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Deep Well Injection for Deep Well Injection for Concentrate Disposal Concentrate Disposal

Robert G. Maliva, Ph.D., P.G.Robert G. Maliva, Ph.D., P.G.

RO Roundtable MeetingRO Roundtable Meeting

February 7, 2006February 7, 2006

Why use injection wells for concentrate Why use injection wells for concentrate disposal?disposal?

Often more costOften more cost--effective than other disposal effective than other disposal options.options.Permanent removal of concentrate from the Permanent removal of concentrate from the environment. environment. Minimal surface footprint.Minimal surface footprint.Aesthetically not objectionableAesthetically not objectionableMay be the only viable option for regulatory or May be the only viable option for regulatory or technical reasons.technical reasons.Operationally simple.Operationally simple.

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Injection well designInjection well design0

500

1,000

1,500

2,000

2,500

3,000

DEP

TH (f

t bls

)

Deep injection well negativesDeep injection well negatives

Expensive ($1,000,000s).Expensive ($1,000,000s).Risk Risk –– no guarantee that system will no guarantee that system will satisfactorily perform, particularly in areas satisfactorily perform, particularly in areas without deep injection well history.without deep injection well history.Public (environmental advocacy group) Public (environmental advocacy group) objections.objections.Tightly regulated. Tightly regulated.

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Injection well regulationsInjection well regulations

Safe Drinking Water Act (1974) requires USEPA Safe Drinking Water Act (1974) requires USEPA to establish a system for the regulation of to establish a system for the regulation of injection activities.injection activities.USEPA Underground Injection Control (UIC) USEPA Underground Injection Control (UIC) Program.Program.States can apply for primary enforcement States can apply for primary enforcement authority (primacy).authority (primacy).Primacy states follow USEPA rules and can add Primacy states follow USEPA rules and can add additional state regulatory requirements.additional state regulatory requirements.

Goal of Federal UIC regulationsGoal of Federal UIC regulations

Prevent endangerment of Underground Sources Prevent endangerment of Underground Sources of Drinking Water (of Drinking Water (USDWsUSDWs).).USDW USDW -- aquifer containing < 10,000 mg/L of aquifer containing < 10,000 mg/L of total dissolved solids.total dissolved solids.Endangerment Endangerment –– result in the presence of any result in the presence of any contaminant, such that it results in noncontaminant, such that it results in non--compliance with any national primary drinking compliance with any national primary drinking water regulation. water regulation. Endangerment concerns do not apply to nonEndangerment concerns do not apply to non--USDW aquifers (> 10,000 mg/L) USDW aquifers (> 10,000 mg/L)

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Types of injection wells used for Types of injection wells used for concentrate disposalconcentrate disposal

Class I Class I –– inject waste below the lowermost inject waste below the lowermost formation containing a USDW within one formation containing a USDW within one quarter mile of a quarter mile of a wellborewellbore..Class V Class V –– well other than a Class I well. May well other than a Class I well. May inject into or above a USDW.inject into or above a USDW.Key point Key point –– in Class V wells in Class V wells injectateinjectate(concentrate) must meet applicable (concentrate) must meet applicable groundwater standards (i.e., no endangerment groundwater standards (i.e., no endangerment of a USDW).of a USDW).

Basis technical requirements for Basis technical requirements for permitting new injection wells systemspermitting new injection wells systems

Mechanical integrity testing requirements. Well Mechanical integrity testing requirements. Well muse be constructed so that it does not leak or muse be constructed so that it does not leak or there is no migration behind casing.there is no migration behind casing.

Area of review requirements. Provide evidence Area of review requirements. Provide evidence for absence of vertical migration avenues from for absence of vertical migration avenues from injection zone.injection zone.

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UIC Permitting InformationUIC Permitting Information

Geological/Geological/hydrogeologicalhydrogeological investigation.investigation.Structural integrity of the well (design Structural integrity of the well (design information and proposed testing program).information and proposed testing program).Proposed operational information.Proposed operational information.Area of review investigation & corrective Area of review investigation & corrective actions.actions.Proposed monitoring plansProposed monitoring plans

Hydrogeologic issuesHydrogeologic issues

Deep injection wells are not a viable option Deep injection wells are not a viable option everywhere as hydrogeology may be everywhere as hydrogeology may be unfavorable.unfavorable.

Basis hydrogeologic requirements for Class I Basis hydrogeologic requirements for Class I Injection wells:Injection wells:An aquifer below the deepest USDW with a An aquifer below the deepest USDW with a transmissivity sufficient to efficiently accept transmissivity sufficient to efficiently accept design concentrate flow.design concentrate flow.Effective confinement between injection zone Effective confinement between injection zone and bottom the deepest and bottom the deepest USDWsUSDWs..

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‘‘Boulder ZoneBoulder Zone’’, South Florida, South Florida

USDW

USDW

Injection zone

Injection well

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Water Quality IssuesWater Quality Issues

CorrosivityCorrosivity: Injected fluids should not : Injected fluids should not adversely impact injection well mechanical adversely impact injection well mechanical integrity.integrity.Scaling: Minimize precipitation of minerals Scaling: Minimize precipitation of minerals within casing and formation.within casing and formation.Other adverse fluidOther adverse fluid--rock interactions (e.g., rock interactions (e.g., clay minerals and clay minerals and redoxredox reactions) that could reactions) that could clog pores. clog pores.

Water Quality Issues: ScalingWater Quality Issues: Scaling

Groundwater typically is in approximate Groundwater typically is in approximate chemical equilibrium with aquifer rock.chemical equilibrium with aquifer rock.Concentrate has a tendency to be Concentrate has a tendency to be supersaturated with some minerals (e.g., supersaturated with some minerals (e.g., calcite, barite, quartz).calcite, barite, quartz).Saturation state can be evaluated using Saturation state can be evaluated using geochemical speciation/mineral saturation geochemical speciation/mineral saturation programs (e.g., PHREEQC).programs (e.g., PHREEQC).BenchBench--top top experiments.experiments.Need to look at fluidNeed to look at fluid--rock interaction under rock interaction under injection zone rather surface conditions. injection zone rather surface conditions.

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Water Quality Issues: KineticsWater Quality Issues: Kinetics

Kinetics Kinetics –– study of reaction rates.study of reaction rates.Chemical reactions may be Chemical reactions may be thermodynamically favorable but occur at thermodynamically favorable but occur at too slow a rate to impact injection well too slow a rate to impact injection well systems (e.g., quartz precipitation).systems (e.g., quartz precipitation).

PretreatmentPretreatment

Prevent precipitation of minerals within casing of Prevent precipitation of minerals within casing of formation, particularly near borehole.formation, particularly near borehole.Strategy used is very system specific.Strategy used is very system specific.Adjust chemistry so Adjust chemistry so injectateinjectate no longer saturated with no longer saturated with respect to mineral in question (e., pH adjustment to respect to mineral in question (e., pH adjustment to prevent carbonate mineral precipitation).prevent carbonate mineral precipitation).Crystallization inhibitors.Crystallization inhibitors.Pretreatment may not be need if precipitation is very Pretreatment may not be need if precipitation is very slow (kinetics). slow (kinetics).

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Injection Well System Costs: CapitalInjection Well System Costs: Capital

Main cost items are the injection well, associated Main cost items are the injection well, associated monitor monitor well(swell(s), wellhead, ), wellhead, hydropneumatichydropneumatic systems, systems, and instrumentation.and instrumentation.Costs vary greatly depending upon diameter and Costs vary greatly depending upon diameter and depth of well, local driller market, and testing depth of well, local driller market, and testing requirements.requirements.Clewiston, Florida injection well systemClewiston, Florida injection well system

-- $4,900,000 bid price (12/2005)$4,900,000 bid price (12/2005)-- One injection well & one dualOne injection well & one dual--zone monitor wellzone monitor well-- 4.05 MGD design capacity4.05 MGD design capacity-- 10.7210.72”” I.D. fiberglass tubing to 2,900 ft.I.D. fiberglass tubing to 2,900 ft.-- To be completed with open hole to 3,400 ft.To be completed with open hole to 3,400 ft.

Injection Well System Costs: CapitalInjection Well System Costs: Capital

BackBack--up capacity. May need to have 100% redundant up capacity. May need to have 100% redundant injection well capacity if there is no alternative injection well capacity if there is no alternative disposal method (disposal method (≈≈ double costs)double costs)Should design injection well system for maximum Should design injection well system for maximum conceivable capacity, as it may be much less conceivable capacity, as it may be much less expensive to construct a larger well than an additional expensive to construct a larger well than an additional well. well.

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Operational RequirementsOperational Requirements

Continuous monitoring of injection pressure, flow Continuous monitoring of injection pressure, flow rate, volume, and annulus pressure.rate, volume, and annulus pressure.Monitoring of Monitoring of injectateinjectate chemistry.chemistry.Specific Specific injectivityinjectivity and pressure falland pressure fall--off testing.off testing.Monitoring of water quality in monitoring zones.Monitoring of water quality in monitoring zones.Monitoring of water levels in monitoring zones.Monitoring of water levels in monitoring zones.Mechanical integrity test (every 5 years). Mechanical integrity test (every 5 years).

Estimated annual cost $40,000 to $100,000, not Estimated annual cost $40,000 to $100,000, not including labor, electrical, and preincluding labor, electrical, and pre--treatment.treatment.

El Paso Joint Desalination Facility Design InformationEl Paso Joint Desalination Facility Design Information

Source wells: 18 mgdSource wells: 18 mgdRO production: 15 MGDRO production: 15 MGDBlended with 12.5 MGD of high TDS Blended with 12.5 MGD of high TDS groundwatergroundwaterTotal blended supply to distribution: 27.5 MGD Total blended supply to distribution: 27.5 MGD 82.5% design recovery82.5% design recoveryPilot studies have shown potential for 90% Pilot studies have shown potential for 90% recoveryrecoveryConcentrate production 1.8 Concentrate production 1.8 –– 3.2 MGD 3.2 MGD depending on recoverydepending on recovery

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Concentrate Disposal Alternatives Are LimitedConcentrate Disposal Alternatives Are Limited

Evaporative disposalEvaporative disposal-- PassivePassive-- EnhancedEnhancedDeep well injectionDeep well injectionMechanical evaporation/crystallizationMechanical evaporation/crystallizationLime softening to reduce concentrate volumeLime softening to reduce concentrate volume

Injection Well Northeast AreaInjection Well Northeast Area

Target zone salinity Target zone salinity –– 6,500 6,500 ppmppmTransmissivity up to 300,000 Transmissivity up to 300,000 gpdgpd/ft/ftEstimated travel Estimated travel –– 4,100 ft after 30 years4,100 ft after 30 years100100’’s of feet of shale overlaying injection s of feet of shale overlaying injection zone will prevent upward migration of zone will prevent upward migration of injection waterinjection water

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View of Proposed Injection SiteView of Proposed Injection Site

Projected Costs for Deep Well DisposalProjected Costs for Deep Well Disposal

Three wells constructed to Class I standardsThree wells constructed to Class I standardsDepth Depth –– approximately 4,300 ftapproximately 4,300 ftCapital cost Capital cost –– $6.5M$6.5MAnnual operating cost Annual operating cost –– $0.75M$0.75MPresent worth Present worth –– $24.5M$24.5M

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Class I Class I Injection WellInjection Well

Fusselman Dolomite

Evaporites

Hueco Bolson

Undefined Silurian/Ordovician Sediments

Conductor Casing

Injection Casing

Surface Casing

InjectionTubing

Injection Packer

Final Hole

Deep Well Injection is Most Cost EffectiveDeep Well Injection is Most Cost Effective

$24.5M$24.5M$0.75M/ yr$0.75M/ yr$6.5M$6.5MDeep Well Deep Well InjectionInjection

$88M$88M$2.9M/ yr$2.9M/ yr$22.5M$22.5MEnhanced Enhanced EvaporationEvaporation

$71M$71M$0.995M/ yr$0.995M/ yr$41M$41MPassive Passive EvaporationEvaporation

Present Present WorthWorth

Annual Annual O&M CostO&M Cost

Capital Capital CostCost

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Concentrate Water QualityConcentrate Water Quality

Calcite Saturation Index (SI) 0.5 to 1.2Calcite Saturation Index (SI) 0.5 to 1.2Barite SI: 0.9 to 1.0Barite SI: 0.9 to 1.0SiSi: 150 mg/L to 200 mg/L: 150 mg/L to 200 mg/LpH: around 7.4 to 7.8pH: around 7.4 to 7.8Pilot testing completed at UTEP to Pilot testing completed at UTEP to determine precipitation potentialdetermine precipitation potential

Denver Injection Well IssuesDenver Injection Well IssuesUncertaintiesUncertainties::

–– Rocky Mountain Arsenal seismic issues (technical and Rocky Mountain Arsenal seismic issues (technical and perceived). perceived).

Injection of Injection of ≈≈ 165 MG from 1962165 MG from 1962--1966 triggered seismic 1966 triggered seismic activity; what would ECCV 1 to 4 MGD do?activity; what would ECCV 1 to 4 MGD do?

Permitting challenges.Permitting challenges.

Likely public (environmental advocacy group) Likely public (environmental advocacy group) opposition.opposition.

Any induced seismic activity might force abandonment Any induced seismic activity might force abandonment of system after capital investment.of system after capital investment.

–– Uncertainties over hydrogeology of Injection zone Uncertainties over hydrogeology of Injection zone (transmissivity & water quality).(transmissivity & water quality).

–– Oil wells could necessitate corrective actions.Oil wells could necessitate corrective actions.

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Denver Area Injection Well IssuesDenver Area Injection Well IssuesOil and Gas Well OptionsOil and Gas Well Options::

–– Use existing, abandoned, and/or plugged oil and gas Use existing, abandoned, and/or plugged oil and gas wells for disposal of waste concentrates.wells for disposal of waste concentrates.

–– Regulatory Issue: Would the USEPA allow an existing Regulatory Issue: Would the USEPA allow an existing oil and gas well, constructed outside of the UIC oil and gas well, constructed outside of the UIC program and to different standards, to be used for program and to different standards, to be used for industrial waste disposal?industrial waste disposal?

–– Regulatory Issue: Water quality in proposed injection Regulatory Issue: Water quality in proposed injection zone and permitting implications (Class I vs. Class V).zone and permitting implications (Class I vs. Class V).

–– Capacity issue: oil and gas wells are typically not Capacity issue: oil and gas wells are typically not designed for high capacities. There is a big difference designed for high capacities. There is a big difference between producing 100 barrels per day vs. injecting 1 between producing 100 barrels per day vs. injecting 1 MGD.MGD.

ConclusionsConclusionsWhere the hydrogeology is favorable, deep Where the hydrogeology is favorable, deep injection well systems are a very attractive injection well systems are a very attractive means of concentrate disposal, in terms of means of concentrate disposal, in terms of costs (capital and operational), costs (capital and operational), environmental and aesthetic impacts, and environmental and aesthetic impacts, and space requirements.space requirements.Requires some sophistication on the part of Requires some sophistication on the part of operators because of regulatory operators because of regulatory requirements.requirements.Risk element where there is no injection well Risk element where there is no injection well experience and limited experience and limited hydrogeologicalhydrogeological data data –– no guarantee system will meet no guarantee system will meet performance expectations.performance expectations.