Fracking the Country
Hydraulic fracturing of rock is a major new source of natural gas and oil for the US and will change life in this country.
Delivered by Rich Winsor, May 21, 2013
Energy is critical to economic development. This is because the cost of energy is a major determinant of the cost of everything we purchase and especially for important items like food, housing, and transportation. Some economists have observed that energy cost generally determines whether an economy prospers or performs poorly.
With energy being so important, I was originally going to talk about nuclear power, because that appeared to be a major energy source for the future. However, I changed topics because now natural gas and oil from "fracking" shale has become much more important to the energy future of the country.
First we need to understand what "fracking" is and how it works, and then we need to discuss the advantages and disadvantages of using it. Please note that most of this material is quoted from Wikipedia, which I find is often a good source of information with relatively little bias.
Hydraulic fracturing is the propagation of fractures in a rock layer, by a pressurized fluid. Some hydraulic fractures form naturally—certain veins or dikes are examples—and can create conduits along which gas and petroleum from source rocks may migrate to reservoir rocks. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas (including shale gas, tight gas, and coal seam gas), or other substances for extraction. This type of fracturing creates fractures from a wellbore drilled into reservoir rock formations.
The first use of hydraulic fracturing was in 1947, but the modern fracking technique, called horizontal slickwater fracking, that made the extraction of shale gas economical was first used in 1998 in the Barnett Shale in Texas. The energy from the injection of a highly pressurized fracking fluid creates new channels in the rock, which can increase the extraction rates and ultimate recovery of hydrocarbons.
Proponents of fracking point to the economic benefits from vast amounts of formerly inaccessible hydrocarbons that the process can extract. Opponents point to potential environmental impacts, including contamination of ground water, risks to air quality, the migration of gases and hydraulic fracturing chemicals to the surface, surface contamination from spills and flowback and the health effects of these. For these reasons hydraulic fracturing has come under scrutiny internationally, with some countries suspending or even banning it. Let's discuss fracking in greater detail.
Fracturing as a method to stimulate wells dates back to the 1860s, and using acid to open fractures was introduced in the 1930s. The first hydraulic fracturing experiment was conducted in 1947 in southwestern Kansas, and in 1949 Halliburton performed the first two commercial hydraulic fracturing treatments in Oklahoma and Texas. Since then, hydraulic fracturing has been used to stimulate approximately a million oil and gas wells.
The technique of hydraulic fracturing is used to increase or restore the rate at which fluids, such as petroleum, water, or natural gas can be produced from subterranean natural reservoirs. Reservoirs are typically porous sandstones, limestones, or dolomite rocks, but also include "unconventional reservoirs" such as shale rock or coal beds. Hydraulic fracturing enables the production of natural gas and oil from rock formations deep below the earth's surface (generally 5,000–20,000 feet). At such depth, there may not be sufficient permeability or reservoir pressure to allow natural gas and oil to flow from the rock into the wellbore at economic rates. Fractures provide a conductive path connecting a larger volume of the reservoir to the well. However, the yield for a typical shale gas well generally falls off sharply after the first year or two.
A hydraulic fracture is formed by pumping the fracturing fluid into the wellbore at a rate sufficient to increase pressure downhole to exceed that of the fracture gradient of the rock. The rock cracks and the fracture fluid continues further into the rock, extending the crack still further, and so on. Operators typically try to maintain "fracture width", or slow its decline, following treatment by introducing into the injected fluid a proppant – a material such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped and the pressure of the fluid is reduced. During the process, fracturing fluid leakoff, i.e. loss of fracturing fluid from the fracture channel into the surrounding permeable rock occurs.
Horizontal drilling involves wellbores where the terminal drill hole is completed as a "lateral" that extends parallel with the rock layer containing the substance to be extracted. Laterals extend 1,500 to 5,000 feet in the Barnett Shale basin in Texas and up to 10,000 feet in the Bakken formation in North Dakota. The location of one or more fractures along the length of the borehole is strictly controlled by various methods that create or seal off holes in the side of the wellbore. Typically, hydraulic fracturing is performed in cased wellbores and the zones to be fractured are accessed by perforating the casing at those locations.
The two main purposes of fracturing fluid is to extend fractures and to carry proppant into the formation. The purpose of proppant is to stay there without damaging the formation or production of the well. The fluid injected into the rock is typically a slurry of water, proppants, and chemical additives. Additionally, gels, foams, and compressed gases, including nitrogen, carbon dioxide and air can be injected. Typically, the fracturing fluid is 98–99.5% is water and sand with the chemicals accounting to about 0.5%. Hydraulic fracturing uses 1 to 5 million gallons of fluid per well, and additional fluid is used when wells are refractured; this may be done several times.:
A proppant is a material that will keep an induced hydraulic fracture open, during or following a fracturing treatment. Types of proppant include silica sand, resin-coated sand, and man-made ceramics. These vary depending on the type of permeability or grain strength needed.
The friction reducer is usually a polymer, the purpose of which is to reduce pressure loss due to friction, thus allowing the pumps to pump at a higher rate without having greater pressure on the surface. The main way most friction reducers work is by changing turbulent flow to laminar flow, also many of the friction reducers are polyacrilamide which are good suspension agents ensuring the proppant does not fall out.
Chemical additives are applied to tailor the injected material to the specific geological situation, protect the well, and improve its operation, varying slightly based on the type of well. The composition of injected fluid is sometimes changed as the fracturing job proceeds. Often, acid is initially used to scour the perforations and clean up the near-wellbore area. Afterward, high-pressure fracture fluid is injected into the wellbore, with the pressure above the fracture gradient of the rock. This fracture fluid contains water-soluble gelling agents which increase viscosity and efficiently deliver the proppant into the formation. As the fracturing process proceeds, viscosity reducing agents such as oxidizers and enzyme breakers are sometimes then added to the fracturing fluid to deactivate the gelling agents and encourage flowback. At the end of the job the well is commonly flushed with water (sometimes blended with a friction reducing chemical) under pressure. Injected fluid is to some degree recovered and is managed by several methods, such as underground injection control, treatment and discharge, recycling, or temporary storage in pits or containers. Over the life of a typical gas well, up to 100,000 gallons of chemical additives may be used.
Since the early 2000s, advances in technology has made drilling horizontal wellbores much more economical. Horizontal wellbores allow for far greater exposure to a formation than a conventional vertical wellbore. This is particularly useful in shale formations which do not have sufficient permeability to produce economically with a vertical well. The wellbore is divided into sections that are fractured sequentially. There be more than 30 stages in the horizontal section of a single well. This multi-stage fracturing technique has facilitated shale gas and light tight oil production development in the United States and may make us energy independent. Recently, China was estimated to have twice the unconventional oil and gas resources of the United States.
Hydraulic fracturing has raised environmental concerns and is challenging the adequacy of existing regulatory regimes. These concerns have included ground water contamination, risks to air quality, migration of gases and hydraulic fracturing chemicals to the surface, mishandling of waste, and the health effects of all these.
A University of Texas study led by Charles Groat described the environmental impact of each part of the hydraulic fracturing process, which included:
- Drill pad construction and operation
- Construction, integrity, and performance of the wellbores
- Injection of the fluid once it is underground (which proponents consider the actual "fracking")
- Flowback of the fluid back towards the surface
- Blowouts, often unreported, which spew hydraulic fracturing fluid and other byproducts across surrounding area
- Integrity of other pipelines involved
- Disposal of the flowback, including waste water and other waste products
Several organizations, researchers, and media outlets have reported difficulty in conducting and reporting the results of studies on hydraulic fracturing due to industry and governmental pressure, and expressed concern over possible censoring of environmental reports. Researchers have recommended requiring disclosure of all hydraulic fracturing fluids, testing animals raised near fracturing sites, and closer monitoring of environmental samples. After court cases concerning contamination from hydraulic fracturing are settled, the documents are sealed. The American Petroleum Institute denies that this practice has hidden problems with gas drilling, while others believe it has and could lead to unnecessary risks to public safety and health.
One New York Times report claimed that the results of a 2004 United States Environmental Protection Agency study were censored due to political pressure. An early draft of the study had discussed the possibility of environmental threats due to fracking, but the final report omitted this. The study's scope had been narrowed so that it only focused on the injection of fracking fluids, while omitting other aspects of the process. The 2012 EPA Hydraulic Fracturing Draft Plan was also narrowed thusly.
The air emissions from hydraulic fracking are related to methane leaks originating from wells, and emissions from the diesel or natural gas powered equipment such as compressors, drilling rigs, pumps, etc. In some areas, elevated air levels of harmful substances have coincided with elevated reports of health problems among the local populations. In Dish, Texas, elevated substance levels were detected and traced to fracking compressor stations, and people living near shale gas drilling sites complained of health problems, though a causal relationship to fracking was not established.
The large volumes of water required have raised concerns about fracking in arid areas, During periods of low stream flow it may affect water supplies for municipalities and industries such as power generation, as well as recreation and aquatic life. It may also require water overland piping from distant sources. An average US well requires 3 to 8 million gallons of water.
There are concerns about possible contamination by hydraulic fracturing fluid both as it is injected under high pressure into the ground and as it returns to the surface. To mitigate the impact of hydraulic fracturing to groundwater, the well and ideally the shale formation itself should remain hydraulically isolated from other geological formations, especially freshwater aquifers. While some of the chemicals used in hydraulic fracturing are common and generally harmless, some are known carcinogens or toxic. The most common chemical used for hydraulic fracturing in the United States in 2005–2009 was methanol. An investigative report on the chemicals used in hydraulic fracturing states that out of 2,500 hydraulic fracturing products, "more than 650 of these products contained chemicals that are known or possible human carcinogens, regulated under the Safe Drinking Water Act, or listed as hazardous air pollutants". The report also shows that between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their required material safety data sheet.
Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it more difficult to prove that hydraulic fracturing is contaminating the environment with these substances.
Another 2011 study identified 632 chemicals used in natural gas operations. Only 353 of these are well-described in the scientific literature. The study recommended full disclosure of all products used, along with extensive air and water monitoring near natural gas operations; it also recommended that fracking's exemption from regulation under the US Safe Drinking Water Act be rescinded.
As the fracturing fluid flows back through the well, it consists of spent fluids and may contain dissolved constituents such as minerals and brine waters. These fluids, commonly known as flowback or wastewater, are managed by underground injection, wastewater treatment and discharge, or recycling to fracture future wells. Treatment of produced waters may be feasible through either self-contained systems at well sites or fields or through municipal waste water treatment plants or commercial treatment facilities. However, the quantity of waste water needing treatment and the improper configuration of sewage plants have become an issue in some regions of the United States. Much of the wastewater from hydraulic fracturing operations is processed by public sewage treatment plants, which are not equipped to remove radioactive material and are not required to test for it.
Groundwater methane contamination is also a concern as it has adverse impact on water quality and in extreme cases may lead to potential explosion. However, methane contamination is not always caused by fracking. Drilling for ordinary drinking water wells can also cause methane release. Several studies have determined that methane migration into freshwater zones has occurred some areas, most likely as a result of substandard well completion practices.
Hydraulic fracturing fluid might release heavy metals and radioactive materials from the deposit which may reflow to the surface by the flowback. Concerns have been expressed that radioactive tracers may return to the surface with flowback and during blow outs. Recycling the wastewater has been proposed as a solution but has its limitations. The EPA has asked the Pennsylvania Department of Environmental Protection to require community water systems in certain locations, and centralized wastewater treatment facilities to conduct testing for radionuclides.
Hydraulic fracturing causes induced seismicity called microseismic events or microearthquakes. The magnitude of these events is usually too small to be detected at the surface. The injection of waste water from gas operations, including from hydraulic fracturing, into saltwater disposal wells may cause bigger low-magnitude tremors.
The United States Geological Survey has reported earthquakes induced by human measures, including hydraulic fracturing and the waste disposal wells, in several locations. According to the USGS only a small fraction of roughly 40,000 waste fluid disposal wells for oil and gas operations have induced earthquakes that are large enough to be of concern to the public. Although the magnitudes of these quakes has been small, the USGS says that there is no guarantee that larger quakes will not occur. In addition, the frequency of the quakes has been increasing. There are also concerns that quakes may damage underground gas, oil, and water lines and wells that were not designed to withstand earthquakes.
Several earthquakes occurring throughout 2011, including a 4.0 magnitude quake on New Year's Eve that hit Youngstown, Ohio, are likely linked to a disposal of hydraulic fracturing wastewater, according to seismologists at Columbia University. A similar series of small earthquakes occurred in 2012 in Texas. Earthquakes are not common occurrences in either area.
To control the hydraulic fracturing industry, some governments are developing legislation and some municipalities are developing local zoning limitations. In 2011, France became the first nation to ban hydraulic fracturing. Other countries have placed a temporary moratorium on the practice. The US has the longest history with hydraulic fracturing, so its approaches to hydraulic fracturing may be modeled by other countries.
In the public argument over "fracking", there is some divergence in the use of the word "fracking". In one study the term "fracking" was narrowly defined as only referring to the injection of fluid under pressure to create pathways. The study's definition excluded the impact of equipment failure, the nature of the fluids themselves, the preparations prior to injection, and procedures and events following the injection. Others, including the U.S. Environmental Protection Agency, hold "fracking" to mean the entire process of resource extraction, specifically of gas in shale, starting with building the well pads through recovering the gas, and dealing with the wastewater. This differing usage allows newspapers such as the Vancouver Sun to state that fracking has never contaminated groundwater, while The New York Times reports that it likely has.
In summary, hydraulic fracturing is a major economics and energy issue for the US and may provide energy independence in the next 10 - 20 years. The question is "can we obtain this energy without excessive damage to our water, air, and climate?"