Method of flash-cooling produced water and heating steam generator feedwater
First Claim
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1. A method of recovering oil and cooling produced water comprising:
- recovering an oil-water mixture from an oil-bearing formation;
separating the oil from the oil-water mixture to yield the produced water;
directing the produced water through a plurality of flash evaporators connected in series;
cooling the produced water as the produced water flows through the series of flash evaporators by varying the pressure in the flash evaporators such that the produced water experiences successive pressure drops in the flash evaporators as the produced water flows through the plurality of flash evaporators, causing a portion of the produced water in each flash evaporator to be converted to vapor;
preheating a steam generator feedwater by transferring heat from the vapor to the steam generator feedwater;
after preheating the steam generator feedwater, directing the steam generator feedwater to a steam generator and generating steam; and
injecting the steam into the oil-bearing formation or injection well.
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Abstract
An oil recovery process where produced water is cooled through a flash evaporization process and the resulting vapor is utilized to heat steam generator feedwater.
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Citations
31 Claims
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1. A method of recovering oil and cooling produced water comprising:
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recovering an oil-water mixture from an oil-bearing formation; separating the oil from the oil-water mixture to yield the produced water; directing the produced water through a plurality of flash evaporators connected in series; cooling the produced water as the produced water flows through the series of flash evaporators by varying the pressure in the flash evaporators such that the produced water experiences successive pressure drops in the flash evaporators as the produced water flows through the plurality of flash evaporators, causing a portion of the produced water in each flash evaporator to be converted to vapor; preheating a steam generator feedwater by transferring heat from the vapor to the steam generator feedwater; after preheating the steam generator feedwater, directing the steam generator feedwater to a steam generator and generating steam; and injecting the steam into the oil-bearing formation or injection well. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of recovering oil from an oil-bearing formation comprising:
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recovering an oil-water mixture from the oil-bearing formation; separating the oil from the oil-water mixture to produce the oil and produced water; directing a feedwater to a steam generator and producing steam; injecting the steam into the oil-bearing formation or an injection well; evaporating a portion of the produced water to produce a vapor by directing the produced water through a plurality of flash evaporators and causing a portion of the produced water in each flash evaporator to be converted to the vapor; transferring heat from the vapor to the feedwater so as to heat the feedwater prior to the feedwater reaching the steam generator; and wherein transferring heat from the vapor to the feedwater includes directing the vapor and the feedwater to a heat exchanger and transferring heat from the vapor to the feedwater in the heat exchanger. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for cooling produced water separated from a recovered oil-water mixture and pre-heating a steam generator feedwater used for generating steam for injection into an oil-bearing formation, the system comprising:
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an oil-water separation unit for receiving the recovered oil-water mixture and separating the oil from the oil-water mixture to produce oil and the produced water; a cooling unit comprising a series of operatively interconnected stages with each stage comprising; i. a flash evaporator having an inlet, outlet and a flash chamber; ii. a heat exchanger operatively connected to the flash evaporator for receiving vapor produced by the flash evaporator; iii. a pressure control circuit operatively connected to the heat exchanger and operative to control the pressure in the flash chamber; a steam generator for generating steam for injection into the oil-bearing formation; a produced water cooling line operatively connected to the flash evaporators of the stages for directing the produced water to the flash evaporators and cooling the produced water and producing the vapor; a first vapor line for directing the vapor from each flash evaporator to one of the heat exchangers; a second vapor line for directing the vapor from each heat exchanger to one of the pressure control circuits; a steam generator feedwater line for directing the feedwater to the heat exchangers where heat is transferred from the vapor in the heat exchangers to the feedwater; and wherein the pressure control circuit decreases the pressure from one flash evaporator to another flash evaporator and wherein succeeding pressure drops occur in the flash evaporators in the direction of flow of the produced water through the flash evaporators. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A system for cooling produced water separated from a recovered oil-water mixture and preheating a steam generator feedwater used for generating steam for injection into an oil-bearing formation, the system comprising:
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an oil-water separation unit for receiving the recovered oil-water mixture and separating oil from the oil-water mixture to produce oil and the produced water; one or more flash evaporators for receiving the produced water and cooling the produced water by flash evaporating the produced water to produce vapor and cooled produced water; one or more heat exchangers for receiving the vapor produced by the one or more flash evaporators; a steam generator for generating steam for injection into the oil-bearing formation; a steam generator feedwater line for feeding the feedwater to the steam generator; the steam generator feedwater line configured to direct the feedwater through the one or more heat exchangers prior to the feedwater reaching the steam generator wherein heat is transferred from the vapor to the steam generator feedwater; and wherein the heat exchanger isolates the vapor from the steam generator feedwater and heat is transferred from the vapor to the steam generator feedwater. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A method of recovering oil and cooling produced water comprising:
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recovering an oil-water mixture from an oil-bearing formation; separating oil from the oil-water mixture to yield the produced water; directing the produced water through a plurality of flash evaporators connected in series; cooling the produced water as the produced water flows through the series of flash evaporators by varying the pressure in the flash evaporators such that the produced water experiences successive pressure drops in the flash evaporators as the produced water flows through the plurality of flash evaporators, causing a portion of the produced water in each flash evaporator to be converted to vapor; preheating a steam generator feedwater by transferring heat from the vapor to a steam generator feedwater; after preheating the steam generator feedwater, directing the steam generator feedwater to a steam generator and generating steam; injecting the steam into an oil-bearing formation or injection well; and wherein each flash evaporator produces a vapor stream that is directed to and through a heat exchanger and from the heat exchanger to a pressure control device that controls the pressure within the flash evaporator that produced the vapor stream.
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Specification