澳洲大学石油工程讲座59-8500and59-8510-surfacefacilitiesforwaterfloodingandsaltdisposal

1、1SURFACE FACILITIES FOR WATERFLOODING & SALT WATER DISPOSALPublished by Rike Service, Inc.New Orleans, Louisiana (USA)All rights reserved, including the right to reproduce, alter or delete any of this material without written permission, except brief extracts for review.2Handling of water is inheren

2、t to oil & gas operationsMust dispose of produced waterWaterflood projects require handling produced & source waterA major portion of field operation costsFUNDAMENTALS3Four basic steps common to water disposal & waterfloodingCollection from producing or source wellsTreatment to improve quality & pre

3、vent corrosionStorage to provide flexibilityInjection or surface disposalFUNDAMENTALS4Water disposal can be accomplished in several ways:EvaporationRiver and stream disposalTidewater & ocean disposalPressure & gravity injection into subsurface formationsFUNDAMENTALS5Source water for floods may be of

4、 several originsWater associated with oil & gas productionOceans, lakes & riversSubsurface aquifersFUNDAMENTALS6Must obtain approvalApply & present testimonyReservoir dataWell dataSurface facilitiesEconomic feasibility studiesGOVERNMENT REGULATIONS7Agencies involved in USAState regulatorsU.S.G.S.Fis

5、h & wildlife commissionsEnvironmental protection agenciesMore added all the timeGOVERNMENT REGULATIONS8Surface disposal systemsGather water for disposal into pits, streams, tidewater or oceansDESIGN TO MEET REGULATIONS9Leases may be tied into field gathering linesTreat water for removal of oilDESIGN

6、 TO MEET REGULATIONS10May require clarification for stream disposalUnsightly appearance creates problems with land-owners and government inspectorsDESIGN TO MEET REGULATIONS11Subsurface disposal systems & waterflood systemsMust provide all four basic steps (gathering, treating, storage & injection)D

7、ESIGN TO MEET REGULATIONS12Three types of systemsOpenwater in contact with airClosedair excluded from systemSemi-closedoil or gas blanket to exclude airDESIGN TO MEET REGULATIONS13Two main design factorsCharacteristics of water to be injectedCharacteristics of injection wellDESIGN TO MEET REGULATION

8、S14Open 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 SYSTEMS15Closed SystemWater is stable in the formation and if not allowed to come into contact wit

9、h air, it can be injected with minimum treatment.OPEN VS. CLOSED SYSTEMS16Open system processesOil skimmingAerationChemical additionRetention time for settlingFiltrationCorrosion/bacteria controlOPEN VS. CLOSED SYSTEMS17Closed system processesOil skimmingFiltrationCorrosion/bacteria controlOPEN VS.

10、CLOSED SYSTEMS18Advantages of open systemsWhen water contains excessive solidsWhen water gathered from numerous batteriesOPEN VS. CLOSED SYSTEMS19Advantages of closed systemsExclusion of oxygen prevents iron precipitates from formingExclusion of oxygen holds corrosion to lower ratePressure prevents

11、release of carbon dioxide and subsequent precipitation of calcium & magnesiumOPEN VS. CLOSED SYSTEMS20Advantages of closed systemsAerobic bacteria are eliminatedChemical treatment for flocculation is eliminatedWater stability maintained if produced water is re-injectedOPEN VS. CLOSED SYSTEMS21Closed

12、 system requirementsGas seal on all holding tanksOil seal will not exclude airOPEN VS. CLOSED SYSTEMS22Water characteristicsSuspended solids presentCorrosive nature of waterBacterial contentCompatibility of produced & injected waterScale forming tendenciesSUBSURFACE INJECTIONSYSTEM DESIGN23Injection

13、 well characteristicsMechanicsNature of formationSUBSURFACE INJECTIONSYSTEM DESIGN24Types and originsOilSilt & sandIron oxideIron sulfideCalcium carbonateCalcium sulfateBarium sulfateAlgae & fungusSUSPENDED SOLIDS IN WATER25Prevent solids from forming or install facilities to remove them before inje

14、ctingImprove oil treatingUse corrosion resistant materialsUse chemicals to control precipitates, bacteria & algaeSUSPENDED SOLIDS IN WATER26Millipore filter tests determine amount & type of solids at different locationsFilter discs from 5 millimicrons to 0.45 micronsFlow water at constant pressure f

15、or 30 min.Measure filtrate at timed intervalsSUSPENDED SOLIDS IN WATER27Plot volume throughout vs. flow rateAnalyze solids to determine compositionSUSPENDED SOLIDS IN WATER28CORROSIONCorrosion occurs due to natural tendency of steel to revert to iron orePyriteSideriteGoethiteLimoniteComplex sulfides

16、 and others29CORROSIONCorrosion agentsOxygen Hydrogen sulfideCarbon dioxideOrganic acids30CORROSIONOxygen causes the greatest amount of corrosion in salt water systemsRapid pitting of steelGraphitic corrosion of cast ironFouling of system and well with rust31CORROSIONControlling corrosionRemove the

17、agentIsolate metal from the agentInhibit against it32CORROSIONMost systems require removal of oxygenVacuum de-aerationChemical de-aeration with scavengers (Sodium sulfite, sulfur dioxide)33CORROSIONMethods to isolate agents from steelCoatings (cement, organic, ceramic, plastic, etc.)Corrosive resist

18、ant materials (alloys, porcelain, plastic, fiberglass, etc.)34CORROSIONInhibitors are film-forming organic compoundsChange wettability of steelNot effective when oxygen is greater than 1 ppm35BACTERIASulfate reducing bacteriaCauses severe corrosionPlugs off injection wellsSmall curved rod- or spiral

19、-shapedOccur in soil, sewage, fresh water & seawaterAnaerobic, but grow in several ppm O2Not killed by aerationAbundant in produced water36CORROSIONCorrosion process is removal of hydrogen formed at cathodic areas of metalsReduces sulfate to sulfideIncreases corrosion anaerobically37CORROSIONProduct

20、s formed by sulfate reducing bacteriaHydrogen sulfide gasInsoluble ferrous sulfide38CORROSIONResults of sulfate reducing bacteriaContinuous metal loss (electrolysis)Corrosive H2S gas liberatedPlugged injection well (ferrous sulfide)39CORROSIONField testingInject small amount of water into media cond

21、ucive to growth of bacteria at various dilutionsMaintain at temperature of injected water for 3-4 weeksObserve test bottles to determine bacteria presence and count40CORROSIONControl sulfate reducing bacteriaChemical treatmentEliminate dead spots in systems41CORROSIONIron bacteria limited to open sy

22、stemsGrow rapidlyAbstract iron from water and deposit it to outer sheath where it is oxidized to ferric hydroxideControlled by chlorination42COMPATIBILITY OF WATERSMixing causes ions to react and form insoluble precipitatesIron sulfideCalcium carbonateCalcium sulfateBarium sulfateStrontium sulfate43

23、COMPATIBILITY OF WATERSMostly occurs on surface due to better mixingSand reservoirs do not provide enough mixingVuggy limestones could provide enough mixing44COMPATIBILITY OF WATERSGather and inject waters separately in large systemChemically treat water in small systemsSequestrant to hold cation in

24、 solutionPolyphosphate at 2-5 ppm holds calcium ion in solution45COMPATIBILITY OF WATERSIf formation mixing is a problem, pump a barrier of treated water between formation and injection water46EQUIPMENTLines & tubing for gathering & injectionValves & fittings to control flowTanks for skimming, settl

25、ing & holdingAeration to remove acid gas & dissolved ironCoagulation & settling equipment to remove suspended matter47EQUIPMENTDe-aeration equipment to remove oxygenFilters to remove last traces of solids before injectionPumps to transfer water and injectionMiscellaneous (chemical pumps, oil skimmin

26、g vessels, and controls)48LINES & 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)Fiberglass49VALVES & FITTINGSMust meet pressure requirementsMust resist corrosionMust have desirable

27、 operating features in water serviceTry to minimize the number in system50TANKSUse bolted or welded steel tanksWood tanks not recommendedPlastic or vinyl coated tanks sometimes usedFiberglass tanksDesign tank hatches to hold 2-4 oz. gas pressure51AERATION EQUIPMENTSpray ponds where water is sprayed

28、out in fine mistSplash traysAerating slabForced draft aerators to bodily sweep off acid gasesHigh concentrations of H2S require more elaborate systems52COAGULATION & SETTLINGEQUIPMENTMust remove suspended solids after aerationChemicals added upstream of settling basin or tankSettling ponds or basins

29、 may be required for adequate retention time53DE-AERATION EQUIPMENTVacuum de-aeration vessels & equipmentPacked towers with natural gas counterflowChemical de-aeration equipment54FILTER EQUIPMENTProper selection depends on existing conditionsCondition of water to be filteredDesired quality of filter

30、ed waterVolume of water to be filteredEconomics of project55FILTER EQUIPMENTDiatomaceous earth filters produce highest quality waterHigher initial costRequire regular servicingVertical tank tubular elementHorizontal tank leaf type56FILTER EQUIPMENTPressure sand filtersDownflow graded bed filtersDown

31、flow single bed filtersUpflow graded bed filtersMixed media downflow filtersDual flow graded bed filtersCosts depend on flow design & filter media57FILTER EQUIPMENTDownflow graded bed filtersEach bed finer than bed below itFlow rate usually limited to 3 GPM/square footLow solids loading capacity58FI

32、LTER EQUIPMENTDownflow single bed filtersSingle filter media on permeable platesFlow rates as high as 20 GPM/square footPermeable plate distributes fluid during backwashing59FILTER EQUIPMENTUpflow graded bed filtersWater flows through coarser beds first in both filtering and backwashingSolids loadin

33、g capacity is greater than downflowHold flow rates below 6-8 GPM/sq.ft. to prevent fluidization of media60FILTER EQUIPMENTMixed media downflow filtersCoarse media of lower density placed on topSolids loading advantage of upflow without fluidizationDensity differences of media used for grading during

34、 backwash61FILTER 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 others62FILTER EQUIPMENTFilter media usedSandAnthrafiltGraph

35、ilterGarnite63FILTER 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)64PUMPING EQUIPMENTLargest single cost of systemfactors to consider:Volume

36、of waterDischarge pressure requiredSuction head availableSpace requirementsLoad variationsFlexibility requiredPrime mover requiredCorrosive nature of waterPump efficiency65FILTER EQUIPMENTDuplex piston-type pumps used when pressure is below 500 psiLower initial cost/lower maintenance cost85% efficie

37、ncyRod packing & piston cups biggest maintenance problem66FILTER EQUIPMENTMultiplex plunger pumps for pressures above 500 psi90% efficiencyMore costly maintenancePlungers are available in corrosive resistant alloys & materials67FILTER 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 pressure68FILTER EQUIPMENTVertical turbine pu