IWC

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1 

# Pretreatment Targets for Salt Recovery from

Marcellus Shale Gas Produced Water

JAMES SILVA

RACHEL GETTINGS

WILLIAM KOSTEDT

AND VICKI WATKINS

GE Global Research Center

Niskayuna, NY

KEYWORDS: Marcellus, water, total dissolved solids (TDS), pretreatment, shale gas, hydraulic

fracturing, naturally occurring radioactive materials (NORM), radium, barium, Aspen Plus, OLI,

evaporation, crystallization

ABSTRACT

Much of the Marcellus shale gas produced water contains significant levels of both

barium and naturally occurring radioactive materials (NORM). As the Marcellus continues to be

developed there will be a growing need to recover both water and salt from this high total

‐

dissolved

‐ solids (TDS) produced water. Whether the salt product is disposed of as

nonhazardous solid waste or beneficially used for deicing, the salt must be pure enough to pass

specific regulations with respect to both radium and barium. Based on pretreatment and

crystallization experiments with field produced water as well as Aspen PlusTM/OLI simulations,

we have developed a methodology for defining pretreatment targets for both barium and

radium. The results of this study show that water and salt recovery from Marcellus produced

water is an economically attractive option, particularly for produced water from north

‐ central

and northeast Pennsylvania.IWC

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2 INTRODUCTION

Effective produced water

management is critical to the sustained

development of shale gas by high

‐ volume

hydraulic fracturing, particularly in

Pennsylvania, where deep

‐ well injection

capacity for produced water disposal is

almost nonexistent. During 2012, in the

Pennsylvania Marcellus, operators drilled

about 1,365 horizontal wells and completed

about 540 horizontal wells, generating over

27 MM bbl of produced water

(Pennsylvania Department of

Environmental Protection, 2013) 1,2,3

. This

produced water must be disposed of by

deep

‐ well injection, reused as blendstock in

subsequent hydrofracturing jobs, or

thermally recovered as distilled water and

an optional salt product. As of 2011,

produced water disposal in POTWs 4 is no

longer an option 5

. Since 2010, the

produced water volume from Pennsylvania

Marcellus horizontal wells has increased

dramatically, as shown in Figure 1. During

this period, 83

‐ 89% of produced water was

disposed of by blending with fresh water for

reuse in hydraulic fracturing; the balance

was disposed of by deep

‐ well injection

(UIC 6 ). However, disposal of such a large

percentage of produced water by reuse in

hydrofracturing is not sustainable. Hayes

showed through a modeling study that for a

given county

‐ size shale gas development

area, as more wells are completed

(generating more produced water), and the

rate of new completions peaks and begins

to decline (requiring less produced water

for blendstock), the supply of produced

water overtakes the demand for produced

water (Hayes, 2012). Excess produced

water must be either deep

‐ well injected or

recovered via treatment. Figure 1. Pennsylvania Marcellus

Horizontal Well Produced Water Volume

0 5 10 15 20 25 30

2008 2009 2010 2011 2012 Produced (total)

Reuse (hydrofracturing)

Deep-well InjectionMM bbl Water

The cost to truck water from eastern

Pennsylvania into Ohio and disposal by

deep

‐ well injection is generally in excess of

$12 per barrel. Thermal processes for

produced water recovery by evaporation

only and by both evaporation and NaCl

crystallization are very cost competitive

with these transportation and deep

‐ well

injection costs (Tinto & Solomon, 2010).

For a design case produced water

composition (“Design Case

‐ 1”, or “DC

‐ 1”,

described below in Table 1), about 55% of

the water is recoverable as distilled water

by evaporation only. The resulting brine

concentrate may be disposed of by deep

‐

well injection or it may be sent to a central

facility for further water and salt recovery.

Alternatively, it may be sold for uses such as

well kill fluid. The pretreatment

requirements for this process—lime or

caustic treatment to remove iron,

manganese, and suspended solids—are

relatively straightforward and have been

described earlier (Silva, Matis, Kostedt, &

Watkins, 2012).IWC

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3 For a design case produced water

composition, about 85% water recovery is

feasible by evaporation and NaCl

crystallization. The NaCl product may either

be disposed of as nonhazardous waste in a

RCRA

‐ D landfill 7

, or it may be beneficially

reused as, for example, road deicing salt or

feedstock to a chlor

‐ alkali plant. Because of

the presence of both barium and radium in

much of the Marcellus produced water,

additional pretreatment for both barium

and radium removal is needed prior to NaCl

recovery. For RCRA

‐ D disposal in

Pennsylvania, the salt product must pass

TCLP with respect to barium 8 and its 226 Ra

activity must be less than 25 pCi/gm. For

beneficial reuse in Pennsylvania, the salt

product must pass Pennsylvania’s “co

‐ product” specification, which states that “a

proposed co

‐ product [i.e. salt recovered

from produced water] may not present a

greater threat of harm to human health and

the environment than use of an

intentionally manufactured product or

produced raw material (Pennsylvania

Code)”. For example, if the recovered salt is

to be used as road deicing salt, the

recovered salt must have barium and

radium concentrations no higher than rock

salt, which is the raw material produced for

this purpose. Thus, the recovered salt must

have a barium concentration no higher than

that of rock salt, which is about 5 ppm

(Kaufmann, 1960), and a 226 Ra activity no

higher than that of rock salt, which is about

0.02 pCi/gm 9

. The purpose of this paper is

to define produced water barium and

radium pretreatment specifications such

that the recovered NaCl product meets

Pennsylvania’s co

‐ product determination

for rock salt. In an earlier report, a

comparison among seven pretreatment

processes for barium and radium removal from produced water showed sulfate

precipitation to be the most cost

‐ effective

pretreatment process (Silva, Matis, Kostedt,

& Watkins, 2012). For the design case

produced water composition, the cost of

pretreatment chemicals (Na 2 SO 4 ) and

disposal of (Ba,Ra)SO 4 pretreatment sludge

in a NORM 10 disposal facility was in the

range of $1.20

‐ $2.00/bbl feed water,

including the cost of sludge transportation

from central Pennsylvania to Texas (Silva,

Matis, Kostedt, & Watkins, 2012).

MARCELLUS SHALE GAS WATER CHEMISTRY

We defined a design case produced

water composition (Design Case

‐ 1, or DC

‐ 1)

for process analysis based on a previously

reported survey of six Marcellus produced

waters and one Barnett produced water

(Silva J. M., Matis, Kostedt, & Watkins,

2011). For lab pretreatment, evaporation,

and crystallization experiments, we utilized

produced water from the Barnett, which we

spiked with barium to achieve the level in

DC

‐ 1 (6,200 mg/L). We designated this

composition as DC

‐ Expt. Table 1 shows

both compositions.

We obtained nine additional

Pennsylvania Marcellus produced waters

and analyzed these for metals, anions, and

radionuclides using inductively coupled

plasma

‐ optical emission spectroscopy (ICP

‐ OES), ion chromatography (IC), and gamma

spectrometry with a high

‐ purity germanium

detector (HPGe), respectively, in 2013. The

waters came from a broad geographic

region spanning Greene County in

southwest Pennsylvania to Bradford County

in northeast Pennsylvania. We utilized the

median from these samples to establish

Design Case

‐ 2, which is also shown in TableIWC

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4 1

. Although the sample size is too small to

make definitive conclusions regarding

trends in produced water composition, the

2013 produced water samples show

significantly higher TDS levels (median

242,300 mg/L) than the 2011 survey (132,460 mg/L). The Group II metal

concentrations in the 2013 survey were also

generally higher than the 2011 survey.

Figure 2 shows the geographic distribution

of barium and 226 Ra for all 15 Marcellus

produced water samples.

Table 1. Design Case Produced Water Compositions

(all values mg/L, except where noted)

Component 2011 Survey

Design Case

‐ 1 DC

‐ Expt 2013 Marcellus Survey (9 samples)

Minimum Maximum Median (Design Case

‐ 2)

Na 35,000 51,200 31,100 64,400 51,900

Mg 800 1,775 1,010 2,550 1,860

Ca 9,500 18,960 11,100 34,700 25,500

Sr 2,500 1,670 2,630 11,500 6,120

Ba 6,200 6,200 300 28,800 8,200

Mn 5 4 3 24 10

Fe 50 10 42 165 120

Cl 78,407 122,200 77,900 179,000 147,000

TDS 132,460 202,000 124,100 323,800 242,300

226

‐ Ra, pCi/L 5,000 6,900 2,730 17,800 12,500

Figure 2. Produced Water Barium Concentration, mg/L (blue) and 226 Ra Activity, pCi/L (red)

(numbers in parentheses indicate number of samples from specific county)

The highest TDS samples were from

Clearfield County, which had TDS levels of

290,000

‐ 300,000 mg/L. Barium, a

constituent that has important implications

from a salt recovery perspective, ranged in concentration from 300 to 28,800 mg/L and

was generally higher in central and eastern

Pennsylvania. 226 Ra concentrations ranged

from 2,730 to 17,800 pCi/L and in general

followed the trend in bariumIWC

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5 concentrations (increasing from southwest

to northeast Pennsylvania). The radium

concentrations in these samples do not

pose a significant threat due to external

radiation, but safety precautions will need

to be in place for handling treatment

residuals (e.g., pretreatment sludge).

EVAPORATION/CRYSTALLIZATION MODEL

FOR WATER AND SALT RECOVERY

We utilized Aspen PlusTM with the

electrolyte model from OLI Systems, Inc. for

all the calculations in this study. The OLI

electrolyte package has proven to be an

indispensable tool in process evaluation,

particularly for modeling concentrated

electrolyte systems encountered in

produced water recovery (Silva, Matis,

Kostedt, & Watkins, 2012). We modeled

evaporation and crystallization as simple

single stage flashes in series. The Aspen

Plus/OLI calculations are idealizations—

each calculation represents steady

‐ state

operation of a process where all streams

are in thermodynamic equilibrium. The

batch crystallization experiments are

dynamic processes—steady

‐ state is never

achieved. However, because we conducted

each batch evaporation/crystallization

experiment over the course of 1

‐ 3 hours,

which is long compared with the time scales

for crystallization and evaporation, we can

treat each point in time in an experiment as

a pseudo

‐ steady state condition. Figure 3

compares the predicted and measured

solution temperatures in a lab

‐ scale batch

evaporation/crystallization of DC

‐ Expt feed

that was pretreated with lime for iron,

manganese, and suspended solids removal

(no barium or radium was removed in

pretreatment). The x

‐ axis is the

concentration factor 11

. Although the agreement is not perfect, the model

captures the main trends.

Figure 4 shows the model

predictions for water and salt recovery, as

well as the weight fraction solids in the

crystallizer mother liquor, as functions of

the concentration factor. For this feed

composition, NaCl crystallization begins at a

concentration factor of just below 2. The

model predicts that only NaCl precipitates

as long as the concentration factor is below

about 4.8 (80% water and salt recovery).

Above a concentration factor of 4.8 (for DC

‐

Expt feed), the model predicts that BaCl 2

and NaCl co

‐ crystallize. Co

‐ crystallization of

NaCl and BaCl 2 must be avoided. When co

‐ crystallization occurs, barium is distributed

throughout such crystals, and the crystals

cannot be purified by crystal treatment

technologies.

To demonstrate the consequences

of co

‐ precipitation of NaCl and BaCl 2 , we

spiked DC

‐ Expt with BaCl 2 so that the

pretreated feed contained 16,100 mg

Ba/liter (Expt 1). The predicted

concentration factor for coincidental

precipitation of NaCl and BaCl 2 for this case

is 2.7. We loaded the laboratory crystallizer

with pretreated feed, and evaporated water

to a concentration factor of 2.95. The

pretreated produced water, on a dry basis,

contained 80,000 ppm Ba. The dewatered

and dried crystals from the crystallizer

contained 100,000 ppm Ba, which suggests

that BaCl 2 co

‐ crystallized with NaCl. The

Aspen Plus/OLI model correctly predicts

that co

‐ crystallization will occur under the

conditions of this test, but the model does

not predict the crystal morphology. Figure

5 shows SEM micrographs of the NaCl

crystals from this experiment, bothIWC

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6 dewatered and twice treated for crystal

purification. These micrographs suggest

that relatively small (5  ) BaCl 2 crystals grow

on relatively large (50

‐ 125  ) NaCl crystals.

Even after two crystal treatments, the BaCl 2 crystals appear to stick to the NaCl crystals.

No CaCl 2 or SrCl 2 was detected in these

BaCl 2 crystals.

Figure 3. DC

‐ Expt Temperature Profiles

106 107 108 109 110 111 112 113

1 1.5 2 2.5 3 1-liter lab crystallization

Aspen Plus/OLI modelCrystallizer Pot Temperature, C

Concentration factor vs. Pretreated Produced Water DC-Expt Produced Water

1 atm Figure 4. Model Predictions for Water and

Salt Recovery

0 0.2 0.4 0.6 0.8

1

1 2 3 4 5 6 NaCl Recovery

H2O Recovery

BaCl2 Recovery

xW Solids XTL PurgeFraction

Concentration Factor vs. Pretreated Produced Water DC-Expt Produced Water

1 atm

Figure 5. NaCl Crystals from Spiked DC

‐ Expt Pretreated Produced Water (Expt 1).

A: Dewatered Crystals, B: After 2X Purification Treatments

We also conducted a crystallization

test under conditions for which BaCl 2 co

‐ crystallization is not expected. Here, we spiked pretreated DC

‐ Expt produced water

to a level of 6,900 mg Ba/L (Expt 2). The

predicted concentration factor below which

BaCl 2 is not expected to co

‐ precipitate isIWC

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7 5.0. We conducted the crystallization at a

concentration factor of 3.0. Figure 6 shows

images of the untreated NaCl crystals from

this crystallization. The amorphous

material in Figure 6B comprises CaCl 2 , SrCl 2 , and BaCl 2

. Both the composition and the

interstitial position of this amorphous

material suggest that this material

comprises dried crystallizer liquor that was

entrained with the NaCl crystals. The

moisture content in the untreated

dewatered crystals sampled from the

crystallizer was measured to be 15.6 wt%.

Based on this value, the predicted Ba

concentration in the dried crystals is 4,050

ppm. The measured Ba concentration in

the dry crystals was 6,850 ppm, which is

consistent with 24 wt% moisture in the

untreated dewatered crystals. This

discrepancy may be accounted for by moisture evaporation from the dewatered

crystal sample prior to the moisture

measurement by oven drying.

Table 2 shows the mass ratios of

Ba/Sr and Ba/Ca for the crystals and the

evaporator feed for both experiments. For

Expt 1, the mass ratios of both Ba/Sr and

Ba/Ca were about 7.5 times higher for the

crystals than for the feed solution. This

suggests that barium became concentrated

in the salt crystals, which is consistent with

co

‐ precipitation of BaCl 2 and NaCl. In

contrast, for Expt 2, the mass ratios of both

Ba/Sr and Ba/Ca were essentially identical

in both the crystals and in the feed solution.

This suggests that barium on the NaCl

crystals came from entrained crystallizer

concentrate, not co

‐ precipitated BaCl 2

.

Figure 6. NaCl Crystals from Spiked DC

‐ Expt Pretreated Produced Water (6,900 mg Ba/L)

B: Magnified Image of Circled Section in AIWC

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8 Table 2. Crystal and Evaporator Feed Solution Mass Ratios

Ratio (evap feed) Ratio (crystals) 

##  

  ratio crystals

ratio evap feed

Expt 1

Ba/Sr 11 83 7.5

Ba/Ca 0.80 5.9 7.4

Expt 2

Ba/Sr 4.5 4.6 1.0

Ba/Ca 0.34 0.34 1.0

INTEGRATED PROCESS MODEL

Lime/NaOH treatment is an effective

treatment for iron, manganese, and

suspended solids removal from produced

water. Based on a comparison reported

earlier among pretreatment techniques for

barium and radium removal from produced

water, sulfate precipitation was selected as

the most cost

‐ effective method. This

section utilizes an Aspen Plus/OLI

simulation model to develop a relationship

between the barium concentration in the

pretreated water and the barium content in

the dried salt product. Based on this

relationship and a given barium

specification for the product salt, the

pretreatment barium target for the

produced water may be established.

Because the chemical behavior of

radium and barium are virtually identical,

and because the concentration of radium in

produced water is about nine orders of

magnitude less than that of barium

, radium

is not included in the Aspen Plus/OLI model.

Doener and Hoskins demonstrated that

when contacted with sulfate ion, barium and radium precipitate as a solid solution

(Ba,Ra)SO 4 that has the same ratio of

radium to barium as was present in the

original solution, which leaves the ratio of

radium to barium in the treated solution

unchanged (Doener & Hoskins, 1925). We

saw the same effects when we introduced

Na 2 SO 4 into Marcellus produced water

samples in lab

‐ scale experiments. Based

on these results, we assume that all streams

in the produced water recovery process

(except for the distilled water product) have

the same ratio of radium activity to barium

concentration, and that this ratio is equal to

that measured in the raw produced water

feed. For DC

‐ 1, the ratio is 0.81 pCi

226 Ra/mg Ba.

Figure 7 shows a process flow

diagram for the integrated process:

produced water pretreatment, evaporation,

crystallization, dewatering, and two stages

of crystal treatment. Table 3 shows values

for key operating variables. Operating

metrics, such as the barium concentration

in the crystallizer product, are calculated

from the Aspen Plus stream report in a

separate spreadsheet.IWC

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9 Figure 7. Process Flow Diagram for Produced Water Pretreatment and Recovery

Table 3. Key Operating Parameters for Aspen Plus/OLI Process Simulation

Unit Operation Parameter Typical Values

Evaporation/Crystallization Pressure 1 atm

Water Recovery in evaporator/crystallizer 0.85

Crystal Treatment Wt fraction moisture in dewatered crystals 0.03

‐ 0.05 a

Crystal treatment liquor/crystal mass ratio 0.02

‐ 0.2 b

a (Kirk

‐ Othmer Encyclopedia of Chemical Technology, 2004)

b (Ullman's Encyclopedia of Industrial Chemistry, 2007)

PRETREATMENT TARGETS FOR SALT

RECOVERY

Using the Aspen Plus/OLI process

model, with operating values selected from

the ranges shown in Table 3, we calculated

the composition of the wet crystals leaving

the dewatering device and each treatment

stage for Design Case

‐ 1 feed composition

(DC

‐ 1). For simplicity, rather than including

the actual pretreatment steps in these

calculations, we conducted a series of

calculations for DC

‐ 1 produced water, from

which Fe, Mn, suspended solids and a

variable amount of Ba had been removed.

Table 4 shows the pretreated produced

water compositions for DC

‐ 1, including the

range of barium concentrations. For these

calculations, it is assumed that all Group II metals in the pretreated produced water

exist as chlorides.

Table 4. Pretreated Produced Water Feed

Composition (mg/L)

Component DC

‐ 1 Pretreated

Na 34,800

Mg 800

Ca 9,450

Sr 2,490

Ba 0

‐ 6,160

Cl 77,840

TDS 131,500

Figure 8 shows the results of these

calculations. For DC

‐ 1 from which no

barium has been removed during

pretreatment (i.e., the evaporator feed

contains 6,160 mg Ba/L), the dewateredIWC

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10 crystals contain about 1,400 ppm Ba vs. dry

NaCl crystals. Crystals leaving crystal

treatment stage

‐ 1 contain about 550 ppm

Ba, and crystals leaving the crystal

treatment stage

‐ 2 contain about 160 ppm

Ba. These calculations suggest that starting

with DC

‐ 1 feed (with 6,160 mg/L Ba), for

salt that is to be disposed of in a RCRA

‐ D

landfill, dewatering alone yields NaCl

crystals that will pass TCLP with respect to

barium, with a modest safety margin. As

discussed above, the radium activity in the

salt product is expected to be proportional

to the barium concentration. The

estimated 226 Ra activity in the dry,

dewatered NaCl crystals is 1.4 pCi/gm 12

, which is well below Pennsylvania’s

regulatory limit of 25 pCi/gm for

nonhazardous waste disposal.

Figure 9 shows the same

calculations, but is focused on the low

range of barium concentrations required for

beneficial reuse of the NaCl product.

Assuming the target concentration for

barium in the crystal treatment stage

‐ 2

crystals is 5 ppm, the pretreated produced

water entering the evaporator needs to be

below about 200 mg/L. Pretreatment of

DC

‐ 1 produced water to a barium

concentration of 100 mg/L by sulfate

treatment would enable a safety margin

with respect to barium in the final salt

product. Figure 8. Residual Barium in Treated NaCl

Crystals (full range)

0 500 1000 1500

0 1000 2000 3000 4000 5000 6000 7000 Dewatered Crystals

After Treatment-1

After Treatment-2[Ba] in Dry NaCl Crystals (ppm, wt/wt)

[Ba] in Pretreated Feed (mg/L)

Figure 9. Residual Barium in Treated NaCl

Crystals (low range)

0 10 20 30 40 50

0 50 100 150 200 Dewatered Crystals

After Treatment-1

After Treatment-2[Ba] in Dry NaCl Crystals (ppm, wt/wt)

[Ba] in Pretreated Feed (mg/L)

The estimated 226 Ra activity in DC

‐ 1

produced water that has been sulfate

treated to reduce the Ba concentration to

100 mg/L is about 80 pCi/L. The estimated

226 Ra activity in the crystal treatment stage

‐

2 crystals for this pretreated water is aboutIWC

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11 0.002 pCi/gm, which is an order of

magnitude lower than typical values for

rock salt.

As shown earlier the sulfate sludge

resulting from pretreating DC

‐ 1 produced

water contains about 200 pCi 226 Ra/gm wet

solids (45 wt% solids) (Silva, Matis, Kostedt,

& Watkins, 2012). This material needs to be

disposed of in a NORM disposal facility (e.g.,

Newpark Resources or Lotus LLC).

SUMMARY AND CONCLUSIONS

Produced water reuse is currently a

very effective method for disposal in the

Marcellus shale gas play. However, as the

Marcellus continues to be developed, the

supply of produced water is expected to

exceed the demand for blendstock for well

completions. For sustained development of

the Marcellus, economical water and salt

recovery options are needed. Much of the

produced water in the Pennsylvania

Marcellus contains elevated levels of

barium and NORM ( 226 Ra). For high levels

of distilled water recovery from produced

water (e.g. 85%), NaCl is crystallized as a

byproduct. For the NaCl product to be

disposed of as nonhazardous waste, it must

pass TCLP with respect to barium and

contain no more than 25 pCi/gm of 226 Ra

(latter specification is for Pennsylvania;

varies by state). For this NaCl to be used for

a beneficial purpose in Pennsylvania (e.g.,

road deicing), it must contain no higher

levels of contaminants than products

currently in use for the same purpose (e.g.,

rock salt). Typical concentrations of Ba and

226 Ra in rock salt are 5 ppm and 0.02

pCi/gm, respectively. We developed an Aspen Plus/OLI

process model to estimate the barium

concentration and 226 Ra activity in a dry salt

product from a water and salt recovery

process. For salt product disposal as

nonhazardous solid waste, Design Case

‐ 1

produced water, which contains about

6,200 mg/L barium and 5,000 pCi/L 226 Ra,

needs no pretreatment for barium or

radium removal, as long as the NaCl crystals

leaving the crystallizer are dewatered to

about 3 wt% moisture. On the other hand,

for the salt product to be used as road

deicing salt in Pennsylvania, Design Case

‐ 1

produced water needs to be pretreated to

about 200 mg/L barium, and the dewatered

crystals must be further treated in order for

the dry salt product to contain less than 5

ppm barium. To have a 2X safety margin,

the produced water needs to be pretreated

to about 100 mg/L barium prior to

evaporation. The resulting salt product

226 Ra activity is estimated to be about an

order of magnitude lower than that of

typical rock salt.

ACKNOWLEDGMENTS

Funding for this project is provided

by RPSEA through the “Ultra

‐ Deepwater

and Unconventional Natural Gas and Other

Petroleum Resources” program authorized

by the U.S. Energy Policy Act of 2005.

RPSEA ( www.rpsea.org ) is a nonprofit

corporation whose mission is to provide a

stewardship role in ensuring the focused

research, development and deployment of

safe and environmentally responsible

technology that can effectively deliver

hydrocarbons from domestic resources to

the citizens of the United States. RPSEA,

operating as a consortium of premier U.S.

energy research universities, industry, andIWC

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12 independent research organizations,

manages the program under a contract with

the U.S. Department of Energy’s National

Energy Technology Laboratory.

The authors would also like to thank

Joe Tinto and Bruce Bishkin, both of GE

Power and Water Systems, Bellevue, WA,

for many helpful discussions.

NOTES

1 For this paper, both flowback and produced

water are referred to as produced water.

2 Well drilling, completions, and produced water

estimates based on Pennsylvania Department

of Environmental Protection oil and gas web

site.

3 To put this disposal problem in perspective,

assuming a mean total dissolved solids (TDS)

level of 10 wt% for Pennsylvania Marcellus

produced water, the amount of solids (mostly

NaCl) in the produced water in 2012 was about

480,000 metric tons, which may be compared

with a total U.S. annual NaCl usage for road salt

of about 20 MM metric tons.

4 POTW: Publically Owned Treatment Works

(water treatment plants)

5 In 2011, the Secretary of the Pennsylvania

Department of Environmental Protection,

Michael Krancer, on behalf of the Governor,

requested all exploration and production

companies and drilling companies to voluntarily

cease disposing of flowback and produced

water in POTW’s. This was a request, not a

regulatory action, and it was complied with

100%.

6 Deep

‐ well injection is also referred to as UIC

(underground injection control).

7 RCRA

‐ D Landfill: nonhazardous waste landfill

8 TCLP: Toxicity Characteristic Leaching Protocol.

1 gm solid is extracted with 20 gm dilute acetic

acid. The extract must contain less than 100 mg

Ba/liter, which corresponds to 2100 ppm by

weight extractable Ba in the original dry salt. 9 Measured at GE Global Research Center

10 NORM: Naturally Occurring Radioactive

Material. For shale gas produced water, the

NORM element of interest is radium

‐ 226

( 226 Ra).

11 Concentration factor: (volume solution in

evaporator

‐ crystallizer)/(volume initial solution)

12 The estimated 226 Ra activities for treated

crystals are 0.5 pCi/gm (after crystal treatment

stage

‐ 1) and 0.2 pCi/gm (after crystal treatment

stage

‐ 2).

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‐ Othmer Encyclopedia of Chemical

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Pennsylvania Code, Fry Communications,

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