which would amount to between 1,000-3,500 m3 of chemicals.
  • Each platform can generate up to 23,000 m3 of liquid waste, including fluids used in drilling and those that migrate from the depths;
  • Basins for waste storage, whose average storage volume is around 2,900m3, so a 3m deep basin requires a surface area of ​​1000m2 (0.1 hectares). To this, temporary storage tanks must be added, taking into account the high rate of return of the fluids used for hydraulic fracturing.

The main threats on the surface in these processes involve:

  • Spills, overflows or leaks due to: limited storage capacity / human error / ingress of rainwater or floods / faulty construction of wells.
  • Spillage of concentrated fracturing fluids during transfer and mixing with water due to: piping failures / human error.
  • Spillage of fracture fluids once the fracture is concluded, during transfer for storage, due to: failure of the pipes / insufficient storage capacity / human errors.
  • Loss of already stored fluid, due to: ruptured tanks / overload due to human error or limited storage capacity / water ingress from storms or floods / improper liner construction.
  • Spillage of fluids that return to the surface during transfer from their storage place to tanker trucks for transport, due to: pipe failures / human error.

The Tyndall Center report argues that “since shale gas development requires the construction of multiple wells / well pads, the probability of an adverse event causing contamination is greatly increased. Thus, the chance of contamination incidents associated with further development [of unconventional gas] increases from 'possible' at the level of a well platform to 'probable' as the number of wells and platforms increases ”(Tyndall Center, 2011 : 68).

As in the case of groundwater, there have also been reports of contamination on the surface:

  • In September 2009, in Dimock, Pennsylvania, two liquid gel spills occurred on a well pad, contaminating a swamp and causing a severe fish kills. Both involved a lubricating gel used in the hydraulic fracturing process, and totaled 30,000 liters, being caused by failures in the pipes. In this same place, diesel fuel spills were also reported, causing contamination in a swamp and on land.
  • In September 2009 in Monongalia County, West Virginia, a massive fish kill occurred along the Pennsylvania border. More than 30 miles of the water course were impacted by a discharge from West Virginia. DEP had received numerous complaints from residents, who suspected the companies were dumping drilling waste illegally.
  • In December 2006, the Pennsylvania DEP ordered two companies to discontinue their work due to repeated violations of environmental regulations, among which was the illegal discharge of water saturated with salt on land.

The investigation highlights that given the number of cases reported in recent years, and the virtual impossibility of monitoring and controlling each of the processes involved in the exploitation of unconventional gas, the EPA announced, in January 2010, the creation a telephone line for inquiries and complaints –called “Eyes on drilling” - for citizens to report the existence of “suspicious” activities related to natural gas exploitation.

Other impacts

Finally, apart from the contamination that could occur for the aforementioned reasons, impacts derived from:

  • Noise pollution: The set of activities that must be developed prior to the production stage entails between 500 and 1,500 days of activity with strong impact, being the drilling of wells the most important. The estimates made show that each well platform requires between 8 and 12 months of drilling 24 hours a day.
  • Impacts on the landscape: Regarding visual impacts, each well platform implies a deployment in territory of between 1.5-2 hectares, which includes the construction of access routes, and the installation of storage pools, tanks, drilling equipment, transport trucks, etc. The number of well platforms necessary to satisfy a minimum demand for gas multiplies the impacts and makes the incompatibility of these projects with the landscape more evident.
  • Increased traffic and damage to roads and highways: Each well platform requires between 4,300 and 6,600 trips by truck to transport machinery, supplies, etc. The damages have become so significant that the West Virginia Department of Transportation has decided to collect between US $ 6,000 and US $ 100,000 from operators in compensation.

As of today, the Neuquén basin is at the forefront in the initiation and development of this type of project. The highly uncritical euphoria with which they were announced, and the fact that they would be located in a region already severely affected by conventional hydrocarbon exploitation, herald a turbulent scenario in the near future.


1. By the way, the economist Diego Mansilla has commented that “in 'Loma de la Lata' […] the existence of structures with unconventional gas was known several years ago, so the announced 'discovery' denomination is erroneous since It would not be about […] unknown new reserves, but it was possible to pass the estimates of 'possible reserves' […] to proven reserves ”(Mansilla, 2010: s / n)



Promotional video of horizontal drilling and hydraulic fracturing techniques. Translation:

Shale gas extraction pollutes the water with methane. BBC World

Bibliography:, 4/18/2011: "Argentina in third place in the world in unconventional gas". Recovered from:…

La Mañana Neuquén, 3/5/2011: "Sapag offers the Neuquén basin to the Nation to substitute imports." Recovered from: http: //…

Mansilla, D. (2010). Lights and shadows of the gas discovery in Neuquén. South Development. Available at:…

Tyndall Center for Climate Research. (2011). Shale gas: a provisional assessment of climate change and environmental impacts. Available at:…

Video: The journey of natural gas (July 2022).


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