Elucidating water contamination by fractu

fluids and formation waters from gas wellfluids and formation waters from gas well

integrating isotopic and geochemical trace

A V h N th 

EPA workshop onfracturing fluid composition,February 2011

Avner 

Vengos

h, 

N

athan

Stephen Osborn, Rob Ja

February 2011

Nicholas School of the EDuke University
Shale basins in the USA

The MaThe Ma
Tracing fracturing fluids and co-pro

formation waters 

Disposal to surface wDisposal to surface wDeep water displaceme
Nature of geochemical and isotopic tra

i

δ18O, 

δ

2

H

Water 

isotopes Water chemistry

(geochemical 

fingerprinting)

Isotopes of dissolved co

(11B/10B, 87Sr,86Sr, 238U/234U, ( 

1. Conservative versus non-conservative tracers2. Sensitivity to mixing, dilution effects
The objective of this talk:

Evaluate the potential and applicability of different geochemical and isotopic tracers for tracing the impactfracturin

g fluids and coproduced waters on water reso

Gas well, Dimock, PA
The research methods:

Duke Research activities (updated February 2011):1. Sampling ~70 shallow private wells in eastern PA, NY;2. Sampling 2 producing wells from PA and NY;3. Analysis of brines from the Marcellus Shale; 3. Analysis of brines from the Marcellus Shale;

4. Analysis of flowback effluents from a Marcellus gas we(provided by USGS);

3 Ch i l ( j d t l t ) d i t i (87S 3. Chem

ica

l

(major an

d

trace e

lemen

t

s

) an

d

iso

top

ic 

(87

S

r

δ18O, 

δ

2H) measurements.
Upper Devonian Catskill
Triton@Du

NIST SRM 987 Sr standard

30

NIST SRM 987 Sr standard

25152010

Mean = 0.71024

5

ST= 9.31x10-6 (0n=98

0

0.71022 0.71023 0.71024 0.71025 0.71026

87Sr/86Sr ratio http://www.nichol
Triton@

NIST SRM-951 boric acid

6070

Triton@

5060 Mean = 4.0051

ST= 0.0026 (0.n=238

304020

0

10

3.999 4.001 4.003 4.005 4.007 4.009

11B/10B ratio http://www.nicholas.duke.edu
80

Chemistry of background groundwater: 

if

70

Catski

aqu er

5060

mg/L)Duke sampling 1980s data*

3040

dium (m

20

So

0

10

0 10 20 30 40 50 

* Taylor LE (1984) Groundwater Resources of the Upper Susquehanna River Basin, Pennsylvania (Pennsylvania Department of

Chloride (mg

Pennsylvania (Pennsylvania Department of

Environmental Resources-Office of Parks and Forestry - Bureau of Topographic and Geologic Survey Water Resources Report 58).
First indication for contamination by fr

fluids and co

-produced formation wate

100000

Appala

chian 

brines

fluids and co

-produced formation wate

10000

pp c b es

(Osborn data)

L)

1000

m (mg/

100

Sodiu

10

Catskill Fm

1

0 1 10 100 1000 10000 1

Chloride (mg/L)
Multiple salinity sources

Road salt deicin

g Domestic waste water, Acid-mi

Septic tanks 

Water salinization Natu

grou

M ll b i Mace Fracking fluids Coal ash 

llus 

b

r

ines
Multiple salinity sources with distinguished chemical 

Road salt deicin

g Domestic waste water Acid-mi

Septic tanks 

Na-Cl water typeNa/Cl

=

1 Na-Cl water type / l h h Ca-SO

4 

Na/Cl 1, B/Cl

-hig

Br/Cl, B/Cl-low Na/C

l

≥1, NO

3

-

high

Br/Cl-low, B/Cl-high

B/Cl hig

Coal as

Macellus brines Fracking fluids

Ca-SO 

4 

High CaB/Cl- ve

Ca-Cl water typeNa/Cl<1, 

B

r/Cl, B/Cl

-high

High Ca, Sr, B, Ba

/Cl, /Cl

?
The water isotopes

-58

Castskill Fm Catskill Formation

-62-60

LMWL

-64

δ

2

H

-66

70

-68-

-11 -10.5 -10 -9.5 -9

δ18O
Indication for flowback and formation 

E ih t f 18O d

2H dl 

-30

Appala

chian 

brines

Enr

i

c

hmen

t o

f 18

O an

d

2

H, an

d a 

lower 

-40-35

slope

~

3

pp c b es

(Osborn data)

-50-45

2

H

slope

3

60

-55

δ

2

C t kill F

-65-60

Cas

t

skill

F

m

Slope ~8

-70

-10 -8 -6 -4 -2 0

δ18

O
Minor and trace elements

60 20050

150

3040

on (μg/L) 100

um (μg/L)

1020

Boro

50

Bariu

0

0 10 20 30 40 50

Lithium (

μg/L)

0

0 100 200 300 400 

Lithium

(

μg/L) Strontium 

Strontium
Flowback effluents mixed with Marce

bi (M d #4 DOE/USGS 

160000017000001800000

L)

6000070000

L)

b

r

ines 

(

Mea

dows #4, DOE/USGS sam

12000001300000140000015000001600000

ntium (μg/L 30000 40000 50000

oron (μg/L

1800000

100000011000001200000

0 5 10 15 20 25

Stron

1000020000

-5 0 5 10 

Bo

80000

14000001600000

m (μg/L) 60000 70000

m (μg/L)

800000

10000001200000

Barium

300004000050000

Lithium

0 5 10 15 20 25

30000

0 5 10 

Flow time (days)
Strontium isotopes

0 71550.7160

Catskill Formation

0.71500.7155

ios

Catskill Formation

0.71400.7145

86

Sr rati

0.71300.7135

87Sr/8

0.7125

0 200 400 600 800 1000

Strontium (μg/L)
Elucidating between mixed fracturing-form

0.71200

g g

waters and the Marcellus brines

0.71150

86

Sr ratio Mar

0 711200.71140 Marcellus Shale

0.71100

87Sr/8 20% 

0.710800.711000.71120

r/

86Sr

0.71050

0.710200.710400.71060

87

Sr

F ki fl id Fracturing fluids

0.71000

0 500000 1000000 15000

D

Strontium (μg/L

Fracking fluids

0.71000

0 5 10 15 20 25

Fracking fluids

Sampling day

Fracturing fluids

Fracturing fluids

Strontium (μg/L
Strontium isotopes: a sensitive tracer fo

with fracturing fluids/flowback water

0.71600

with fracturing fluids/flowback water

0.714000.71500 Catskill Fm

atio

0.71300

r/

86Sr ra

0.71200 Marcellus Shale

87Sr

0 710000.71100

Utica Shale

Frackin

g fluid 

(da

y 0

) A lowe

0.71000

10 100 1000 10000 100000 1000000 10000000

g ( y)

Strontium (

μg/L)

non-mifluids
The sensitivity of strontium isotopes to mixing with 

fracturin

g fluids and backflow brines

0 713000.713500.712500.71300 Catskill Fm groundwater0 11 00.71200

Sr/86Sr

0.711000.711

5

0

87S Marcellus Sh

0 710000.71050

Fracturing fluids-form

Fracking fluid (

0.71000

10-10 10-8 10-6 10-4 10-2 10

0

Fraction of contaminated water
Boron isotopes

30

Catskill aquifer

25

mil)

20

B (perm δ11B ={( [11B/10B]sample/[11B/10B]

15

δ

11

B

STD=NIST SRM-951 boric ac

10

0 100 200 300 400 500

Boron (μg/L)
Boron isotopes: differentiation from othe

contaminant sources

35

Marcellus Shale

contaminant sources

30

il)Frackin Flowback fluids g + Marc

25

(per-mi

g

 mix

Flowback fluids

20

δ

11B 

Domestic waste water;

δ11

B

~

0-10 per m

1015

Domestic waste water;

δ B 0 10 per m

Coal, coal ash; 

δ11B

10

1 10 100 1000 10000 100000

Boron (

μg/L)
Boron isotopes: differentiation from othe

contaminant sources contaminant sources

40

Marcellus shale

2030

il)

Catskill groundw

Fracturing+brines mix

10

(per-mi Domestic waste waterδ

0

11B 

20

-10

Coal, coal ash leaching

-

0 0.01 0.01 0.02 0.02 0.03

1/B (L/mg)
Tracing the impacts of gas-well drillin

fracturing fluids fluids on water resofracturing fluids fluids on water reso

Major 

chemistry

Minor and 

trace elements

Water isoto

δ18O, 

δ

2

H

87Sr/86

δ Sr 228Ra/226Ra 11

B

222Rn

The key points: 1)Inte

gration of multiple tracers;

2)Establish geochemical and isotopic base

back

ground 

groundwater prior to 

gas dril