Applying Membranes to Produced Water Treatment:HIGH RECOVERY REVERSE OSMOSIS TREATMENT PROCESSNovember 2008U.S. Natural Gas Production, Consumption, and Imports1970-2020 (trillion cubic feet)Source: ALL Consulting.Handbook on Coal Bed Methane Produced Water: Management and Beneficial Use Alternatives,July 2003.Major New Sources-CBNG-Tight Sands-ShaleAlong with the gas comes water:typical water production in a CBNG field-20406080100120140160180Jan99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07Jan-08Jan-09Jan-10Jan-11Jan-12Jan-13Jan-14Jan-15Jan-16Jan-17Jan-18Jan-19Jan-20Jan-21Jan-22

Water Production (MBWPD)Along with the water come the water issues...High volumes of produced water that decrease with timeElevated concentrations of dissolved salts (sodiumsalts)Suspended solids from well development and productionwellsLimited disposal optionsIncreased regulationsPressure fromRegulators,Landowners,and PublicAlong with the water issues come regulatory and publicperceptions and concerns:HistoricalProducedWaterManagement:–Deep wellinjection–Directdischarge–Impoundments–Irrigation–TreatmentanddischargeCurrent Trend andFuture ProducedWater Management:–Treatment anddischarge–Managed irrigation–Re-injection tosafe aquifer–Deep wellinjection/storage–Lined stock tanks–“Grandfathered”direct dischargeonlyProduced Water Production Optionsand CostsDirectDischargePassive Treatmentand DischargeIrrigationImpound-mentOffsite Disposal/InjectionRigorousTreatmentCOST ($/per barrel)$0.03-$0.05/bbl$0.04-$0.06/bbl$0.10-$0.16/bbl$0.12-$0.18/bbl$0.25-$2.00/bbl$0.70-$5.50/bblKey Water Management Concerns:Water resource concernsSurface water quality impactsShallow groundwater quality impactsLong-term soil damage from salinity and sodicity (SAR)BOTTOM LINE:Huge CBM resources are driving developmentWater quality concerns driving toward more treatmentWater resource issues handled under water rights laws20,000Produced Water Quality / Basin:Binko, K.L. and Drewes, J.E., 2008, Environmental Engineering Science, Produced Water in the Western USDominant Salts in Produced Water By Basin:Water Treatment Objectives and TechnologiesBasin-Wide Objectives:TDS Removal (soluble sodium salts)Minimize brine disposalMeet stringent discharge criteria for TDS (EC)Cost-effectiveKey Treatment Technologies: Elements of each are neededto meet future objectives!Ion ExchangeReverse OsmosisMechanical EvaporationRO Membrane Separation MechanismConcentratedSaltsFeedFlowH2OH2OH2OH2OMgClFe++HCO3CaSO4Na+++++MembranePressureH2OH2OH2OH2OH2OH2OPermeateSevere fouling results in RO membranes that look like this!RO membranes are designed for a very specificpurpose: to separate dissolved solutes from a solution.RO is a “non-selective” treatment process: all ions arerejected, depending on their mass transport properties.RO concentrates simultaneously as it purifies water.Other constituents of the feed water can interfere withthis separation and make the process inefficient.The deposition of material on the membrane surfacethat impedes the design production and quality of thepermeate has to be avoided.Successful RO systems need effective process step(s)in front of themembrane unit to remove or minimize the presence of constituents in thefeed that can inhibit membrane functionality.Effective pretreatment makes it work by limiting thefouling potential ofthe feed water.What do we need to remember when we have an ROmembrane system?Key to Success: Efficient PretreatmentPretreatment Steps:Particulate removal (coal fines, clay, etc.)Hardness and metals removalBacteria controlOther: Oil and grease, VOC’s, etc.Pretreatment steps allow silicato be concentrated tomuch higher levels without precipitationThe result is an RO process operation at high water recoverywith minimal potential for membrane foulingCDM’s Produced Water Technology SolutionDeveloped over several years in response to industry needEfficient combination of all three key treatment technologies:IX, RO and EvaporationBench and pilot testedCompleted intensive internal technical review processPatent pending process: “Method and Apparatus for theRecovery of Water Containing Silica”How it Works:HighPressure ROEvaporator(Optional)Scale Inhibitor/Dispersant(3-7 ppm)Natural Gas/Waste HeatHCl(intermittent,low volume)DistillatePermPermProducedWaterEffluentDischargeConc Brineor SolidsRejectRejectCalcium/Magnesium Chloride SolutionRO PermAdvancedFiltrationUVOxidationLowPressure ROWAC WaterSoftenerFilter BWKeep produced water anaerobicFilter colloidal material effectivelyRemove polyvalent cations that formfouling compounds as they are concentratedConcentrate monovalent ionic speciesEvaporate residualCDM High Recovery RO Treatment ProcessHow it Looks:MicrofiltrationSkidsWACSoftenersUV, CartridgeFiltersPump SkidRO SkidPilot Test – Powder River BasinPilot Test ResultsTreated > 3M gallons at 97% recoveryTreated >500,000 gallons at 98% recoveryHigh product water quality (EC < 400 mS/cm)UV disinfection reduced bacteriaWAC softening excellent: <0.1 mg/L TH as CaCO3consistently achieved with no regeneration over thetestperiod.Overall recovery limited by sodium bicarbonate solubility(8.5% wt) at the feed conditionsIdentified filtration as key step! Incoming TSS was 10 timesadvertised.EvaporatorConcentrateSodiumCarbonateByproductCASE STUDY #1:Coalbed Natural GasPowder River Basin in MontanaFeed Quality and Effluent TargetsParameter FeedEffluentTargetsConductivity 2,933 <1,000Hardness (CaCO3) 33Sodium 787Bicarbonate 2,047Total Nitrogen 2.0 1.1SAR 61 <3All values in mg/LCase Study@ PRBProject SpecificsModular Flow Increments: 5-10,000 bbl/d every six monthsFinal Design Flow: 35,000 bbl/dayDesign/Build/Own/OperateIncludes Brine DisposalLong-term Operating ContractCase Study@ PRBComparison to IX TechnologyBasis: 35,000 bbl/d Feed at EC: 2,900, SAR: 61Treatment to EC: 1,000, SAR: 3PerformanceParameterCDM RO Processwith ZLDCurrent IXTechnologyOverall Recovery 100% 97+%Bypass of Untreated Water 0% 8%Effluent ElectricalConductivity (EC)235μS/cm 1,000μS/cmOff-Site Brine Disposal 0 bbl/wk 4,800 bbl/wkBrine CompositionSodium Bicarbonate(97% Pure)Sodium Chloride(acidic)Gypsum Addition for SARAdjustment0 tons/yr 865 tons/yrAcid Consumption(32% HCl)<750 gal/wk 40,000 gal/wkCase Study@ PRBProjected Cost for CDM Process35,000 bbl/dTreatment Costs: $0.14/bbl•Includes all Equipment, Consumables and Operations•Does not include power, gasBrine Disposal Costs:1)Sheridan Commercial Disposal Well: $0.18/bbl2)Evaporator Alternative: $0.08/bbl–$2.25 million equipment–Estimated costs includes capital &O&M–Does not include gas–75% volume reduction (75% of the 3% residual fromthe process)Total Projected Cost: $0.22 to $0.32/bblCase Study@ PRBCASE STUDY #2:Tight Sand GasPiceance Basin,ColoradoFeed Quality and Effluent TargetsParameter FeedEffluentTargetsTDS 11,215 <500Hardness (CaCO3) 213Sodium 4,036Bicarbonate 2,059Chloride 5,202Sulfate 21Oil/Grease 438 <10Silica 119All values in mg/LCase Study@ PiceanceProject SpecificsDesign/Build/Own/Operate90% Reduction in VolumeDoesn’t Include Brine DisposalLimited Space for PondsTotal Flow: 20,000 bbl/day5+ Year ContractCase Study@ PiceanceCDM Treatment ProcessLimeDistillatePermProducedWaterEffluentDischargeSaturatedBrine SolutionRejectGasH2SO4OilMgSO4SludgeDisposalDGFCDMProcessSolids ContactClarifierEvaporator(Optional)FilterPressCase Study@ PiceancePerformance and Cost SummaryEffluent TDS: 478 mg/LRecovery: 90% (1,200 psig)Meets all other target standardsBy-products:–Oil: 10 bbl/d–Lime Sludge: 4.5 wet tons/dChemical Usage (for added steps):–Sulfuric Acid: 0.4 lbs/bbl–Magnesium Sulfate: 0.15 lbs/bbl–Lime: 0.084 lbs/bblCost: $1.65 – 1.95/bblCase Study@ PiceanceQuestions & AnswersCost-effective with waterrecoveries up to 97 – 98%Little chemical additionrequired; continuous orintermittentMinimal membrane foulingHigh quality effluent thatcan meet current and futureregulatory standardsModular systemconfigurationsBroad application acrossbasins