# 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! proppant Nbased!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 Odegaard H156H95H 2116H1 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 Mg 2+ (mg/l) 1,444.00 2.40 Ca 2+ (mg/l) 9,862.00 12.00 Sr 2+ (mg/l) 56.00 1.00 Ba 2+ (mg/l) 17.00 0.10 Fe 2+ (mg/l) 205.00 0.20 Zn 2+ (mg/l) 1.20 Pb 2+ (mg/l) 1.90 Cl - (mg/l) 174,561.00 4,220.00 SO 4 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!