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Shale Gas and Hydro-fracking (Fracking)

Shale gas is defined as natural gas from shale formations.  The shale acts as both the source and the reservoir for the natural gas.  Older shale gas wells were vertical while more recent wells are primarily horizontal and need artificial stimulation, like hydraulic fracturing (fracking), to produce.  Only shale formations with certain characteristics will produce gas.  The most significant trend in US natural gas production is the rapid rise in production from shale formations.  In large measure this is attributable to significant advances in the use of horizontal drilling and well stimulation technologies and refinement in the cost-effectiveness of these technologies.  Hydraulic fracturing is the most significant of these.

Fracking wellhead

Some analysts expect that shale gas will greatly expand worldwide energy supply.  Increased shale gas production in the US and Canada could help prevent Russia and Persian Gulf countries from dictating higher prices for the gas it exports to European countries.  However, potential leakages of methane gas from shale gas wells could offset the carbon dioxide reductions and climate benefit of switching from coal to natural gas, as methane is 21 times more powerful as a greenhouse gas than carbon dioxide, ton-for-ton.

Although shale gas has been produced for more than 100 years in the Appalachian Basin and the Illinois Basin of the United States, the wells were often economically marginal.  Higher natural gas prices in recent years and advances in hydraulic fracturing and horizontal completions have made shale gas wells more profitable.

The natural gas boom in the US due to hydraulic fracturing (fracking) has provided the country with a cleaner burning, inexpensive fuel source that has lowered energy bills for industrial facilities and homeowners alike.  The fracking process is still a hot topic of controversy wherever it is used to extract fuel.  Environmentalists claim it will ruin watersheds and leave scars on the earth, and other concerns range from flammable tap water to carcinogenic soil.  Here are just three things fracking won’t do.

Shale has low matrix permeability, so gas production in commercial quantities requires fractures to provide permeability.  Shale gas has been produced for years from shales with natural fractures; the shale gas boom in recent years has been due to modern technology in creating extensive artificial fractures around well bores.  Horizontal drilling is often used with shale gas wells.

Isolated incidents of pollution to freshwater wells have been caused when drilling is done too close to the surface, and natural gas companies have settled several cases where damage is attributed to the gas wells.  The point is, however, that the horror story of flammable water is extremely uncommon.  For one thing, the drilling components used to trap the natural gas are encased in steel and cement to prevent it from escaping.  If the casing is done properly, it is nearly impossible for methane gas to escape.  Also, fracking is done so far underground, that escaped methane would have to travel through solid rock in order to contaminate aquifers.  There are reports that this has happened due to problems like improperly cemented boreholes.  16 families in Pennsylvania were affected by such an incident.  As a result, the drilling company was fined over $1 million.  Problems like this are rare, and can be completely avoided by constructing and sealing equipment properly.

There are several claims around the world, that fracking activity has spurred a number of low-registering seismic disturbances.  A 2013 study by Durham University found fracking to be “not significant” in causing earthquake activity.  The study explains that seismic disturbances caused by hydraulic fracturing are minimal.  So small, in fact, that they would only be detectable by the sensitive instruments used by geoscientists.

It would be nearly impossible for hydraulic fracturing to cause any major earthquakes unless drilling equipment were to come into contact with a major fault line and somehow because the fault to release any built up energy it has stored.  The study concluded, “The fact is that court case after court case and study after study have shown plainly that fears over earth tremors have no basis in fracking facts”.

Fears over pollution and contamination of drinking water and the environment from fracking fluid seem to stem from a lack of information about what this rock-shattering mixture actually is.  The secret to fracking fluid is water and sand.  Those two components make up about 98% of the fluid mix.  The remaining 2% is composed of ingredients that are familiar to many of us, such as citric acid, guar gum (a common food additive, used to suspend the sand in the fluid), and even common table salt.  Certainly not all of these chemicals are harmless to the environment or to drinking water.  But, the fracking industry has a habit of recovering most of its fluid and recycling it.  This does not prevent every drop of fluid from being spilled, but it certainly means that most of the material is recovered.  This saves the company doing the drilling money as well as improving its environmental impact.

Like any method of recovering fossil fuels, hydraulic fracturing does do damage to the environment.  But, even accounting for methane leakage during extraction, the total carbon cost of natural gas is less than that of coal or oil.  The transition to natural gas for power generation in many places has led to a drop in carbon emissions for the United States.  Since the world is not yet ready for 100% renewable energy, natural gas could be a suitable energy source to “bridge the gap” in the transition to truly renewable fuel.

Shales that host economic quantities of gas have a number of common properties.  They are rich in organic material (up to 25%), and are usually mature petroleum source rocks in the thermogenic gas window, where high heat and pressure have converted petroleum to natural gas.  They are sufficiently brittle and rigid enough to maintain open fractures.  Some of the gas produced is held in natural fractures, some in pore spaces, and some is adsorbed onto the organic material.  The gas in the fractures is produced immediately; the gas adsorbed onto organic material is released as the formation pressure is drawn down by the well.

Chemicals are added to the water to facilitate the underground fracturing process that releases natural gas.  The resulting volume of contaminated water is generally kept in above-ground ponds to await removal by tanker or injected back into the earth.

As an example, Canada is estimated to hold vast reserves of shale, some of which would require fracking in order to be developed.  The reserves are estimated to have a market value of up to $4.6 trillion.  In Quebec alone, shale gas deposits are worth between $70 billion and $140 billion at current natural gas prices.

In support of arguing against any ban on fracking, the journal Science recently said that worldwide, “more than one million hydraulic fracturing treatments have been conducted, with perhaps only one documented case of direct groundwater pollution resulting from injection of hydraulic fracturing chemicals used for shale gas extraction.”  The report acknowledges that “there is no question that the technology poses some risk to air quality, water quality, and ecosystem health.  It also poses a risk of increasing greenhouse gas emissions”.  However, it asserts that these factors can be mitigated sufficiently with current technologies as to not pose a risk that is significant enough to justify a blanket ban on the practice.

A ban on fracking would prevent companies, governments and the public from assessing the true risks as it would prevent experimentation and refining of techniques.  In addition the report suggests that other measures can be taken to improve the fracking regulatory process including increased insurance, implementing tracking technologies to monitor waste disposal and environmental damages, and development of independent organisations to monitor activities and recommend improvements.

Paul A. Lawrence MBA, BSc, CEng, FIChemE, FIGEM, FCMI

May 2017

 

 

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