Lesson 20 - Hydrofracking
· How do you "frack"?
o Drilling horizontal wells in shale layers at depth § Go straight down then sideways o Inject high pressure fluids - shatter the rock creating tons of fractures. § 90% water § <1% toxic chemicals § 9% sand
· Other concerns of hydraulic fracturing
o Earthquakes (induced seismicity) associated with injection wells usually wastewater disposal wells from fracking projects where this seismic activity is. § According to the U.S. geological survey, hydraulic fracturing causes small earthquakes, but they are almost always too small to be a safety concern. In addition to natural gas, fracking fluids and formation waters are returned to the surface. These wastewaters are frequently disposed of by injection into deep wells. The injection of wastewater into the subsurface can cause earthquakes that are large enough to be felt and may cause damage. o Explosions may cause injury or contaminate environment (methane is highly flammable)
· What is natural gas?
o Formed by organic matter (marine organisms) trapped in sedimentary rocks (thermogenic transformation organisms aka plankton) or biogenic means farting of microbes aka producing methane while digesting food and respirating but the natural gas held in these shales we're going to frack is thermogenic o Flows like a liquid through pores in rocks
· The environmental impacts of fracking alone are acceptable if they took place away from communities but the richest shale gas deposits are indeed in populous areas with lots of private lands, homes, and drinking wells.
o If you were in the middle of nowhere with the fracking operations it would be less controversial.
· What is "fracking"?
o Industrial practice of injecting fluids into shale
· Fracking fluids - role of sand
to hold the cracks open so gas can escape, the increased permeability can keep open
Most of the riggs are usually spaced on 40 acre plots, this is an aerial view of the Jonah Field in the rock mountains. Everywhere there is a clear pad with buildings is apart of the hydrofracking. Issues with this are the fact that they're big productions., the gas is spread out in the subsurface so you have to spread out your drill rigs in that area.
The farther you can horizontally drill from a single well the more area you can extract from which means fewer wells. The outlook for decreasing the aerial foot print is getting better in the last decade
o Natural gas is one of the lightest ('thermally mature forms at higher temperatures) forms of petrochemicals (oil)
o Burning produces less CO2 per energy unit created than any other fossil fuels
· Community changes - other reasons many communities are polarized on fracking
o Cons: § Noise and light pollution § Stress and mental health (environmental concerns, economic change, conflict) § Impacts on health services (visits to emergency room, disaster/spill response, new disease concerns) § Increased housing costs/demand o Pros § Benefits are improved economy § Depend on who you ask: Population/community change (workers)
· Concern #2 ground water and health
o Misconception: you're pumping these fluids directly into the shales which is not true, they're very deep. In order to go deeper to where we inject them we have to go through these aquifers. o Potential issues: § Fracking fluids are injected hundreds to thousands of meters below groundwater aquifers. But, the wells do need to be drilled through these aquifers... there is potential for leaks through compromised well casings (foot thick cement casing). o Effects: § If mismanaged, methane or fracking chemicals may leak into private drinking water wells. Most concerned about but least documented.
· Natural Gas in the US
o Most of our Natural Gas in the US is shale gas (considered an unconventional fuel) o How these shales are in the subsurface of the earth:
o Earthquakes happening far from plate boundaries, which is weird.
o Most of these are induced seismicity from fracking oil or natural gas wells. o Look at the abundance in the US that occur after the mid 2000s which is when fracking technologies widely came into use. The growth of fracking in natural gas and oil production and abundance in earthquakes are correlated.
· Challenges of discussing hydrofracking
o Polarized: § Big business v. small communities § Environment v. economy § Fracking v no fracking o Distribution of costs and benefits o Multidisciplinary - different "frames" o Uncertainty and conflicting information o "People listen to who agree with them"
· Concern #3 Air quality and health
o Potential issues § Diesel engines (trucks, compressors, etc.) create air pollution particulates, ozone precursors § Fugitive emissions from wells (i.e. what if an accident causes methane to escape wells) · Some natural gas leaks into the atmosphere from oil and natural gas wells, storage tanks, pipelines, and processing plants. These leaks were the source of about 32% of total U.S. methane emissions and about 4% of total U.S. greenhouse gas emissions in 2015. The oil and natural gas industry takes steps to prevent natural gas leaks. o Effects § Pollutants could be inhaled by workers, neighbors, regional communities § The other adverse affect is that when we leak methane we contribute to climate change because methane is a very potent greenhouse gas.
· Concern #1 Surface water issues
o Potential issues § Fracking chemicals/flowback water may be spilled at surface - the effect is the first point § Overuse of water resources - the effect is the second point o Effects § If mismanaged, hydraulic fracturing fluid - which may contain potentially Hazardous chemicals - could be released through spills or leads contaminating surrounding areas · Exposure: fish/game consumption, contact recreation, farm animals § The fracturing of wells requires large amounts of water. In some areas of the country, significant use of water for fracking may affect aquatic habitats and the availability of water for other uses.
· Hydraulic Fracturing (aka "fracking") or hydrofracking mean the same thing
o Primarily used to extract natural gas or oil from tight shale formations o Involves horizontal drilling and insertion of fluid into subsurface which fractures rock, increasing permeability which allows hydrocarbons in that rock to be able to more easily flow out more easily so we can recover them.
· Induced seismicity - another impact of fracking
o Pumping fluids twice in fracking, once to crack the shale, (below magnitude three and very low chance) and one when we dispose of wastewater which is where the induced seismicity is more of a problem (what causes more concerning induced seismicity usually still small but some have been magnitude 6)
o Wastewater is produced at oil wells, not just fracking wells
o Seismicity can occur significant distances from the injection wells and at greater depths o Most of these earthquakes are in the magnitude 3-4 range - large enough to have been felt by many people - yet small enough to rarely cause damage o Damage has been caused by some of the larger events, including the M5.8 Pawnee and M5.0 Cushing Oklahoma earthquakes that occurred in 2016.
· What counts as evidence? Listed in order of increasing reliability.
o Stories/reports from affected citizens, health care provides, or organizations o Newspaper articles o Evidence of past impact? o Predictions of future impacts? o Government agency reports o Peer-reviewed publications
· Role of Natural Gas in electricity generation in the US
o The natural gas is the most important fossil fuel/energy source for electricity generation then coal and nuclear, and a combination of renewable resources
· Marcellus shale one of the largest shale deposit, located · Fluids are injected along the horizontal well, the high pressure of fluid induces fracturing of shale layer.
o The role of the sand is after the fractures open, the sand flows into the fractures get stuck which keeps them open wide, then gas can leak into fractures and flow up the well.
· Hydraulic fracturing aka fracking
o Used to recover oil and gas that did not escape from shale layers in which they formed (oil shales) o Been used since 1950's
· How do we use natural gas?
o We use it in the use for a number of reasons the most important is electricity generation. o Heating internal spaces in commercial and residential spaces o Industrial purposes aka factories, energy sources for large industrial operations
· Fracking involves a bunch
of trucks, drill rigs, well.
o Water - high volume - additional issue - the large amount of water used
§ 500,000 to 10 million gallons of water may be used to frack ONE WELL § Strain on drinking and agricultural water resources § Much of that water flows back up the well and must be disposed of, flows back out as we recover the gas and is now contaminated with the chemical additives of the fracking fluid, nasty stuff it comes in contact with in the subsurface and salty stuff (deep groundwater which has saline)
Controversy includes many issues:
§ All activities at well site o Other physical processes associated with shale gas extraction § Trucks, compressor stations, pipelines o Changes in communities and economies resulting from shale gas development Traffic, noise, pollution, health effects, water resources, other
Fracking nor Hydraulic fracturing not inherently more risky or dangerous than other methods of oil/gas interaction
§ Biggest difference - these operations cover a lot more area - gas is more spread out in the formation in the subsurface § Take a LOT more drilling and pumping and installing pipelines in more places · More likely to be in someone's backyard, affects more communities · The more drilling there is, the more chances there are for mistakes
· What is a health effect?
§ Difficult to quantify o Health impacts/symptoms directly caused by hydrofracking o Changes in incidence of disease associated with increased hydrofracking o Changes in environmental quality or animal health that could impact humans o Well-being/quality of life (stress, conflict, wealth, sense of belonging/community) Health effects can be difficult to quantify but these issues are a concern of people who live near fracking operations
o Natural gas is the best of fossil fuels because burning it creates the least CO2 of fossil fuels.
§ Fracking for natural gas is considered unconventional
o Chemical additives
§ Kind of a mystery to consumers § Proprietary by the companies doing the fracking therefore are not available to the public which lends to the fear surrounding fracking. § It is known the chemicals are toxic but the most important chemical in these mixtures:
But more often than not fracking is happening around long-established communities. The parts of US: north east, Texas, some parts of the west have the most fracking but the north east is home to largest deposits of shale gas so when you combine the impacts of fracking and the mystery around fracking with large communities we create a lot controversy.
§ More often than not fracking is happening around communities, north east, Texas, and some parts of the west is where it usually happens
o The organic material in the gas rich shale is thermogenicly transformed into natural gas and some of it can leave and move up into permeable reservoir rock a trap where it is considered a conventional deposit of natural gas.
§ Or that gas can be stuck in those tighter rocks § Tight sand gas is just suck in the sandstone layer and has lower porosity and permeability. § Not shown in the image but a lot of natural gas may be left behind in the shale it originally formed in.
o Pumping wastewater into deeper wells is the primary cause of earthquakes
§ Some earthquakes are caused by the fracking itself, but these are typically smaller and much fewer (1-2%) § Wastewater disposal wells typically operate for longer durations and inject much more fluid than hydraulic fracturing, making them more likely to induce earthquakes
o Shows natural gas production by resource type
§ The very thin line is Alaska but in yellow natural gas that comes from offshore deposits stored in conventional traps located in deep water environment, black is coal bed methane, red is other lower 48 onshore, rust color is tight gas, and green is shale gas (often associated with tight oil plays) and tight oil plays. Shale gas is becoming the most important source of natural gas in our country. o ~30% predicted increase in natural gas production between 2015 and 2040 o Most of the increase is in the production of shale gas
o Fractures allow fracking fluids plus salty brines (saline ground waters that exist at great depth in the earth) from the rocks flow back out of the wells
§ These fluids need to be disposed of the disposal - typically in other deep wells of fracking fluid can cause seismicity. § Causes earthquakes
o A broad technique, but can be applied to extract oil from tight oil shale formations and also most widely used to extract natural gas or shale gas from deep shales
§ This technique also used to extract oil from tightly held oil reservoirs like those tight oil shales. Horizontal drill rig
o "Unconventional" natural gas remains trapped in pores in tighter rocks (shale)
§ What we frack for, gas is trapped in a low permeability rock (shale)
o "Conventional" natural gas collects in porous rock (sandstone) domes make get caught in a trap (anticlinal, fault, stratigraphic)
§ When natural gas is held, usually with oil, in a conventional trap in subsurface .. traps above
Probably includes chemicals that
· Help gas (methane) bubbles merge so they can flow more easily o Analogy we take Gas Relief pills (chemicals simethicone) the presence of the chemical and methane combine into bubbles so you can burp them out easy. This is a similar process when we look at fracking · Prevent bacteria from "eating" the gas before we can use it o Some present at the top but when we dig down we find more bacteria that actually break down methane, this chemical additives keep that from happening.
