480 likes | 689 Views
Environmental Forensic Investigation of Hydraulic Fracturing Fluids used in Shale Gas Wells in the Eastern United States. Frank L. Dorman , Jessica Westland Penn State University.
E N D
Environmental Forensic Investigation of Hydraulic Fracturing Fluids used in Shale Gas Wells in the Eastern United States Frank L. Dorman, Jessica Westland Penn State University
Environmental Forensic Investigation of Hydraulic Fracturing Fluids used in Shale Gas Wells in the Eastern United StatesInitial Investigations Frank L. Dorman, Jessica Westland Penn State University
Shale Gas Wells in Eastern US: • Marcellus Shale: • Gas producing formation between 4000 to 8500 feet from surface • “Reachable” in PA, NY, OH, WV, and part of Ontario • Rapid increase in drilling in last three years • Property owners are leasing land to drilling companies • Receive money based on amount of extracted gas • Drilling companies have received tax benefits • Surge has out paced ability to understand and control potential impacts
Chemicals Used by Hydraulic Fracturing Companies in Pennsylvania For Surface and Hydraulic Fracturing Activities (PA DEP website)
Texas Company Pays $208,625 in Settlements for Polluting Creeks in Clearfield County Associated Press Houston, PA Oct 29,2008
Gas well steps: • Well is drilled • Horizontal boring in vein • Casings are installed • Hydraulic fracturing • Pressure release • Collection of Blowback water • Disposal of collected material • Recent procedure • Not all material is collected
Casing structure and well depth should allow for minimal contamination • Reports of casing breeches and surface water exposure reported • Drill sometimes passes through abandoned mine shafts
Companies are “Self Reporting” • Range Resources • Halliburton • What is actually reported is not specific
Sample Preparation • VOC’s • SPME • SVOC’s • QuEChERS extraction • Liquid/Liquid ABN extraction • Automated sample preparation (J2 Scientific)
QuEChERS • Anastassiades and Lehotay developed the QuEChERS (“catchers”) method for high aqueous samples (foods) • Quick • Easy • Cheap • Effective • Rugged • Safe
QuEChERSMethodology • Procedure • Sample (matrix) • Extract with appropriate solvent (ACN) • Phase separation • Salt addition (pre-dispersive) • Further matrix clean-up possible • dispersive-Solid Phase Extraction (d-SPE)
Liquid/Liquid Extraction • ~500 mL aqueous samples • Acid preserved in field • 3 X 60 mL separatory funnel shakes (2 min each) • Collect extracts • Adjust pH to 10 • 3 X 60 mL separatory funnel shakes (2 min each) • Collect extracts and combine with above • Reduce solvent volume to 1.0 mL using Kuderna-Danish concentration
Analytical Method? • GC-MS or GCxGC-MS rather obvious • Time-of-Flight would be preferred mass spectrometer • Samples may be quite complex • Much easier deconvolution
Gas Chromatograph Conditions • Agilent 7890 • Column: • Restek Rxi-5Sil MS with integral guard • 35M (5M guard) X 0.25 mm i.d. X 0.25 mm df • Injector (splitless): • Splitless, 1 minute hold, 4-mm Sky Uniliner (Restek), hole at top • 250 C • 1.2 mL/min, He, constant flow • Injector (split): • 10:1 split, 4-mm Split liner with SV wool (Restek), standard split seal • 250 C • 1.2 mL/min, He, constant flow • Oven Programs: • QuEChERS – 90 C (1), 12C/min 325 C (10) • Liq/Liq – 40 C (1), 12 C/min 325 C (10)
LecoTruTOF Mass Spec Conditions • Transfer line 250 C • Source Temperature 250 C • 400 sec filament delay • 45 – 550 amu • 10 spectra/sec • ChromaTOF 4.34 used for all instrument control and data processing • NIST 2008 Library for spectral searching
Data Analysis • Sample complexity makes display difficult • Surrogate recoveries were biased high in most samples • 100-300% • Large number of components Identified • 400 to 1500 components/sample • No reference standards • All identifications are tentative, at best • Match of 700 used for searching • S/N of 10:1 used • Likely too low for 500:1 enrichment
Method Blank QuEChERS Extract Liquid/Liquid Extract
Method Blank Compound ID’s Peak # Name 1 Octadecane, 6-methyl- 2 4-(5-Bromo-3-tert-butylsalicyl)-2,6-di-tert-butylphenol 3 Naphthalene, 1,2,3,4-tetrahydro-1,6-dimethyl-4-(1-methylethyl)-, (1S-cis)- 4 5-Ethyldecane 5 PCB 18 (surrogate) 6 PCB 28 (surrogate) 7 PCB 52 (surrogate) 8 Triphenylmethane(surrogate) 9 tris(1,3-dichloroisopropyl) phosphate (surrogate) 10 2-Butanone, 1-(acetyloxy)- QuEChERS Extract Peak # Name 1 Ethanol, 2-chloro-, acetate 2 Ethanol, 2-chloro-, acetate 3 PCB 18 (surrogate) 4 PCB 28 (surrogate) 5 PCB 52 (surrogate) 6 Triphenylmethane(surrogate) 7 tris(1,3-dichloroisopropyl) phosphate (surrogate) 8Cyclotrisiloxane, hexamethyl- 6-Amino-5-cyano-4-(3-iodo-phenyl)-2-methyl-4H-pyran-3-carb.acid ethyl ester 1H-Benzo[4,5]furo[3,2-f]indole Several small siloxane-related compounds late in the chromatogram Liquid/Liquid Extract
QuEChERS Extracts Method Blank Reynoldsville Quad Greensburg Quad Worthington Quad Kittaning Quad New Florence Quad
Liquid/Liquid Extracts Worthington Quad Kittaning Quad Reynoldsville Quad Greensburg Quad New Florence Quad
Reynoldsville Quad - 1093 peaks Few OH’s QuEChERS Extract Sulfur’s Liquid/Liquid Extract Aliphatics, OH’s, esters, COOH’s, etc… PCB 28 Heavier OH’s Mid OH’s Sulfur
Greensburg Quad – 585 peaks Alkoxy OH Alkoxypyrole QuEChERS Extract OH’s Alkoxy OH, Alkanes Liquid/Liquid Extract Acids, Esters, aliphatics PCB 28
Worthington Quad – 944 peaks Sulfurs, acids, OH’s QuEChERS Extract OH OH OH Aliphatic acids Liquid/Liquid Extract PCB 28
Kittaning Quad – 959 peaks QuEChERS Extract Mostly aliphatic alkane Hexagol, aliphatics, oxy-aliphatics Liquid/Liquid Extract Glycols, OH’s PCB 28 Esters and OH’s
New Florence Quad – 883 peaks hydrocarbons QuEChERS Extract Glycols Liquid/Liquid Extract Aliphatics Aliphatics and OH’s
New Florence Quad QuEChERS Extract Liquid/Liquid Extract
Peak # Name R.T. (s) Similarity 405 Cyclohexane, 1,2,3-trimethyl-, (1à,2à,3à)- 1193.8 787 406 Undecane, 2,6-dimethyl- 1194.4 805 407 Fumaric acid, decyl pent-4-enyl ester 1194.9 783 408 Adipic acid, 2-ethylcyclohexyl isohexyl ester 1196.3 881 409 Octadecanamide 1196.7 919 410 Sulfurous acid, butyl 2-ethylhexyl ester 1197.9 737 411 Fumaric acid, eicosyl trans-hex-3-enyl ester 1199.2 939 412 Dichloroacetic acid, 1-cyclopentylethyl ester 1199.6 785 413 1,5,9,13-Tetradecatetraene 1200 728 414 7,9-Dimethyl-8-nitrobicyclo[4.3.1]decan-10-one 1200.4 822 415 Tridecane, 2,5-dimethyl- 1201.7 973
Mid-point Summary: • Analytical methodology is acceptable, but generally results in chromatographic overload • Sample preparation seems to require liquid/liquid extraction, but this is time-consuming • Samples all appear different, but many, many more samples need to be evaluated • Preparation technique must be adapted • Automated Sample preparation, coupled with split injection?
Automated Liquid/Liquid ExtractionJ2 Scientific PrepLink • 100 (up to 500) mL aqueous samples • Acid preserved in field (same as previous) • Acid Fraction and Base Fraction separated • Sample split, and \pH of base fraction adjusted to 10 • Each Fraction extracted using C18/DVB • Dichloromethane elution (20 mL) each • Point of further method developement • Collect extracts and combine • GPC cleanup (sulfur removal) • Reduce solvent volume to 1.0 mL AccuVap module
Liquid/Liquid Extracts Worthington Quad Kittaning Quad Reynoldsville Quad Greensburg Quad New Florence Quad
Liquid/Liquid Extracts – Split Injection Worthington Quad Kittaning Quad PCB 28 S/N = 19:1, 5 pg Reynoldsville Quad Greensburg Quad New Florence Quad
Reynoldsville and Kittaning Samples, Sister Wells Early Eluters Unknown Aliphatic Acid Later Eluters “Unknown”
Conclusions • QuEChERS extraction was mildly successful in determination of very large differences • Did not work well on high MW polar compounds • Did provide some complimentary information • Liquid/Liquid extraction produces extracts of high quality to allow for characterization • PrepLink (J2 Scientific) will become method of choice • Samples are relatively complex, but each shows differences • Lower sample volumes, split injection • Several of the cited compounds were found, along with many, many others • GC-TOFMS worked well for sample characterization • Quantification ongoing, requires standards!
Continued Work • More samples need to be characterized • Additional sources of blowback water will be investigated • Post wastewater treatment samples under investigation • VOC portion will be added • Automated sample preparation under development • Possible collaboration with the gas-drilling industry being sought • GCxGC-TOFMS being explored • Samples already analyzed
Acknowledgements: • LECO Corporation • Nick Hall, Joe Binkley, Mark Merrick, R.J. Warren • Todd Barton, Ray Clifford • J2 Scientific • Jeff Wiseman, Tom Dobbs • Restek Corporation • Jack Cochran, Gary Stidsen • Penn State University
Thank You Questions? fld3@psu.edu frank@peak-diagnostics.com