Water treatment method for heavy oil production using calcium sulfate seed slurry evaporation

• US 7,717,174 B2
• Filed: 10/16/2008
• Issued: 05/18/2010
• Est. Priority Date: 05/07/1999
• Status: Expired due to Term

• Current Assignee: GE Ionics Incorporated (Veolia Environnement SA)
• Original Assignee: GE Ionics Incorporated (Veolia Environnement SA)
• Inventors: Heins, William F.
• Primary Examiner(s): Suchfield; George
• Application Number:
  US12/252,783
• Publication Number:
  US 20090078416A1
• Time in Patent Office: 579 Days
• Field of Search: None
• US Class Current: 166/267
• CPC Class Codes: C02F 1/02 by heating methods of steam generation F22B; preheating boiler feed-water or accumulating preheated boiler feed-water F22D
• CPC Class Codes: C02F 1/04 by distillation or evaporation
• CPC Class Codes: C02F 1/041 by means of vapour compression
• CPC Class Codes: C02F 1/048 Purification of waste water by evaporation
• CPC Class Codes: C02F 1/08 Thin film evaporation
• CPC Class Codes: C02F 1/40 Devices for separating or removing fatty or oily substances or similar floating material cleaning or keeping clear the surface of open water from oil or like materials E02B15/04; devices in sewers for separating liquid or solid substances from sewage E03F5/14, e.g. for use in drains leading to the sewer E03F5/16
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 1/46 by electrochemical methods
• CPC Class Codes: C02F 1/469 by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
• CPC Class Codes: C02F 1/56 Macromolecular compounds
• CPC Class Codes: C02F 1/66 by neutralisation; pH adjustment for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58
• CPC Class Codes: C02F 2103/023 Water in cooling circuits
• CPC Class Codes: C02F 2103/10 from quarries or from mining activities
• CPC Class Codes: C02F 2103/365 from petrochemical industry (e.g. refineries)
• CPC Class Codes: C02F 9/00 Multistage treatment of water, waste water or sewage
• CPC Class Codes: E21B 43/2406 Steam assisted gravity drainage [SAGD]
• CPC Class Codes: E21B 43/2408 SAGD in combination with other methods
• CPC Class Codes: Y10S 159/901 Promoting circulation
• CPC Class Codes: Y10S 203/17 Saline water conversion

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. Feedwater is then acidified and steam stripped to remove alkalinity and dissolved non-condensable gases. 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.

Claims

1. A process for treatment of a produced water stream resulting from the production of oil from heavy oil reserves, said produced water stream comprising dissolved solutes including calcium, sulfate, silica, alkalinity, and non-condensable gases, and wherein said treatment comprises:

(a) acidification of said produced water stream, to remove alkalinity by conversion to free carbon dioxide;

(b) steam stripping said produced water stream to remove said non-condensable gases and said carbon dioxide produced in said alkalinity removal step;

(c) evaporation of said produced water stream to produce a slurry comprising water, dissolved solutes, calcium sulfate, and silica, 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;

(d) 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 about 30% or less by weight of said distillate stream.

2. The process as set forth in claim 1, wherein said steam stream comprises at least 95% by weight of said distillate stream.

3. The process as set forth in claim 2, wherein said steam stream comprises at least 98% by weight of said distillate stream.

4. The process as set forth in claim 3, where said blowdown stream is added to and mixed with said produced water stream prior to evaporation of said produced water stream.

5. The process as set forth in claim 3, wherein evaporation of said produced water stream is accomplished in a falling film evaporator.

6. The process as set forth in claim 1, wherein the produced water stream is treated with acid to lower the pH to convert alkalinity to free carbon dioxide.

7. The process as set forth in claim 1, wherein said evaporator comprises a heat transfer surface, and wherein said slurry of calcium sulfate and silica is maintained at a preselected concentration for preferential precipitation of said calcium said sulfate and said silica to said slurry rather than to said heat transfer surfaces of said evaporator.