3/1/2017
LINES OF EVIDENCE FOR EVALUATING
POTENTIAL IMPACTS FROM PRODUCED WATER
ON GROUNDWATER
GWPC UIC Conference, Austin TX
John Connor, P.E., P.G., BCEE
Lisa Molofsky, P.G.
Ileana Rhodes, PhD
Ann Smith, P.E., BCEE
22 February 2017
IDENTIFYING A PRODUCED WATER IMPACT
Indicators of a Produced Water
Impact:
Cl -
Na +2
TDS
CHALLENGE: Increases in Cl, Na, and TDS can
be related to causes other than a produced
water impact.
KEY
Geochemical and isotopic methods can
POINT: differentiate source(s) of salinity.
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SOURCES OF PRODUCED WATER IMPACTS:
Conventional Wells
Unconventional Wells
• Spills of flowback water
Historical produced
water pits
• Improperly disposed
flowback water
Injection wells
Improperly plugged and
abandoned wells
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OTHER POSSIBLE CAUSES FOR INCREASED SALINITY
IN GROUNDWATER:
Other Salinity Sources:
Naturally occurring
saline groundwater
Upconing of
deeper water
Seawater
Halite Solution
Road Salt
Agriculture
Before
After
Effects of Storm Surge: Louisiana from
space before and after hurricane Rita
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OTHER POSSIBLE CAUSES FOR INCREASED
SALINITY IN GROUNDWATER:
Changes in salinity within a water supply well over
multiple sampling events:
Wells may be fed by
multiple fractures and/or
aquifers.
Changes in water usage,
well depth and water table
can alter mixing dynamics
within a well.
Source: CSG Geotechnical Services
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OTHER POSSIBLE CAUSES FOR INCREASED
SALINITY IN GROUNDWATER:
Composition of Different Waters in Appalachian Basin:
Groundwater from restricted flow fractures
commonly contains naturally elevated salinity
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TIERED EVALUATION APPROACH TO
IDENTIFYING SOURCE OF SALINITY
Challenge with Investigations:
Source(s) of salinity difficult to
distinguish
Numerous evaluation
techniques
Best tool dependent on sitespecific characteristics
Multiple lines-of-evidence may
be needed
KEY
Match level of effort and complexity of
POINT: evaluation to site-specific conditions.
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TIERED EVALUATION APPROACH
Tier 1: Initial Screening Process
Is there a salinity impact, and if so, is the
source easily identified?
Tier 2: Basic Geochemical Analyses
Can the major and trace ionic composition identify
the source(s)?
Tier 3: Advanced Geochemical Analyses
Are there advanced isotopic and geochemical
analyses that can identify the source(s)?
KEY
Match level of effort and complexity of
POINT: evaluation to site-specific conditions.
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TIERED EVALUATION APPROACH
TIER 1:
INITIAL SCREENING PROCESS
TDS or Cl
Below
Applicable
Criteria
No
TDS
or Cl
< Background
Yes
No
TIER 2:
BASIC GEOCHEMICAL
ANALYSIS
Source of
Elevated
Salinity
Conclusive
Yes
No
Basic
Geochemical
Analyses
Conclusive
Yes
TIER 3:
ADVANCED
GEOCHEMICAL ANALYSIS
Advanced
Geochemical
Analyses
Conclusive
No
Yes
No
Yes
NO FURTHER EVALUATION WARRANTED
ADDITIONAL DATA/ REVISED METHODS
PENDING PUBLICATION:
Paquette et al., 2017 (Groundwater Journal)
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Chloride Conc.
TIER 1: INITIAL SCREENING PROCESS
BACKGROUND
CRITERIA
NO INJURY
NFA
SOURCE
CONCLUSIVE
MANAGEMENT
SOURCE
INCONCLUSIVE
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TIER 2
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TIER 2: BASIC GEOCHEMICAL EVALUATION
Plots of Major Ions and Trace Ions
Basic Visualization Techniques
Piper
Durov
Schoeller
Histogram
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TIER 2: BASIC GEOCHEMICAL EVALUATION
Plots of Major Ions and Trace Ions
Basic Visualization Techniques
Stiff
Radial
Circular
Bar
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TIER 2: BASIC GEOCHEMICAL EVALUATION
Plots of Major Ions and Trace Ions
Basic Visualization Techniques
K/Cl (Weight Ratio)
Bivariate
0.1
Bivariate
Background
Aquifer
Seawater
0.01
Produced
water
Common Major
and Trace Ions:
Cl, Na, Ca, Br, K,
Mg, I, SO4, Sr, B, Li
Common Ion
Ratios:
0.001
100
1000
10000
100000
Cl (mg/L)
Ions and ion ratios are commonly plotted
against chloride.
Powerful for identifying mixtures & small
contributions from a salinity source.
Cl/Br, Na/Cl, K/Cl,
Sr/Cl, I/Cl, SO4/Cl,
Ca/Mg,(Ca+Mg)/SO4,
(Ba+Sr)/Mg
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TIER 3: ISOTOPES
Isotopes of Water: δ2H and δ18O
Local Meteoric Water Line (LMWL) represents the δ2H and
δ18O values of meteoric water in a localized area.
30
δD-H2O (‰ VSMOW)
20
10
0
-10
-20
Groundwater and
Surface Water:
-30
-40
Typically plots on LMWL
-50
-8
-3
2
δ18O-H2O (‰ VSMOW)
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TIER 3: ISOTOPES
Isotopes of Water: δ2H and δ18O
Local Meteoric Water Line (LMWL) represents the δ2H and δ18O
values of meteoric water in a localized area.
30
δD-H2O (‰ VSMOW)
20
10
0
-10
Produced Water:
-20
Typically formed in
evaporative basins,
plots below the LMWL
-30
-40
-50
-8
-3
2
δ18O-H2O (‰ VSMOW)
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TIER 3: ISOTOPES
Strontium Isotope Ratio: 87Sr/86Sr
Application:
The 87Sr/86Sr ratio is a good diagnostic parameter
Application:
in evaluation of potential
impacts to GW from
produced water or other shallow zones of salinity.
87Sr/86Sr
ratio of
Marcellus produced
water versus other
formations in
Appalachian Basin.
Adapted with permission from: Chapman et al., 2012, ES&T
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TIER 3: ISOTOPES
δ13C of Dissolved Inorganic Carbon (DIC)
δ13C of DIC is highly enriched in
Application:
some produced water.
Application:
Marcellus
δ13C-DIC values of
various waters in
the Appalachian
Basin.
δ13CDIC (‰VPDB)
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Groundwater
10
0
-10
-20
Marcellus
Shale
Groundwater Coal Mine
Upper
Devonian Formations Discharge
Shale
Surface
Waters
Sharma et al., 2013, Groundwater Journal
TIER 3: ISOTOPES
Radium Isotopes: Ra-228/ Ra-226
Application:
Ra-228/ Ra-226 ratio can differ
significantly
in produced water
Application:
vs. other water sources.
Marcellus Produced Water
PA Non-Marcellus Waters
Ra-228/ Ra-226:
Ra-228/ Ra-226:
Typically <0.3
Typically >1
Ref: Rowan et.al, 2010, USGS Scientific Investigations Report 2011–5135
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Other Isotopes
Common Application
Isotopic Analysis
Tracing sources of salinity
and water sources with
different evolutionary
histories:
δ34S, δ37Cl,
δ81Br, δ11B
Age dating of groundwater:
3H, 14C
Dating older waters and
tracing sources of salinity:
129I, 129I/127I
Advantages:
Holding time of several years.
Disadvantages:
Reference data may not exist for
comparison, some analyses are
expensive and have longer
turnaround times.
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REFERENCES
Paquette et al. 2017 (Pending). A Tiered Approach to Evaluating Sources of Salinity in Water at
Oil and Gas Production Sites. Groundwater Journal.
Chapman et al. 2012. Geochemical and strontium isotope characterization of produced waters
from Marcellus Shale natural gas extraction. Environmental Science & Technology.
Sharma et al. 2013. Isotope Approach to Assess Hydrologic Connections During Marcellus
Shale Drilling. Groundwater Journal.
Rowan et al. 2011. Radium content of Oil- and gas-Field Produced Water in the Northern
Appalachian Basin (USA): Summary and Discussion. USGS Scientific Investigations
Report 2011-5135.
Richter and Kreitler. 1991. Identification of Sources of Ground-Water Salinization Using
Geochemical Techniques. United States Environmental Protection Agency EPA/600/291/064.
Williams et al. 1998. Hydrogeology and groundwater quality of the glaciated valleys of
Bradford, Tioga, and Potter Counties, Pennsylvania. USGS Water Resources Report No.
68.
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John Connor, PE, PG, BCEE
Lisa Molofsky, P.G.
Ileana Rhodes, PhD
Ann Smith, PE, BCEE
21 February 2017
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LINES OF EVIDENCE FOR EVALUATING POTENTIAL IMPACTS
FROM PRODUCED WATER: OUTLINE
1
Indicator parameters
2
Diagnostic cations and anions
3
Stable isotopes of water: δ2H and δ18O
4
Strontium isotopic ratios: 87Sr/86Sr
5
δ13C of dissolved inorganic carbon (DIC)
6
Ra-228/Ra-226 and other isotopes
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Tiered approach to identifying source of salinity
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