Considerations for hydraulic fracturing and groundwater and surface water protection: lessons learned in the U.S. Robert W. Puls, Ph.D. Director, Oklahoma Water Survey University of Oklahoma
Hydraulic Fracturing in U.S. 1 2 Background Lessons Learned & Risk Management Options 3 U.S. EPA Study
What has changed over the last several years? Extraction of energy resources from shale is becoming more prevalent due to: Advances in horizontal drilling technologies Improved frac fluids, improved extraction efficiency Access to unconventional formations (shale) Reported incidents have increased concerns about potential endangerment of drinking water supplies 3
Hydraulic Fracturing in Shale 9/25/2012 4
EPA/600/R-11/122 November 2011
Typical Gel Frac Chemicals Acid (HCl) 13970 L Friction reducer (mineral oil) 9990 L Surfactant (isopropanol) 9650 L Gelling agent (guar) 6360 L Scale inhibitor (ethylene glycol) 4880 L Breaker (ammonium persulfate) 1140 L Crosslinker (borate salt) 790 L Corrosion inhibitor (N,n dimethyl formamide) 230 L Biocide (glutaraldehyde) 120 L Foaming agent (2-butoxyethanol) *assumes 11,400,000 L gel frac and about 0.5% chemical added volume
Frac Focus (http://fracfocus.org) Chemical Disclosure Registry, Ground Water Protection Council (OKC) Hydraulic fracturing process Casing & cementing State regulations Chemical usage Type Amount >160 companies >12,000 wells
Lessons Learned & Risk Management Options
Analysis of Reports of Suspected Water Resource Impairments from Hydraulic Fracturing 40 sites/locations 10 different states in U.S. 28 sites in shale formations (5 different plays) 8 in tight sands 4 in coal bed methane
Summary of findings for 40 sites of reported suspected incidents Number of Incidents 20 15 10 5 0
Potential Risk Pathways Mismanagement of wastewaters on surface Pit leaks, spills, recycling operations, transport, disposal Inadequate well construction Poor cement job, insufficient casing, inadequate casing Migration of frac fluids to abandoned wells Migration of frac fluids to nearby USDWs
Osborn, et al. 2011. PNAS 108(20): 8172 Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing
Risk Management: Site Selection and Well Pad Construction Identify shallow gas producing zones, base of fresh water Use physical containment on site to protect against runoff, spills, blowouts etc. Sample water wells in immediate area to determine baseline water quality Identify source water locations Evaluate competing uses of source water, time of withdrawals
Potential Monitoring Parameters for Baseline Sampling Program General Inorganic/Metal Parameter Analytes Organic Analytes Microbiology Alkalinity Arsenic DRO, GRO Total coliform/e. Coli Redox potential Barium Methane ph Boron Ethane Specific Calcium Propane Conductance Total dissolved solids Chloride Iron Manganese Nitrate, Nitrite Potassium Sodium Strontium Sulfate
Risk Management: Well Construction Preliminary findings suggest effective reduction in risk to water resources should be focused on proper well construction methods and confirmation of well integrity Surface Conductor casing Surface casing Production casing Wellhead Cement Aquifer Cement Cement Production tubing 1,000 2,000 3,000 4,000 5,000 6,000 Bold lines are pipes 7,000 feet Hydrocarbon-bearing formation
Risk Management: Wastewater Management Findings also suggest improvements can be made to wastewater management on the surface use tanks if possible rather than pits Recycling of wastewater reduces adverse environmental impacts and can reduce costs
Recycling Flowback/Produced Wastewater Up to 18 Mil L water used per well Several companies are now recycling wastewaters Most simply filter wastewater and mix with freshwater; some looking at more complete treatment/reuse options e.g. Chesapeake AquaRenew program Filtration and dilution Evaporative reduction and solidification system http://www.layneintevras.com/evras.html
Risk Management Options Hydraulic fracturing near a drinking water aquifer probably not a good idea Pavilion Draft Report, EPA, Dec 8, 2011
EPA Study: Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources Office of Research and Development US Environmental Protection Agency Washington, D.C. November 2011
Purpose of EPA s Study To assess whether hydraulic fracturing can impact drinking water resources If so, to identify the driving factors that affect the severity and frequency of any impacts
EPA/600/D-11/001/February 2011/www.epa.gov/research
Research Approach Analysis of Existing Data Laboratory Studies Modeling/Scenario Evaluations Toxicological Studies Case studies
Purpose of Case Studies To evaluate potential impacts of hydraulic fracturing in different parts of the US Retrospective case studies = locations where impacts reported or suspected Prospective case studies = collaborate with industry partners to evaluate best management practices to protect water resources
Retrospective Case Study Approach A Tiered Approach Using Adaptive Management Methods Evaluate existing data and information Site visits, stakeholder input and participation Conduct initial environmental sampling and testing Develop site conceptual models for exposure analysis Collect additional samples, testing (geophysical) and more comprehensive analysis including stable isotopic analyses Perform modeling, assess uncertainties
Killdeer, ND Retrospective case study: Production well failure (blowout) while performing 5 th stage of 19-stage horizontal frac Formation: Bakken Shale Possible Impacts: Contamination of USDW, soils Status started summer 2011 1/20/2011
Washington County, PA Retrospective case study: Reported impoundment leaks, spills Formation: Marcellus Shale Possible Impacts: Contamination of USDW, streams, soils Status Started in Fall, 2011 1/20/2011
Retrospective case study: Wise County, TX Reported spills, leaks, degraded water quality of private wells Formation: Barnett Shale Possible Impacts: Contamination of USDW, surface water Status Started Summer, 2011 1/20/2011
Raton Basin, CO Retrospective case study: Degradation of water quality in private wells, high methane concentrations in wells, explosion at wellhead Formation: Raton Basin, shallow CBM Possible Impacts: Contamination of USDW Status Started Fall, 2011 1/20/2011
Bradford/Susquehanna Counties, PA Retrospective case study: Reported spills, tank leaks, methane in private wells Formation: Marcellus Shale Possible Impacts: Contamination of USDW, streams, soils Status Started Fall 2011 1/20/2011
Prospective Case Study Approach 2 locations, conducted in collaboration with industry partner Full life cycle of water usage Evaluate existing data and information Conduct baseline environmental sampling, testing Develop site conceptual models for potential exposure Conduct environmental sampling following pad and well construction Collect time series samples of flowback water Conduct environmental sampling following hydraulic fracturing operations Collect additional samples over time during resource production
SUMMARY Hydraulic Fracturing together with horizontal drilling has greatly improved the efficiency and profitability for shale gas and oil resource extraction. While there have been some reported incidents potentially impacting water resources, improved surface management and better regulatory oversight can significantly reduce risks to water resources FracFocus and other initiatives are improving state-ofthe-practice for environmental protection and transparency Baseline water quality data is important for adequate assessment of impacts
Research Needs Better cement formulations for increased pressures and longer lifetime Better understanding of microbiology of deep subsurface and produced waters Continued development of green chemicals for hydraulic fracturing Continued development of recycling to minimize water usage Assessment of methane in water regarding human health impacts
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