Water treatment method for heavy oil production
AssigneeGE Ionics, Inc.
InventorWilliam Heins
Life of this patent
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Abstract
A process for treating produced water to generate high pressure steam. Produced water from heavy oil recovery operations is treated by first removing oil and grease. Pretreated produced water is then fed to an evaporator. Up to 95% or more of the pretreated produced water stream is evaporated to produce (1) a distillate having a trace amount of residual solutes therein, and (2) evaporator blowdown containing substantially all solutes from the produced water feed. The distillate may be directly used, or polished to remove the trace residual solutes before being fed to a steam generator. Steam generation in a packaged boiler, such as a water tube boiler having a steam drum and a mud drum with water cooled combustion chamber walls, produces 100% quality high pressure steam for down-hole use.
Claims54
A process for producing steam for downhole injection in the recovery of heavy oil, said process comprising:
- (a) providing an oil/water mixture gathered from an oil/water collection well;
- (b) separating oil from said oil/water mixture to provide an oil product and a produced water product containing oil therein;
- (c) de-oiling said oil containing produced water product to at least partially provide an evaporator feedwater stream, said evaporator feedwater stream comprising water, dissolved gases, and dissolved solutes, said dissolved solutes comprising silica;
- (d) providing an evaporator having a plurality of heat transfer elements, a liquid containing sump reservoir, and a recirculating pump to recycle liquid from said sump into a heat transfer relationship with said heat transfer elements;
- (e) injecting said evaporator feedwater stream into said evaporator and evaporating a portion of said feedwater stream to produce a concentrated brine;
- (f) recirculating said concentrated brine in said evaporator;
- (g) adding a selected base in a manner to raise the pH of said concentrated brine to achieve a preselected pH level to enhance solubility of said silica, by adding said selected base to one or more of (i) said evaporator feedwater stream, or (ii) said liquid containing sump reservoir, or (iii) said recirculating concentrated brine;
- (h) distributing said concentrated brine on a first surface of at least one of said plurality of heat transfer elements to generate a steam vapor;
- (i) slightly compressing said steam vapor to produce a compressed steam vapor;
- (j) directing said compressed steam vapor to a second surface of at least one of said plurality of heat transfer elements to condense said compressed steam vapor and to form a distillate
- (k) collecting said distillate stream;
- (l) discharging at least some of said concentrated brine as an evaporator blowdown stream;
- (m) introducing said distillate stream into a steam generator, to produce
- (i) high pressure steam,
- (ii) a boiler blowdown stream, said boiler blowdown stream comprising water and residual dissolved solids;
- (n) injecting said high pressure steam in an injection well to fluidize oil present in a selected geological formation, to produce an oil and water mixture;
- (o) gathering said oil/water mixture.
A process for treatment of a produced water stream resulting from the production of oil from heavy oil reserves, wherein said treatment comprises:
- (a) evaporation of said produced water stream at a pH of at least 10.5 to generate (i) a distillate stream at about 95% or more by volume of said produced water stream and (ii) a blowdown stream at about 5% or less by volume of said produced water stream;
- (b) generating a steam stream at about 100% quality and at about 1000 pounds per square inch pressure or more from said distillate stream, and wherein said steam stream comprises at least about 70% by weight of said distillate stream, and generating a blowdown stream of at least about 30% or less by weight of said distillate stream.
Dependencies are inferred from the claim text.