# Use	of	High-Voltage	Plasma	Discharges for	the	Treatment	of	Frac/Produced	Water

Young	Cho,	Professor Department	of	Mechanical	Eng.	and	Mechanics (Drexel	Plasma	InsFtute) Drexel	University,	Philadelphia,	PA

Nov.	19,	2014 Shale	Play	Water	Management	2014 Dallas,	TX

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# Table	of	Contents

• What	is	plasma?

• How	to	generate	plasma	in	produced	water?

• What	are	the	goals	of	plasma	treatment?

• Spark	discharge	for	produced	water	treatment

• ValidaFon	tests?

• What	is	the	cost	of	plasma	treatment?

• How	to	implement?

2 /43Pulsed	Corona	in	water Spark	Discharge	in	water

Gliding	Arc	Discharge with	Water	Spray Spark	Discharge	in	water 

# Plasma	Discharges	in	Water	at	Drexel	University

Plasma	Arrays	in	water

Pinhole	Discharge	in	water
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# Products	of	Plasma	Discharge	in	Water

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## Acidity H + 

## and NO x 

## ReacFve	Species O,	OH,	HO 2 

## ,	etc. UV	RadiaFon

High	Temp Over	2000K

Shock	Waves Electric	Field CavitaFon

# Book:	Plasma	Discharge	in	Liquid

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# Goals	of	Produced	Water	Treatment

• DisinfecFon

• Sobening:	prevenFon	of	mineral	fouling

• Suspended	solid	removal

• De-oiling:	removing	dispersed	oil	and	grease

• Dissolved	gas	removal:	light	hydrocarbon

• Soluble	organics	removal

• DesalinaFon

Ahmadun ,	F.-R.,	et	al.,	Journal	of	hazardous	materials,	2009. 170 (2-3):	p.	530-551. 6 /43

# ConvenFonal	Methods

• Physical:	filtraFon,	ion	exchange,	RO

• DisinfecFon:	UV,	biocides,	ozone

• Biological	treatment	including	MBR

• Water	sobening	with	chemicals

• Segling	ponds

• EvaporaFon,	steam	stripping

• Others

Ahmadun ,	F.-R.,	et	al.,	Journal	of	hazardous	materials,	2009. 170 (2-3):	p.	530-551. 7 /43

# ConvenFonal	Methods

Hayes,	T.	and	D.	Arthur. Overview	of	emerging	produced	water	treatment	technologies .	in The	11th	Annual	Interna:onal	Petroleum	Environmental	Conference .	2004.	. 8 /43

# Drexel	Plasma	Research	UFlizes Spark	Discharge

• Short	pulses	of	10-20 μ s

• Energy	efficient

• Powerful	shock	waves

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# Spark	Discharge	in	Produced	Water

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# Spark	Discharges

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# Co-Axial	Electrode	ConfiguraFon

Center	HV	electrode:	O.D.	=	0.625	inches Outer	Ground	electrode:	I.D.	=	1.05	inches

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# How	to	Generate	Spark	Discharge	in	Water? Use	Air	Spark-Gap	Switch	( low-to-mid	conducFvity )

Ch

- 1: Voltage with H.V. probe (x 1000) in air spark Gap HV probe Tektronix P6015A High Voltage Probe 1000X 75MHz Ch

- 2: Voltage with H.V. probe (x 1000) in water Ch

- 3: Current with three attenuators (x 160) and probe (x 10) in Ground; current probe (Model: CM

- 10

- L) 

### Cooling	Water	=	0.2	mS/cm Seawater	=	50	mS/cm Produced	W.=	100-200	mS/cm

/43Ch-1	:	Voltage Ch-3	:	Current Peak	Voltage	=	1.6	V	(per division)	x	1000	(Voltage probe)	=	1,600	V
Peak	Current	=	2.5	A	x	5	(per division)	x	9.2	(agenuator)	x 10	(current	probe)	=	1,150	A

The energy in a spark pulse was calculated by the two different methods: (1) Energy (J per pulse) = 0.5CV 2 = 0.5(8 microF)(3 kV) 2 = 36 J/pulse (2) Energy (J per pulse) from integration method = ! ! ! ! !" = 80 ! / !"#$% The actual value of the spark energy per pulse should be between the two calculated values. 

# Spark:	Voltage	and	Current	Profiles

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# ValidaFon	Tests

/43Tank	A Tank	B 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

/43Tank	A Tank	B 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

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## APB	result Day	14

10^7
10^6
10^5
10^4
10^3
10^2
10^1 Sample
no. Tr 3-3 Tr 3-2 Tr 3-1 Con 3-2 Con 2-1 Flow Rate 5	Gal/min Red	color

Yellow	color 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark (Produced	Water)

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# APB test results showed 2-log reduction after 10 minutes of spark discharge. 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

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## SRB	result -	0	Hour Day	0

Day	1

Day	2

Day	3

Day	4

Control Tr-1 :1	min Tr-2 :3	min Tr-3 :5	min Tr-4 :8	min Tr-5 :10	min Tr-5:	1-log	reducFon 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

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## SRB	result

Day	0

Day	2

Day	3

Con 1-1 Con 1-2 Con 2-2 Con 3-2 Tr 1-1 Tr 1-2 Tr 1-3 Tr 2-1 Tr 2-2 Tr 2-3 Tr 3-1 Tr 3-2 Tr 3-3 1	Gal/min 3	Gal/min 5	Gal/min



## Produced	water	without	diluFon	was	too	dark	for	SRB	test. 

# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

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### 0 1 2 3 4 5

0	(Post FiltraFon) 1 3 5 10Log	reducFon	(cfu/mL)



## Treatment	Time	(min) SRB	0	hr SRB	24	hr APB	0	hr APB	24	hr



## 0 hr means immediate incubation at the completion of plasma treatment, whereas 24 hr means that incubation started 24 h after the completion of plasma treatment.



# DisinfecFon

• 4-log	reducFon	for	SRB	@	10-min	treatment

• 2-log	reducFon	for	APB	@	3-min	treatment

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### 2-log	reducFon	for	SRB 4-log	reducFon	for	SRB

2-log	reducFon	for	APB0 2 4 6 8 10 12

1 3 5Energy	Cost	[kJ/L	per	1-log]

GPM 

### dark,	opaque	water
semi-transparent	water 

# Energy cost (determined through APB reductions)

DisinfecFon	using	Plasma	Spark	Discharge

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# 1. Plasma	DisinfecFon: Once-Through	Flow	with	Spark

UV	is	the	most	useful	in	disinfecFon.
Produced	water	from	shale	gas	(Marcellus): Clear	water à 0.1	kJ/L /one-log	reducFon
Produced	water	from	shale	oil	(Eagle	Ford): Dark	water à 2	kJ/L /one-log	reducFon

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# Energy cost = 4 kJ/L per 2-log Reduction (99%)

@ 500 GPM (12 bbl /min) (= 33 L/s) 4 kJ/L * 33 L/s = 133 kW For 1 hour operation (720 Bbls ), Energy consumed = 133 kW * 1 h = 133 kW.h = $13.00/720 bbl = $0.02/ bbl Sample Calculation: for PW from Shale Oil (Dark)

For produced water from Marcellus: Disinfection energy cost is 20 times less. 25 /43

# 2.	Spark-Assisted	Self-Cleaning	FiltraFon

Co#axial( electrodes( Filter( housing(

Tank(B( Flow( meter(

Pump( Tank(A(

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# 2.	Spark-Assisted	Self-Cleaning	FiltraFon

RecirculaFon	flow	test	was	used	to	monitor	changes	in pressure	drop	across	filter	membrane	over	Fme.

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# 2.	Spark-Assisted	Self-Cleaning	FiltraFon

0 3 6 9 12 15 18 21 24 27 30 33 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 Flow Rate:5 GPM_TDS: 2600 ppm_Pore size: 5 micronP res s ure0D rop0(ps i)

T ime0(min) B a s eline000000000 (No$S park$Dis c harg e) 0S pa rk0dis c ha rge Pumping failed

28 /43Cont rol

- 1

- O ri gi na l f i l t e r c ondi t i on (c l e a n) Cont rol

- 2 : N o s pa rk a t 5 GPM S pa rk t re a t m e nt a t 5 G P M 

# 2.	Spark-Assisted	Self-Cleaning	FiltraFon

29 /430 5 10 15 20 25 30 35 40 45 50 55 60 65 70 )3

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48P res s ure1D rop1(ps i)

T ime1(min) B a s eline111111111 (No$S park$Dis c harg e) 1S pa rk1dis c ha rge PRODUCED WATER_Flow Rate:2 GPM_TDS: 50,000 ppm_Pore size: 5 micron Pumping failed 

# 2.	Spark-Assisted	Self-Cleaning	FiltraFon: Produced	Water

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# 2.	Spark-Assisted	Self-Cleaning	FiltraFon: Produced	Water

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# 3.	Plasma-Assisted	Water	Sobening

Gliding	Arc	with	3	kV, 200	W	power	supply 32 /43

# 3.	Plasma-Assisted	Sobening:	Mechanisms Plasma	discharge	surface	temperature:	2,000	–	4,000	K
High	temperature	plasma d issociates bicarbonate	ions in	water.
Calcium	ions	in	produced	water	can	be	10,000	–	20,000	ppm. Bicarbonate	ions	(max)	is	4,000	ppm	(usually	<	1,000	ppm).

Once,	bicarbonate	ions	in	PW	are	removed,	carbonate	scales cannot	be	formed.	ValidaFon	for	sulfate	salts	is	ongoing.

Note:	H + 

# ions	produced	by	plasma	also	removes	HCO 3 -



# . ) 1 (Re ) ( ) ( ) ( 2 3 

## action g CO aq OH aq HCO + ⇔ − −

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# PrevenFon	of	CaCO 3 

# Fouling	in	HeaFng	Elements With	Plasma	Discharge (with	Ca 2+ 

### =	5,000	ppm)



## CaCO 3 

## scale

No	scale

Wright-Cho DesalinaFon 2014	345	64-71 34 /43

# 3.	Plasma-Assisted	Water	Sobening: What	about	Sulfate	Ions? (e.g.,	mine	water	treatment) Plasma	surface	temperature:	2,000	–	4,000	K
High	temperature	plasma d issociates sulfate	ions in	water.

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# 3.	Plasma-Assisted	Water	Sobening Chemical	Treatment	vs.	Plasma?

Chemicals	are	used	for	water	sobening	such	as:

• Lime,	Ca(OH) 2


# • Soda	ash,	Na 2 

# CO 3


# • CausFc	soda,	NaOH
However,	the	addiFon	of	these	chemicals	increases	the volume	and cost of	sludge	to	be	disposed.
Plasma	water	sobening	removes	bicarbonate	(and	sulfate) ions	to	prevent	mineral	fouling	problems	without increasing	sludge. 36 /43

# 4.	OxidaFon	of	Hydrocarbons	with	Plasma

Produced	Water

Baseline Plasma Treatment
Initial Filtered 30 s 1 min 2 min 3 min 4 min 5 min 7 min 10 min Ba s e l i ne P l a s m a T re a t m e nt 30 s 1 m i n 2 m i n 3 m i n 4 m i n 5 m i n

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# Simultaneous	Hydrocarbon	OxidaFon	and	DisinfecFon with	Plasma Adenosine	triphosphate	(ATP)		Assessments

Control Plasma Treatment Time 30 s 1 min 5 min

Bacteria Assesments ATP (Microbial Equivalents/ mL) 10 7.65 10 7.44 10 7.48 10 5.07

SRB (CFU/mL) 10 4 10 4 10 4 < 10 0 APB (CFU/mL) 10 4 10 4 10 4 10 0 38 /43

# ImplementaFon	of	Plasma	Treatment
Three	key	components	to	generate	plasma	discharge:

• Plasma	Reactor

• Electrodes	(Cathode	and	Anode)

• High	Voltage	Power	Supply

Successful	plasma	treatment	at	5	GPM	and	30	GPM
Current	ongoing	development: Skid	systems	for	100	GPM	(2.5 bbl )	and	500	GPM	(12 bbl )

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# For	2,000	GPM	(50 bbl ), four	12-bbl	modules	can	be	used.

12 bbl Skid

12 bbl Skid

12 bbl Skid

12 bbl Skid Untreated Produced Water Treated Produced Water

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# Skid

Water	Tank Bagery Pump Plasma	Reactor HV	Power	Supply Plasma-treated water 

# ImplementaFon	of	Plasma	Treatment

Once-through	flow	mode	(on-the-fly	system)

Frac	well

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# Treatment	Skid

PW	in	Storage	Pond Pump Plasma	Reactor HV	Power	Supply Plasma-treated	water	return 

# ImplementaFon	of	Plasma	Treatment

RecirculaFng	flow	mode

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# Summary: Plasma	Treatment	can	Perform	MulFple	FuncFons with	Low	Energy	Cost	(~$0.02/ bbl ) 

# 1. DisinfecFon 2. Water	sobening 3. OxidaFon	of	dissolved	hydrocarbons 4. Self-cleaning	filtraFon 5. De-oiling 6. Oxidize	and	precipitate	metal	ions	so	that they	can	be	removed	by	filtraFon Plasma-treated	produced	water	can	be	fed	to	disFllaFon unit	without	mineral	fouling	problem.

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# Acknowledgement

Funded	by	RPSEA	(The	U.S.	Department	of	Energy,	NETL)

Funding	 for	 this	 project	 is	 provided	 by	 RPSEA	 through	 the	 “Ultra-Deepwater	 and UnconvenFonal	Natural	Gas	and	Other	 Petroleum	 Resources”	 program	authorized	 by	 the U.S.	Energy	Policy	Act	of	2005.	 	RPSEA	 ( www.rpsea.org )	is	a	nonprofit	corporaFon	whose mission	is	to	provide	a	stewardship	role	in	ensuring	the	focused	research,	development	and deployment	of	safe	and	environmentally	responsible	technology	that	can	effecFvely	deliver hydrocarbons	 from	 domesFc	 resources	 to	 the	 ciFzens	 of	 the	 United	 States.	 	 RPSEA, operaFng	 as	 a	 consorFum	 of	 premier	 U.S.	 energy	 research	 universiFes,	 industry,	 and independent	research	organizaFons,	manages	the	program	under	a	contract	with	the	U.S. Department	of	Energy’s	NaFonal	Energy	Technology	Laboratory.

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# Thank	you!

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