Analyzing)How)Produced)Water)

Reacts)with)Frac)Fluids)to)Asses)it’s)

Compa=bility)with)the)Fluid)and)

Forma=on

• Assessing)the)compa=bility)of)produced)Dakota)Forma=on)water)with)

gel)fracs)to)ensure)fluid)stability

• Ascertaining)the)scaling)risks)associated)with)Dakota)Forma=on)water)

and)evalua=ng)techniques)for)preven=ng)forma=on)damage

• Discussing)whether)filtra=on)of)Dakota)water)is)necessary)for)frac)fluid)

compa=bility

Michael!McKimmy!–!Hess!Corpora3on!
Dakota!Info!

• Inyan!Kara!Forma3on!is!a!sandy!aquifer!within!

the!Dakota!Group!

• Also!referred!to!as!“Lower!Cretaceous!aquifer”!

• About!5000’!depth!in!Tioga,!ND!region, Current!

supply!well!is!isolated!from!potable!aquifers!with!

9N5/8!casing!cemented!from!4,033’!to!surface!!

• Very!complex!geometry!

• 400N500’!gross!thickness!with!100N300’!net!sand!

generally!

• About!50%!of!sand!is!shaley

Use!of!Dakota!Forma3on!Water!for!Frac

Technical)Challenges)

• Natural!mineral!content!and!

other!chemistry!

– Compatability!with!frac!fluids!

is!difficult!

• Sampling!Issues!

– Where!

– When!

• Drilling!a!new!well!

• Poten3al!Scaling!

Advantages)

• Low!Cost!

• Hess!Operated!

• Elevated!Temp!

• Offsets!potable!water!usage!

• Forma3on!not!used!for!

potable!water;!Current!supply!

well!is!isolated!from!potable!

aquifers!with!9N5/8!casing!

cemented!from!4,033’!to!

surface!!

• Possible!loca3on!in!high!

ac3vity!area!
Ascertaining)the)scaling)risks)associated)with)

Dakota)Forma=on)water)and)evalua=ng)

techniques)for)preven=ng)forma=on)damage
Bakken!Scaling!

• Recent!methods!of!scale!inhibi3on!have!been!

solid!proppantNbased!polymer!scale!inhibitor!or!

phosphonate!based!liquid!scale!inhibitors!

– Hess!and!Basin!Wide!

• Solid!scale!inhibitor!has!been!pumped!on!over!

200!wells!to!date!by!Hess!

– No!Pump!failures!aeributed!to!scale!since!

implementa3on!

• Scale!inhibitor!recommended!in!most!frac

opera3ons!by!Hess!EPT!group!
Bakken!&!Dakota!Water!Analysis!

Component) Concentra=on OdegaardH156H95H2116H1

11/4/2009) )Dakota)

Na+ (mg/l)* 95,592.00 3,755.00 

K+ (if not known =0) (mg/l) 6,272.00 15.00 

Mg2+ (mg/l) 1,444.00 2.40 

Ca2+ (mg/l) 9,862.00 12.00 

Sr2+ (mg/l) 56.00 1.00 

Ba2+ (mg/l) 17.00 0.10 

Fe2+ (mg/l) 205.00 0.20 

Zn2+ (mg/l) 1.20 

Pb2+ (mg/l) 1.90 

Cl- (mg/l) 174,561.00 4,220.00 

SO4

2- (mg/l) 362.00 500.00 

SiO2 (mg/l) SiO2 14.00 

Alkalinity** (mg/l) 426.00 1500 

Calc. Density (STP) (g/ml) 1.178 1.003 

pH, measured (STP) pH 7.19 8.5 
Calcite!Scaling!

0!

100!

200!

300!

400!

500!

600!

700!

800!

900!

Calcite)(mg/L))

Percentage)of)Dakota)Water)

Scaling)Tendency)with)Dakota)Water)

Dakota!water!(Bicarbs!=!1500!

mg/L)!

Dakota!Water!(Bicarbs!=!425!mg/

L)!

Dakota!Water!(Reduced!pH)!
Assessing)the)compa=bility)of)produced)

Dakota)Forma=on)water)with)gel)fracs)to)

ensure)fluid)stability
Water!Quality!

Paramaters)&)Technical)Challenges)

• Bacteria)

– Gel!degrada3on!

– H2S!produc3on!

• Chlorides:)

– Hydra3on!

• pH:))

– Proper!hydra3on!

• Bicarbonates:))

– Affects!buffering!

– Can!interfere!and!delay!Zirc!xl!

fluids!

– Scaling!

• Calcium)&)Magnesium:))

– Scaling!

– Hydra3on!

– Crosslinking!

• Iron:))

– Can!interfere!with!metallic!

crosslinkers

– Over!Crosslinked!fluids!

• Phosphates:))

– Interferes!with!metallic!

crosslinkers

• Sulfates:))

– Can!precipitate!some!crosslinkers
Dakota!vs!Tradi3onal!Sources!

Parameter)

Dakota)Water))

(2wk avg))

Tradi=onal))

(recent)lab)test)) %)Difference)

pH! 8.05! 7.39! 8.9%!

Chlorides!(CI)!N!mg/L! 3842! <28! 13621.4%!

TDS!(ppm)! 13310! 794! 1576.3%!

Sulfates!(SO4)!N!mg/L! 275! 50! 450.0%!

Iron!(Fe)!N!mg/L! 0.245! .181! 35.4%!

Bicarbonates!HCO3)!N!mg/L! 1369! 216! 533.8%!

Calcium!(Ca)!N!mg/L! 43! 196! N78.1%!

Magnesium!(Mg)!N!mg/L! 16! 96! N83.3%!

Phosphates!(PO4)!N!mg/L! 1.08! 0!

Specific!Gravity! 1.008! 1.001! 0.7%!
Bicarbonates!&!Sulfates!

0!

200!

400!

600!

800!

1000!

1200!

1400!

1600!

mg/L)

Date)

Water)Analysis)Over)Time)

Bicarbonates!

Sulfates!

• Bicarbonates:!<500!mg/L!

– Increased!buffer!

concentra3ons!may!be!

necessary!

– Low!pH!zirc!systems!may!

be!more!tolerable!since!

low!pH!buffer!may!

neutralize!Bicarbs

• Sulfates:!<500!mg/L!

– Increased!crosslinker

concentra3ons!may!be!

necessary

Parameter:!Desired!level!
Chlorides!&!TDS!

2000!

4000!

6000!

8000!

10000!

12000!

14000!

mg/L)

Date)

Water)Analysis)vs)Time)

Chlorides!

TDS!

• Chlorides:!<1000!mg/L!

– pH!adjustment!

– Gel!loading!

• TDS!!

– Can!affect!proppant

tracking!QC!if!high!

enough!to!affect!specific!

gravity!

Parameter:!Desired!level!
Iron!&!Phosphates!

0!

0.2!

0.4!

0.6!

0.8!

1!

1.2!

1.4!

1.6!

1.8!

Date)

Water)Analysis)Over)Time)

Iron!

Phosphates!

• Iron:!<10!mg/L!

– Frac!Tanks!are!coated!to!

minimize!rust!

contamina3on!

• Phosphates:!<1!mg/L!

– Increased!crosslinker

concentra3ons!may!be!

necessary!

Parameter:!Desired!level!
Calcium!&!Magnesium!

0!

5!

10!

15!

20!

25!

30!

35!

40!

45!

50!

mg/L)

Date)

Water)Analysis)Over)Time)

Calcium!

Magnesium!

• Calcium!&!Magnesium:!

<400!mg/L!

– Scale!inhibitors!and!fluid!

system!selec3on!to!

prevent!scale!

– pH!adjustment!for!

proper!hydra3on!

Parameter:!Desired!level!
Fluid!Stability:!25!lb/Mgal!High!pH!Borate!
Fluid!Stability:!25!lb/Mgal!High!pH!Borate!
Fluid!Stability:!25N30!lb/Mgal!High!pH!Borate!

Std!Delay!XL!

Lowered!Delay!XL!

Lowered!Delay!XL!&!

caus3c!pH!adjuster!

Lowered!Delay!XL!

Lowered!Delay!XL!
Fluid!Stability:!25!lb/Mgal!High!pH!Borate!
Fluid!Stability!–!Low!pH!Zirconate

S!XL@1

S!XL!@1!

S!XL@0

S!XL!@0!

1.0!!S!XL!

No!S!XL!

50%!Mix;!1.0!S!XL!

50%!Mix;!No!S!XL!
Fluid!Stability!–!Low!pH!Zirconate

Surface!&!Delayed!Xl!

No!Surface!Xl!

Surface!&!Increased!Delayed!xl!

No!Surface!xl/!Increased!Delayed!xl!
Fluid!Stability!–!Low!pH!Zirconate

Surface!and!Delayed!XL! No!Surface!XL!
Fluid!Stability!–!Low!pH!Zirconate
Discussing)whether)filtra=on)of)Dakota)water)is)necessary)for)frac)fluid)

compa=bility
RO!Treatment!of!Dakota!Water!

Parameter) RO)Inlet)) RO)outlet

pH! 8! 7.16!

Chlorides!(CI)!N!mg/L! 6600! 241!

TDS!(ppm)!

Sulfates!(SO4)!N!mg/L! 683.5! 11.09!

Iron!(Fe)!N!mg/L! .132!

Bicarbonates!HCO3)!N!

mg/L! 1920! 90!

Calcium!(Ca)!N!mg/L! 70! 4!

Magnesium!(Mg)!N!

mg/L! 10! 0!

Phosphates!(PO4)!N!

mg/L!

Specific!Gravity! 1.009! .998!
RO!Treatment!of!Dakota!Water!
RO!Treated!Dakota!Water!

25!lb/Mgal!Borate!
Cost!Savings!

Cost)Area) Poten=al)Savings)over)1)year)

Hea3ng!! 4.2!–!8.5!Million!

Water!Material!Costs! ~2.0!Million!

Trucking!Costs! No!Savings!

Based!on!1!yr frac!schedule!and!current!average!costs!
Special!Thanks!

• Leonard!Kalfayan

• Larry!Cenegy!

• Brian!Ward!

• Clyde!Mcafee

• Jeff!Smith!

• Rhee!Halverson!

• Alf!Tischler!

• Kiran Srinivasan

• Claire!hand!