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Prof. Gretchen L. Wainwright, P.E. Civil Engineering Technology, Environmental Management and Safety CAST
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Presentation Topics Hydrofracking Chemicals Wastewater Composition Flowback Water Management Options Stormwater Protection Disposal Options Conclusions
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Water Use Data in Susquehanna Basin Total water use: 716.0 million gallons (6/1/08 to 5/21/10) 209.2 mgal from public water supply (29%) 506.8 mgal from surface water (71%) Average total volume of fluid used per well: 3.3 mgal/well 2.8 mgals of fresh water (85%) 0.5 mgal of reused flowback (15%) Average recovery of flowback: 10.0% (30 day) Total amount of flowback reused or sent to disposal Reuse 44.1 mgals Disposal 21 mgals
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Substances added to water during fracturing process Proppant (frac sand) Friction reducers Foaming agents and antifoam agents Emulsifiers and de- emulsifiers Gellants and gel breakers Biocides Corrosion inhibitors Oxygen scavengers Scale inhibitors pH adjustment agents Surfactants Viscosifiers Cross linkers Stabilizers Iron control Breakers
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Fracture Fluid Composition ADDITIVE TYPEMAIN COMPOUNDPURPOSE Diluted acid (15%)Hydrochloric or muriatic Dissolve minerals and initiates cracks in rocks BiocideGlutaraldehyde Bacterial control Corrosion inhibitorn,n-dimethyl formamide Prevents corrosion BreakerAmmonium persulfate Delays pbreakdown of gel polymers CrosslinkerBorate salts Maintains fluid viscosity at high temperature Friction reducersPolyacrylamide, Mineral oil Minimize friction between the fluid and the pipe Gel Guar gum or hydroxyethyl cellulose Thickens water to suspend the sand
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Fracture Fluid Composition ADDITIVE TYPEMAIN COMPOUNDPURPOSE Iron controlCitric acid Prevent precipitation of metal oxides Oxygen scavengerAmmonium bisulfate Remove oxygen from fluid to reduce pipe corrosion pH adjustment Potassium or sodium carbonate Maintains effectiveness of other compounds ProppantSilica quartz sane Keeps fractures open Scale inhibitorEthylene glycol Reduces depostion on pipe SirfactantIsopropanol Increases viscosity of fluid
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Wastewater Sources Frac flowback water High flows for short duration 10 – 40% of frac fluid recovered Most recovered in first 1-2 weeks TDS quickly climbs to 30,000 – 200,000 mg/L Contains numerous chemical additives and naturally occurring constituents, including NORM Produced Water Lower flows (2 to 30 bpd per well) Potentially very high TDS (100,000 to 300,000 mg/L) Continues to flow for the life of the well
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Flowback Water Cumulative Amount over Time Flow Rate versus Time
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Flowback Water Quality
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Flowback Water Management Options Direct reuse without treatment (blending) Blending of flowback with fresh water for subsequent use Minimal cost with increased potential for well plugging issues On-site treatment and reuse Re-condition water by chemical or filtration treatment Moderate cost with minimized potential for well plugging issues Off-site treatment and reuse High transportation costs with same benefit as on-site treatment Off-site treatment and disposal High transportation and disposal costs
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Water Storage Storage options: Centralized impoundment Single-pad dedicated impoundment Frac tanks Storage based on ultimate scale of operations (long vs. short term)
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NY State SPDES Regulation Proposed Terms for HVHF related to Water Storage Clean water can be stored in surface impoundments (pits) Cuttings resulting from drilling conducted with “air or fresh water” can be stored in pits Flowback water and produced water CAN NOT be stored in surface impoundments Must be stored in a closed-loop system of tanks Volume of a single pit can not exceed 250,000 gals; total volume of pits can not exceed 500,000 gals Pits must be lined
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On-Site Controls to Prevent Stormwater Contamination Operator must apply for coverage under the general HVHF SPDES general permit Covers construction activities, fracturing activities, and post- drilling activities Must have a Stormwater Pollution Prevention Plan (SWPPP) Operator must have a Spill Prevention Control and Countermeasure Plan (SPCC Plan) Closed-loop tank system must be used to manage drilling fluids and cuttings Disposal, recycling or reuse of flowback water must be approved by NYS DEC Transporters must have a Part 364 permit
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SWPPP Requirements Operator must evaluate alternatives for the HVHF additives that are “efficacious but which exhibit reduced aquatic toxicity and pose less risk to water resources and the environment” Secondary containment must be provided Must maintain a list of additives on site Ensure proper transport and disposal of wastewater Structural and non-structural Best Management Practices (BMPs)
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On-Site Treatment Options Blending and dilution with direct discharge (POTWs) No pollutants are removed Chemical treatment pH adjustment precipitation of metals/sulfates Does not remove salts Filtration/Membrane Treatment Micro/nano/ultra-filtration Reverse osmosis Removes many compounds, but membranes can become fouled at higher concentrations Thermal/Evaporative Technologies Can remove virtually all compounds, but very expensive
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Parameters of Concern when Reusing Flowback Water Total dissolved solids (chloride) – interference with friction reducers Total suspended solids – down hole plugging Metals (barium and strontium) – may form precipitates Sulfates and carbonates – may form precipitates Bacteria – down hole plugging
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Ecologix: Integrated Treatment System Mobile DAF system that removes suspended solids, fats, oils and greases from wastewater, produced water, and frac water. It uses chemical and air addition to separate, float and remove sludge.
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FracTreat™ Mobile Precipitation System from Siemens Water Technologies
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On-Site Treatment Necessary to be able to re-use the flowback water Primarily removes dissolved and suspended solids Performed in mobile package-type systems Generally will not adequately treat wastewater to enable direct discharge Technology based discharge requirement under 40 CFR Part 435 – Oil and Gas Extraction Point Source Category is “no discharge of any pollutants from any source associated with production, field exploration, drilling, well completion or well treatment” Sludges generated also require further dewatering and disposal
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Off-Site Treatment and Disposal HVHF SPDES permit applications must include a Fluid Disposal Plan covering the life of the well Requires certification from disposal facility that available capacity exists Identifies alternative and contingent disposal options Contains estimates of chemical concentrations of flowback and production water over the life of the well Identifies all chemical additives to be used by name, purpose and type, and amount MSDSs for additives included
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POTW Requirements Before a POTW can accept Flowback Water it must: Have an approved pretreatment program Notify DEC of intent to accept flowback water Perform a headworks analysis that demonstrates that the POTW can remove the contaminants expected to be present, including TDS, NORM, Ba, Br, BTEX, and other additives Submit to a permit modification to include appropriate monitoring and effluent limits
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Flowchart for acceptance of High Volume Hydraulic Fracturing (HVHF) wastewater by publicly owned treatment works (POTWs)
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Conclusions NYS DEC has done a good job developing requirements that will ensure: adequate and appropriate treatment of flowback and produced water the protection of stormwater throughout all phases of well construction and operation the protection of water resources Hardest part is yet to come – implementation and oversight of these regulations
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References Siemens Water Technologies, Warrendale, PA. FracTreat and Simatic are trademarks of Siemens, its subsidiaries or affiliates. http://www.water.siemens.com/en/oil-gas/upstream/fractreat/Pages/default.aspx http://www.water.siemens.com/en/oil-gas/upstream/fractreat/Pages/default.aspx Ecologix Environmental Systems, Alpharetta, GA http://www.ecologixsystems.com/system-its.php http://www.ecologixsystems.com/system-its.php “Water Treatment Solutions for Marcellus Natural Gas Development”, presentation by David Yoxtheimer, P.G., PennState Marcellus Center for Outreach and Research. “Sustainable Water Management for Marcellus Shale Development”, presentation by Radisav D. Vidic, Ph.D., PE, Department of Civil and Environmental Engineering, Swanson School of Engineering, University of Pittsburgh. Proposed Express Terms 6 NYCRR Parts 750.1 and 750.3, Obtaining A SPDES Permit and High-Volume Hydro Fracturing (HVHF), http://www.dec.ny.gov/regulations/77383.html http://www.dec.ny.gov/regulations/77383.html Revised Draft SGEIS on the Oil, Gas and Solution Mining Regulatory Program (September 2011) http://www.dec.ny.gov/energy/75370.html http://www.dec.ny.gov/energy/75370.html
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