资源描述
Handling of water is inherent to oil&gas operationsMust dispose of produced waterWaterflood projects require handling produced&source waterA major portion of field operation costsFUNDAMENTALS1Four basic steps common to water disposal&waterfloodingCollection from producing or source wellsTreatment to improve quality&prevent corrosionStorage to provide flexibilityInjection or surface disposalFUNDAMENTALS2Water disposal can be accomplished in several ways:EvaporationRiver and stream disposalTidewater&ocean disposalPressure&gravity injection into subsurface formationsFUNDAMENTALS3Source water for floods may be of several originsWater associated with oil&gas productionOceans,lakes&riversSubsurface aquifersFUNDAMENTALS4Must obtain approvalApply&present testimonyReservoir dataWell dataSurface facilitiesEconomic feasibility studiesGOVERNMENT REGULATIONS5Agencies involved in USAState regulatorsU.S.G.S.Fish&wildlife commissionsEnvironmental protection agenciesMore added all the timeGOVERNMENT REGULATIONS6Surface disposal systemsGather water for disposal into pits,streams,tidewater or oceansDESIGN TO MEET REGULATIONS7Leases may be tied into field gathering linesTreat water for removal of oilDESIGN TO MEET REGULATIONS8May require clarification for stream disposalUnsightly appearance creates problems with land-owners and government inspectorsDESIGN TO MEET REGULATIONS9Subsurface disposal systems&waterflood systemsMust provide all four basic steps(gathering,treating,storage&injection)DESIGN TO MEET REGULATIONS10Three types of systemsOpenwater in contact with airClosedair excluded from systemSemi-closedoil or gas blanket to exclude airDESIGN TO MEET REGULATIONS11Two main design factorsCharacteristics of water to be injectedCharacteristics of injection wellDESIGN TO MEET REGULATIONS12Open SystemWater stability in the formation has been lost by production process,reducing pressure and temperature and removing inorganic and organic gas.Water must be treated anyway.OPEN VS.CLOSED SYSTEMS13Closed SystemWater is stable in the formation and if not allowed to come into contact with air,it can be injected with minimum treatment.OPEN VS.CLOSED SYSTEMS14Open system processesOil skimmingAerationChemical additionRetention time for settlingFiltrationCorrosion/bacteria controlOPEN VS.CLOSED SYSTEMS15Closed system processesOil skimmingFiltrationCorrosion/bacteria controlOPEN VS.CLOSED SYSTEMS16Advantages of open systemsWhen water contains excessive solidsWhen water gathered from numerous batteriesOPEN VS.CLOSED SYSTEMS17Advantages of closed systemsExclusion of oxygen prevents iron precipitates from formingExclusion of oxygen holds corrosion to lower ratePressure prevents release of carbon dioxide and subsequent precipitation of calcium&magnesiumOPEN VS.CLOSED SYSTEMS18Advantages of closed systemsAerobic bacteria are eliminatedChemical treatment for flocculation is eliminatedWater stability maintained if produced water is re-injectedOPEN VS.CLOSED SYSTEMS19Closed system requirementsGas seal on all holding tanksOil seal will not exclude airOPEN VS.CLOSED SYSTEMS20Water characteristicsSuspended solids presentCorrosive nature of waterBacterial contentCompatibility of produced&injected waterScale forming tendenciesSUBSURFACE INJECTIONSYSTEM DESIGN21Injection well characteristicsMechanicsNature of formationSUBSURFACE INJECTIONSYSTEM DESIGN22Types and originsOilSilt&sandIron oxideIron sulfideCalcium carbonateCalcium sulfateBarium sulfateAlgae&fungusSUSPENDED SOLIDS IN WATER23Prevent solids from forming or install facilities to remove them before injectingImprove oil treatingUse corrosion resistant materialsUse chemicals to control precipitates,bacteria&algaeSUSPENDED SOLIDS IN WATER24Millipore filter tests determine amount&type of solids at different locationsFilter discs from 5 millimicrons to 0.45 micronsFlow water at constant pressure for 30 min.Measure filtrate at timed intervalsSUSPENDED SOLIDS IN WATER25Plot volume throughout vs.flow rateAnalyze solids to determine compositionSUSPENDED SOLIDS IN WATER26CORROSIONCorrosion occurs due to natural tendency of steel to revert to iron orePyriteSideriteGoethiteLimoniteComplex sulfides and others27CORROSIONCorrosion agentsOxygen Hydrogen sulfideCarbon dioxideOrganic acids28CORROSIONOxygen causes the greatest amount of corrosion in salt water systemsRapid pitting of steelGraphitic corrosion of cast ironFouling of system and well with rust29CORROSIONControlling corrosionRemove the agentIsolate metal from the agentInhibit against it30CORROSIONMost systems require removal of oxygenVacuum de-aerationChemical de-aeration with scavengers(Sodium sulfite,sulfur dioxide)31CORROSIONMethods to isolate agents from steelCoatings(cement,organic,ceramic,plastic,etc.)Corrosive resistant materials(alloys,porcelain,plastic,fiberglass,etc.)32CORROSIONInhibitors are film-forming organic compoundsChange wettability of steelNot effective when oxygen is greater than 1 ppm33BACTERIASulfate reducing bacteriaCauses severe corrosionPlugs off injection wellsSmall curved rod-or spiral-shapedOccur in soil,sewage,fresh water&seawaterAnaerobic,but grow in several ppm O2Not killed by aerationAbundant in produced water34CORROSIONCorrosion process is removal of hydrogen formed at cathodic areas of metalsReduces sulfate to sulfideIncreases corrosion anaerobically35CORROSIONProducts formed by sulfate reducing bacteriaHydrogen sulfide gasInsoluble ferrous sulfide36CORROSIONResults of sulfate reducing bacteriaContinuous metal loss(electrolysis)Corrosive H2S gas liberatedPlugged injection well(ferrous sulfide)37CORROSIONField testingInject small amount of water into media conducive to growth of bacteria at various dilutionsMaintain at temperature of injected water for 3-4 weeksObserve test bottles to determine bacteria presence and count38CORROSIONControl sulfate reducing bacteriaChemical treatmentEliminate dead spots in systems39CORROSIONIron bacteria limited to open systemsGrow rapidlyAbstract iron from water and deposit it to outer sheath where it is oxidized to ferric hydroxideControlled by chlorination40COMPATIBILITY OF WATERSMixing causes ions to react and form insoluble precipitatesIron sulfideCalcium carbonateCalcium sulfateBarium sulfateStrontium sulfate41COMPATIBILITY OF WATERSMostly occurs on surface due to better mixingSand reservoirs do not provide enough mixingVuggy limestones could provide enough mixing42COMPATIBILITY OF WATERSGather and inject waters separately in large systemChemically treat water in small systemsSequestrant to hold cation in solutionPolyphosphate at 2-5 ppm holds calcium ion in solution43COMPATIBILITY OF WATERSIf formation mixing is a problem,pump a barrier of treated water between formation and injection water44EQUIPMENTLines&tubing for gathering&injectionValves&fittings to control flowTanks for skimming,settling&holdingAeration to remove acid gas&dissolved ironCoagulation&settling equipment to remove suspended matter45EQUIPMENTDe-aeration equipment to remove oxygenFilters to remove last traces of solids before injectionPumps to transfer water and injectionMiscellaneous(chemical pumps,oil skimming vessels,and controls)46LINES&TUBINGBare steel pipeCement lined steel pipe&tubingPlastic lined steel pipe&tubingCement-asbestos pipe(200 psi MWP)Cast iron pipe(350 psi MWP)Plastic pipe(PVC)Fiberglass47VALVES&FITTINGSMust meet pressure requirementsMust resist corrosionMust have desirable operating features in water serviceTry to minimize the number in system48TANKSUse bolted or welded steel tanksWood tanks not recommendedPlastic or vinyl coated tanks sometimes usedFiberglass tanksDesign tank hatches to hold 2-4 oz.gas pressure49AERATION EQUIPMENTSpray ponds where water is sprayed out in fine mistSplash traysAerating slabForced draft aerators to bodily sweep off acid gasesHigh concentrations of H2S require more elaborate systems50COAGULATION&SETTLINGEQUIPMENTMust remove suspended solids after aerationChemicals added upstream of settling basin or tankSettling ponds or basins may be required for adequate retention time51DE-AERATION EQUIPMENTVacuum de-aeration vessels&equipmentPacked towers with natural gas counterflowChemical de-aeration equipment52FILTER EQUIPMENTProper selection depends on existing conditionsCondition of water to be filteredDesired quality of filtered waterVolume of water to be filteredEconomics of project53FILTER EQUIPMENTDiatomaceous earth filters produce highest quality waterHigher initial costRequire regular servicingVertical tank tubular elementHorizontal tank leaf type54FILTER EQUIPMENTPressure sand filtersDownflow graded bed filtersDownflow single bed filtersUpflow graded bed filtersMixed media downflow filtersDual flow graded bed filtersCosts depend on flow design&filter media55FILTER EQUIPMENTDownflow graded bed filtersEach bed finer than bed below itFlow rate usually limited to 3 GPM/square footLow solids loading capacity56FILTER EQUIPMENTDownflow single bed filtersSingle filter media on permeable platesFlow rates as high as 20 GPM/square footPermeable plate distributes fluid during backwashing57FILTER EQUIPMENTUpflow graded bed filtersWater flows through coarser beds first in both filtering and backwashingSolids loading capacity is greater than downflowHold flow rates below 6-8 GPM/sq.ft.to prevent fluidization of media58FILTER EQUIPMENTMixed media downflow filtersCoarse media of lower density placed on topSolids loading advantage of upflow without fluidizationDensity differences of media used for grading during backwash59FILTER EQUIPMENTDual flow graded bed filterWater enters top and bottomFine bed in middle with coarser beds on each sideFlow rates as high as 40 GPM/sq.ft.Screen over outlet to prevent loss of fine filter mediaBackwashing same as others60FILTER EQUIPMENTFilter media usedSandAnthrafiltGraphilterGarnite61FILTER EQUIPMENTBackwashing required with all filtersVelocity sufficient to fluidize media to 150%of volumeFrequent backwashing required indicates poor water quality at inlet(50 ppm or less turbidity at inlet)62PUMPING EQUIPMENTLargest single cost of systemfactors to consider:Volume of waterDischarge pressure requiredSuction head availableSpace requirementsLoad variationsFlexibility requiredPrime mover requiredCorrosive nature of waterPump efficiency63FILTER EQUIPMENTDuplex piston-type pumps used when pressure is below 500 psiLower initial cost/lower maintenance cost85%efficiencyRod packing&piston cups biggest maintenance problem64FILTER EQUIPMENTMultiplex plunger pumps for pressures above 500 psi90%efficiencyMore costly maintenancePlungers are available in corrosive resistant alloys&materials65FILTER EQUIPMENTCentrifugal pumps for large volumes at low pressuresRequire less spaceLow initial costLow maintenance cost if corrosion not a problem70%efficiency(range of 40-85)Multistage centrifugal pumps can handle some pressure66FILTER EQUIPMENTVertical turbine pumps are sometimes adaptableNot good for changing pressure and volumeLow initial cost and easily maintained67FILTER EQUIPMENTSuction piping important in pump installationVapor pressure of water must be exceeded to prevent flashingFriction head of suction lines to pumpAcceleration head to meet pump requirementsNPSH to lift suction valve springs and fill chamber68FILTER EQUIPMENTPrime movers are either electric motors or gas enginesBelt drivenDirect drive with flexible couplingDirect drive with speed reducer69MISCELLANEOUS EQUIPMENTChemical pumps resistant to acid,caustic&organic chemicalsPressure and water level controlsHigh-low mercury switchesAutomatic on and off pump motor switches70MISCELLANEOUS EQUIPMENTSpecial oil removal equipmentMust remove final traces of oil before disposal(10 ppm or less)Tanks with hay sectionsOil precipitator7172737475Gibbs Flotation Unit7677DIATOMITE TUBULAR FILTER78Leaf Type Diatomite Filter79Size*(Microns)Type A Type B Type C Type DType E402.56.012.017.524.040-208.015.525.532.052.020-1014.033.529.032.018.510-619.022.019.516.04.56-237.521.513.52.51.0219.01.50.5-Particle Size Distribution for Several Grades of Filter Aid Offered by One Manufacturer*Equivalent sphere size by sedimentation methods80818283谢谢！
展开阅读全文