Microbial Ecology of Hydraulic Fracturing: Implications for Sustainable Resource Development

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1 Microbial Ecology of Hydraulic Fracturing: Implications for Sustainable Resource Development Irvine, CA September 13, 2014 Prof. Kelvin B. Gregory

2 Evolution of Oil and Gas Development On the banks of the Youghigheny River, Versailles, PA, Photo Courtesy: McKeesport Historical Society. Located and Digitized by Prof. Joel Tarr, Carnegie Mellon University.

3 Natural Gas-bearing Shale Gas trapped in pores or adsorbed to surfaces in low permeability rock. Commercial production requires engineering permeability Enabled by: Horizontal Drilling / Hydraulic Fracturing

4 Overview of Horizontal Drilling Walking Rig Multiple wells on same pad

5 Horizontal Drilling: Economic and Environmental Advantages Vertical Wells (pink) many pad sites Horizontal Well (green) single pad site Centralized Operations, Less Land Disturbance, Lower Construction Costs

6 Hydraulic Fracturing: Water Utilization 1000 m 1500 m 2000 m Fracturing Fluid contains 4-20 million liters of water mixed with sand and chemicals that protect well and optimize gas production. Produced Water returns to the surface and is stored prior to treatment and reuse, or disposal m

7 Produced Water Characteristics Flow rate (m 3 /d) Flowrate TDS Time of Flowback (days) TDS Concentration (g/l) maximum average TDS (mg/l) 345, ,390 oil and grease (mg/l) TOC (mg/l) SO 4 (mg/l) Cl (mg/l) 196,000 57,447 Na (mg/l) 117,000 24,123 Ca (mg/l) 41,000 7,220 Ba (mg/l) 13,800 2,224 Sr (mg/l) 8,460 1,695 Fe total (mg/l) Ra 226 (pci/l) 9, U 238 (pci/l) Gregory et al, Elements (2011); Barbot et al, Environ Sci Technol (2013)

8 Water Management Hurdles in Pennsylvania Disposal Deep-Well Reinjection Few in PA Dilution into WWTP Contamination Ag Reuse Too salty Treatment Membrane Technology $$$ Thermal Distillation $$$$ Freeze Thaw Evaporation Bad Climate Artificial Wetlands Too salty Local Challenges Innovation & Local Solutions

9 Reuse of Produced Water for Hydraulic Fracturing Hydraulic Fracturing with Recycled PW Dilute to Make-up volume; add Chems Produced Water to Impoundment Impacted/Low-Quality Water as Make-up and Dilution (Abandoned Mine Drainage) Pretreatment Remove Solids and M2+.

10 Centralized Impoundments, Long Storage Impoundment for Single Well Pad Centralized Impoundments for Multiple Well Pads Microbial communities Thrive on substrates & nutrients in the produced water Evolve with time Alter the geochemistry in the impoundment and in the well Drive management decisions and costs

11 Microbes and Biogeochemistry of Produced Water Microbial Community from Wellhead Introduced to Impoundment Microbial Community from Impoundment Introduced to Next Well During Recycling BIOCIDES SO 4 2- Organics CO 2 Fermentation S 0 Malodorous Compounds H 2 S Solubility of Metals Fe 3+ (s) U 6+ (aq) Fe 2+ (aq) U 4+ (s) Biocorrosion Questions: Which bacteria are present? Where? When? What can they do? Approach: Next Generation Sequencing for High-resolution Insights

12 Generating Metrics for Ecological Comparisons Cells DNA Gene encoding ribosomal RNA DNA sequencing Compare to Database Isolate DNA PCR Sequence analysis Generate phylogenetic tree Bacteria Archaea Eukarya You Are Here Your Breakfast was Here

13 Wellheads

14 Dynamic Populations in Wellhead Samples Order (Class) Rhodobacterales (Alphaproteobacteria) Sphingomonadales (Alphaproteobacteria) Caulobacterales (Alphaproteobacteria) Rhodospirillales (Alphaproteobacteria) Pseudomonadales (Gammaproteobacteria) Vibrionales (Gammaproteobacteria) Alteromonadales (Gammaproteobacteria) Chromatiales (Gammaproteobacteria) Campylobacterales (Epsilonproteobacteria) Burkholderiales (Betaproteobacteria) Thermoanaerobacterales (Clostridia) Halanaerobiales (Clostridia) Clostridiales (Clostridia) Bacteroidales (Bacteroidetes) Flavobacteriales (Flavobacteria) Fusobacteriales (Fusobacteria) Bacillales (Bacilli) Lactobacillales (Bacilli) Sample name SW FF FB1 FB7 FB9 PW 0% >0-5% >5-10% >10-20% >20-30% >30-50% >99% Diversity sharply decreases Anaerobic, fermentative and sulfur-reducing populations emerge At the expense of the aerobic and phototrophic Dominant species in PW is present in source water Murali Mohan et al, Environ Sci Technol (2013)

15 Functional Metagenome Reveals How Capabilities of Community is Changing Organic Carbon Organic Carbon Carbohydrates Sugars Polysaccharide Amino Sugar Metabolism Stress Response Sulfur Metabolism Oxidative Stress Heat Shock Osmotic Stress Acid Stress Inorganic Sulfur Metab. Organic Sulfur Metab. Adapting towards organisms that are tough and optimized for survival and proliferation in PW

16 Impoundments

17 Impoundments and Sampling Surface Untreated Middle Bottom Biocide Amended Aerated

18 Geochemical Characteristics/Stratification Chemical Constituents of Water Samples (mg/l) Untreated Biocide Amended Aerated Analyte SUF MID BOT SUF MID BOT SUF MID BOT Ba Ca Total Fe K Na Sr Cl Br I NO - 3 ND b ND ND ND ND ND ND ND ND SO Acetate ND ND ND ND Murali Mohan et al, Microb Ecol (2013)

19 Bacterial Communities in Impoundments Untreated Biocide Amended Aerated Phototrophs Aerobic Metab. Surface Middle (1.5m) Fermentative Sulfur-utilizing Spore-forming Facultative, Aerobic Anaerobic Not sufficiently similar to known Bacteria Bottom (3.5m) Methane-producing Archaea at bottom of untreated and biocide only Murali Mohan et al, Microb Ecol (2013)

20 Take Home Message and Discussion 20 Unique microbial communities arise that are selected for sulfur (not sulfate) metabolism Industry tests to determine sulfide producing potential will yield false negatives The chemistry of produced water selects for tough bacteria that are well-adapted for survival Recycling of produced water carries over tough bacteria into the next frac and may accelerate the onset of well souring

21 Thoughts on Shale Resources & Water Stress Development competes with local municipal, industrial, agricultural, and environmental water resource needs. Recycling of produced water may enable oil/gas development in new regions Solutions arise locally that can have global impacts.

22 Research Frontiers: Microbial Control 22 Engineered Microbial Communities in Subsurface: Optimize Beneficial Populations while Eliminating Detrimental Ones Engineered functionality of existing microbial community: introduction of desired genes into the tough population Botique biocides that target specific populations while leaving others unharmed Design of hydraulic fracturing fluid with the endpoint, desired microbial community in mind

23 Students, Collaborators, Support Radisav Vidic Univ. Pittsburgh Rick Hammack NETL Arvind Murali Mohan Kyle Bibby Univ. Pittsburgh Angela Hartsock NETL