We weren t planning to talk about it, but since you asked... CEE With special thanks to Dr. Brian Rahm of the NY State Water Resources Institute

Transcription

1 We weren t planning to talk about it, but since you asked... CEE 3510 With special thanks to Dr. Brian Rahm of the NY State Water Resources Institute

2 Hydraulic fracturing ( fracking ) is used to enhance the permeability of subsurface rock formations (typically shale) containing natural gas. Fracking allows gas to flow more readily to the wellbore. The pumping of large volumes of a low-viscosity, water/sand slurry into the shale induces new fractures and augments existing fractures in the shale. 2 to 7 million gallons of water can be used per well Pressures used are 5,000 to 9,000 psi but can reach up to 15,000 psi. Hydraulic fracturing treatments are tailored to the specific characteristics of the target shale, including: thickness, compressibility, and rigidity.

3 Shale is a sedimentary rock that is mainly composed of clay-sized particles. Shales are often organic-rich and the organic content is thought to be the source for the gas hydrocarbons. The continental 48 states have a wide distribution of shales with a high organic content.

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5 Natural gas is colorless/odorless gas composed of flammable hydrocarbons (butane, ethane, propane) In the past it was not widely utilized as a fuel because of cost considerations. New Technology-horizontal drilling and hydraulic fracturing have made production of natural gas reserves economically feasible.

6 A vertical well can access the gas in a shale cylinder of 1,300 feet in diameter and about 50 feet high. A horizontal well can cover more shale surface than vertical well 4,000 times greater volume. This allows less wells to be drilled and therefore less cost.

7 Natural gas supplies about 22 % of the nation s energy. Shale gas comprises about 15% of natural gas produced in the U.S. Research indicates that US still has 1744 tcf (trillion cubic feet) of recoverable natural gas. Out of this 1744 tcf, 211 tcf are proven reserves that are economically recoverable The proven reserves can supply enough energy to heat 3.06 billion homes, generate 2.04 trillion kilowatt-hours of electricity, or fuel 2.53 billion natural gas-powered vehicles for one year.

8 Utilization of natural gas reduces carbon emissions vs. oil and coal. Development of natural gas reserves is considered by some to be a transition to a more environment-friendly alternative energy.

9 Water: 90.6% Proppant: 8.96% Other: 0.44% Fracture fluid composition by weight

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11 Many fracturing fluids contain chemicals that can be toxic to humans and wildlife, and chemicals that are known to cause cancer. These include potentially toxic substances such as diesel fuel, which contains benzene, ethylbenzene, toluene, xylene, and naphthalene; polycyclic aromatic hydrocarbons; methanol; formaldehyde; ethylene glycol; glycol ethers; hydrochloric acid; and sodium hydroxide.

12 Residents near fracking have complained about truck traffic, air pollution and water pollution. EPA is currently focusing on the toxic fumes (such as radon gas) released from gas production in response to an environmental group s lawsuit in The possibility of contamination of drinking water is another major concern. But, the EPA was prohibited from regulating fracking under the Safe Drinking Water act by the Bush administration in The cumulative effect of gas drilling in residential areas is unknown. It is difficult to effectively monitor multiple wells. Regulation of fracking varies from state to state.

13 The used fluid is saline, high in dissolved solids, and contains a mix of constituents that are of environmental concern. Some example components: (avg. conc.) {EPA std. for drinking water} Cl - (56,900 mg/l) {EPA 2 o : 250 mg/l}, also Br - (616 mg/l) TDS (93,200) {EPA 2 o : 500 mg/l} As (0.11 mg/l) {EPA 1 o : 0.05 mg/l} Ba (660 mg/l) {EPA 1 o : 2.0 mg/l} Benzene (480 μg/l) {EPA 1 o : μg/l} BOD (560 mg/l) Cd (.032 mg/l) {EPA 1 o : mg/l} Sr (820 mg/l) {EPA 1 o : 50 pci/l for beta emitters} Radon in the wastewater is also high. A geological survey report found millions of barrels of wastewater had radon 3,609 times the limit for drinking water, and 300 times more than the level allowed for nuclear plant discharge.

14 Monitoring: Waste Water Disposal Where does the wastewater go? All recent flowback and produced water for all Marcellus wells in PA Disposal method of waste fluids tracked by PA DEP (July Dec 2010) Based on information found at eporting.state.pa.us/publi creports/modules/welco me/welcome.aspx INDUSTRIAL TREATMENT PLANT 70% REUSE 19% INJECTION WELL 6% Public Wastewater treatment plant "SEE 3% COMMENTS" 2%

15 Wastewater Treatability Typical concentration in NY groundwater* (mg/l) Typical concentration in Marcellus flowback** (mg/l) POTW dilution based on 1% daily flow rule (mg/l) Treatment options*** Arsenic Barium Strontium Dilution Sulfide precipitation Ferric hydroxide precip. Distillation Sulfate precipitation Distillation Sulfate precipitation Distillation Chloride 30 60, Reverse osmosis Distillation * Based on USGS data from NY basins: Susquehanna; Delaware; Chemung; Mohawk ** Based on data in the NYSDEC dsgeis; Osborn & McIntosh (2010); Tamblin (2010) ***Based on Metcalf & Eddy; Keister (2010)

16 Treatment Capacity via POTWs Assumptions 100 Wells drilled per year 4.5 Million gallons water used per well 0.15 Fraction recovered as flowback 93,200 (mg/l) TDS in typical flowback (NYSDEC) 8 Millions gallons per day through Ithaca POTW 270 (mg/l) TDS in typical wastewater (Metcalf & Eddy) Regulatory Constraints (new PA regs) 500 (mg/l) TDS effluent discharge limit 0.01 Fraction of POTW daily flow allowed as flowback 9.3 Ithaca POTWs needed to dilute TDS from 100 wells

17 Methane is a powerful greenhouse gas. Even small leakages and emissions can create a large greenhouse gas footprint for shale gas. Based on current available data on emissions of methane from shale-gas development, the greenhouse gas footprint of shale gas is estimated by some to be worse than that of conventional natural gas, far worse than that of oil, and possibly worse than that of coal.

18 A study by Duke University researchers found high levels of leaked methane in well water collected near shale-gas drilling and hydrofracking sites. The scientists collected and analyzed water samples from 68 private groundwater wells across five counties in northeastern Pennsylvania and New York. The team s study detected measurable amounts of methane in 85% of the collected samples, and levels were 17 x higher on average in wells located within a kilometer of active hydrofracking sites.

19 Researchers at the Univ. of Texas, Austin found methane emissions to be 0.42% of a well site s gross natural gas production. That figure is lower than the EPA s most recent estimate of 0.47% and far below the National Oceanic & Atmospheric Administration s estimate of 6-12%. The study results have been challenged because only 190 sites were examined and industry controlled which sites were measured. *Source: Chemical & Engineering News, Sept 30, 2013.

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21 The near-by Village of Painted Post is appealing a March 2013 court decision favoring the Sierra Club and People for a Healthy Environment. The court issued an injunction against the Village s sale of up to a million gallons of groundwater/day to fracking operations in Pennsylvania. The Village anticipated earning $2.5 million/yr. The trial judge ruled that Village officials improperly conducted their environmental impact review.

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