Evaluation of Produced Water Reuse for Hydraulic Fracturing

In Eagle Ford

Atlantic Council Produced Water WorkshopJune 24-25, 2013

Steve Jester, Sr. Principal Environmental Engineer Lower 48 HSE, Houston, TX

Kevin Bjornen, Drilling and Completion Fluid Specialist, Production Technology, Bartlesville, OK

Ramesh Sharma, Staff Process Engineer, Process and Facility Engineering, Houston, TX

ConocoPhillips’ Corporate Water Sustainability Position:

As a responsible global energy company committed to sustainable development, we recognize that fresh water is an essential natural resource for communities, businesses, and ecosystems. Global population growth will increase demand for fresh water and all users – domestic, agriculture, and industry – will need to effectively manage supplies to meet demands.

ConocoPhillips produces and utilizes water in its operations. We are committed to the development of water management practices that conserve and protect fresh water resources and enhance the efficiency of water utilization at our facilities. We will assess, measure, and monitor our fresh water usage and based on these assessments we will manage our consumption and strive to reduce the potential impact to the environment from wastewater disposal.

What is “Freshwater”

Texas Bureau of Economic Geology (BEG)U.S. Geological Survey (USGS)

Fresh Water Utilization

BEG / API

Eagle Ford – 16 Counties in TX- Water Demand Comparison

2008 Water Use Survey Summary Estimates Eagle Ford Counties

Livestock 4%

Drilling & Completions

5.5-6.7%

Irrigation 64%

Steam Electric5%

Mining 3%

Manufacturing 1%

Municipal 17%

540,000 Ac-Ft Total

347,000 ac-ft

29,700 -36,000 ac-ft

Source: TX Water Development Board (http://www.twdb.state.tx.us/wrpi/wus/2008est/2008wus.asp)

Why Look at Produced Water Reuse? – Key Drivers

Part of an overall water management strategyImplementing our company position- how can we use less fresh water?

Optimize our processAlternative Sources:

Brackish/saline water Municipal wastewater Produced water? Where other water sources are scarce or expensive Where ample volumes of PW are available and easy to treat

and transport for reuseAlternative process?

Challenges Using Alternative Water Sources for Hydraulic Fracturing

Transportation and gathering of water (logistics/traffic/envir.)

Treatment of water (cost/lifecycle environmental impact)

Storage of nonfresh water (bacteria/corrosion/environmental)

Blending of water from different sources (produced/fresh)

Consistent and predictable fracturing fluid performance (pre-testing & consistent stream)

Impacts on reservoir and fracture conductivity (rock-fluid interaction & pack damage)

Impacts on short & long term field production (emulsion, scaling, corrosion)

Consistent and predictable fracturing fluid performance

When Does Using Challenged Water Sources Make Sense?

Drivers for Produced or Alternative Water Source

High LowHigh quality source water availability

Produced Water Quality & AvailabilityLow High

Transportation & Logistics

Adds cost Reduces cost

Compatibility w/ fracchemistry

Low High

Compatibility w/ reservoir

HighLow

SWEET SPOT

Landowner Agreements, Regulatory Considerations

Produced Water Quality

Variability is the key term Individual well Well to well Field to field Region to region

Produced water typically has a much higher Total Dissolved Solids (TDS) Suspended Solids Iron Hardness/Scaling potential Boron Oil residue and organic matter

pH

Ferric iron (Fe+3)

Ferrous iron (Fe+2)

Total hardness

Magnesium (Mg+2)

Calcium (Ca+2)

Specific gravity

Chlorides (Cl-)

Carbonate (CO3-2)

Bicarbonate (HCO-3)

Sulfate (SO4-2)

Phosphate (PO4-3)

Silica (SI+4)

Boron (B+3)

Total dissolved solids (TDS)

Total suspended solids (TSS)

Bacteria

Water Quality Impacts on Fracturing Fluids

Total Fe >25 ppmImpacts hydration and thermal stability of polymer.Dilute or dump.

Cl- New CMC systems are intolerant

Interferes with buffers in crosslink systems. Some friction reducers are prone to precipitation.

SO4-2 >200 ppm Interferes with delayed

metallic crosslinkers. High temperature thermal stability also impacted.Precipitate out.

HCO3-1 >600 ppm

Requires pH adjustment for polymer hydration. Impacts Zr crosslinkers (delay and/or stability)

SI-4 Interferes metallic crosslinkers. PO4

-3 ties of metallic crosslinkers. Reduces fluid performance.

Too High > 9.0 poor hydration.

Too Low < 6.0 poor dispersion.

Degradation of Organic PolymersEven after the bacteria have been killed their enzymes are still problematic

B >4 ppm can cause crosslinking in guar gelling agents.

Typical ionic species identified and quantified in source water analysis.

Nearly every produced water will push these limits

Initiatives At ConocoPhillips – Where can we reuse Produced Water?

West Texas Produced water primarily Modest water treatment Low temperature reservoirs (<200°F) Use of large portable storage tanks Feasible w/ scarcity of fresh water in region

Bakken Challenging brine (High TDS and scaling species) Blending with fresh water investigated Challenges with high performance fracturing fluids (>225°F)

High temperature reservoir Scaling potential in water

Eagle Ford Produced water volumes are low (20-30 bbl/day/well) Blending with fresh water investigated Challenges with high performance fracturing fluids (>270°F)

High temperature reservoir Scaling potential in water

Fluid Package Compatibility w/ Produced WaterSlick water and linear gels Salt and hardness tolerant polymers are readily available Possible pH adjustment for hydration Verify compatibility from polymer identification and testing

Guar borate systems Generally adaptable to a variety of water conditions Desirable characteristics (early viscosity, shear recovery) proppant placement Requires high pH (8.5 to +12)

Low temperature (8.5 – 10.0) High temperatures requires higher pH (10 – 12+)

Limited performance above 300°FMetallic crosslink system More potential issues with challenging waters Flexible pH (4 – 11) Must be properly delayed (shear degrading) Balancing delay and early crosslinking/viscosity is difficult

Completion service industry Existing crosslinked packages developed for fresh water Adapting fluids to more challenging conditions Need to develop packages specifically for challenged water

ConocoPhillips High Performance Fracturing Fluid Requirements

Temperature testing (seasonally adjusted) Hydration (70 – 80°F) Wellbore transport (worst case no heat added) Fast temperature ramp (10 – 20 minutes to BHST) Stability for duration of pump time (practical limits)

Shear testing Rheometer geometry (R1B5 or R1B5X) Shear History (representative shear for residence time) Fracture Shear (100 s-1)

Ideal viscosity Slightly building apparent viscosity during high shear period ~100 cp apparent viscosity when entering 100 s-1 period Quick ramp to viscosity peak without thermal thinning period >200 cp apparent viscosity for duration of pump time

Ideal Viscosity Response(High Performance Fluid)

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Eagle Ford Produced Water - Fracturing Fluid Testing

Borate systems employed: Adaptable systemsService Companies adapted formulations Similar performance Some cost Increase possible

Challenges for fluids Naturally occurring boron in water (require low pH during gel hydration, early crosslinking) High temperature challenge +270F (requires high pH for borates) Enough hardness in water – immediate precipitation possible

CaCO3

Mg(OH)2

Viscosity Profiles with 70:30 Source:Produced Water Mix

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Viscosity - 70:30 Mix

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TempThermal

Stability for Pump Time

Early Viscosity & Some Thermal

Thinning

Challenges with High pH Guar Borate Systems – Eagle FordHigh pH to achieve borate cross-linking drives CaCO3, and Mg(OH)2 scale formation No blending

7000 lb solids with P95 fresh water 3000 lb solids with P50 fresh water

90/10 Fresh Water/Produced Water blend 9800 lb solids P95 fresh water case 4900 lb solids P50 fresh water case

250,000 lb of proppant used per stageImpact of calcite solids and other scaling solids on proppant conductivity not well understood Do the these solids flow back due to small micron size?

Calcite solids

Six Inch Pipe – 6 months of operation

Well Prep Frac Operation Plug Mill Out

Tubing Installation

Well TestingProduction

~80-90 K bbls of water per job

Typical Completion Activities – Eagle Ford

95% + water use

Other 5% of water used currently matches produced water volumes where fluids would typically be Slickwater and Linear Gel systems employed in routine well work. Produced water a realistic option here.

Our Approach: Minimal Treatment. Blend PW with Source Water

Goal: TSS and Oil and grease reduction< 1/bbl treatment costEasy operation, smaller foot-print, mobile units available (15 bbl/minute)

Polishing filter

TSS < 20 mg/LpH = 7.5-8.0

TSS ~ 100 mg/LpH = 7.5-8.0

Summary of Eagle Ford PW Reuse ChallengesSmall % well work can be done with filtered produced waterBlending (90/10) source water/produced water for hydraulic fracturing fluid preparation is possible Pre-mature cross linking of high boron content is an issue Higher concentration blends possible where slick water is used Consistent water quality is important

Immediate scaling is an issue with typical source waters with borate systems and is magnified with produced water blends. Significant small fines will be pumped into fracture system Potential negative impact on fracture conductivity? Also true in other high temperature plays where pH needs to by high

(+10)Need to develop frac packages specifically for challenged watersIssues around flow assurance, logistics, and sub-surface rock-water interactions need to be resolved for challenged water sources

Conclusions

Produced Water Reuse is One Option – Subset of Overall Water Management Strategy Optimize Process – 45% reduction Alternative Source – Brackish water 60% PW Reuse - challenging

Reuse of Produced Water – Depends on complex evaluation of Compatibility, Logistics, Reliability, Cost, Environmental ConsiderationsReducing Freshwater Use has been better accomplished via other alternativesNo Single industry-wide “Fit for Purpose” Solution

Questions?

Backup Slides

Water Quality Data Gathering

Well Produced water Saline water(Carrizo)

Fresh Water(Gulf Coast)

Calcium, mg/L 690-2600 10 90.7 (42.2)

Magnesium, mg/L 54-210 Not available 17.7 (10.8)

Boron, mg/L 54-130 < 1 < 1

TDS, mg/L 17000-36000 1200-1600 1722 (763)

Bicarbonate, mg/L 330-1400 720-950 480 (252)

Iron, mg/L 4-98 <8 <8

Sulfate, mg/L 18-160 30 385 (157)

• PW sampling in Jan/Feb 2012• Carrizo data is based on limited sampling• 95th percentile (median) values shown for fresh water

Impact of Water Quality: Scaling Tendency

SI >0 means precipitation can happenSI >2.5 scale inhibitor dosage increases significantlySI>3 scale inhibitor will not be effectiveAll water sources are saturated with respect to calcite

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100% Carrizo 100% Fresh waterP95

100% Fresh waterP50

100% PW P75

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