Process for purification of produced water
AssigneeAquatech International Corporation
InventorsRavi Chidambaran, Narendra Singh Bisht, Pavan Raina
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Abstract
We provide a process for treatment of produced water, including but not limited to water produced by a “steam flood” process for extraction of oil from oil sands, including the removal of color from the water. This removal may be accomplished through addition of color-removal polymers and flocculents. This process may also be useful for other water treatment processes including reverse osmosis and filtration.
Claims21
A process for purification of water for use in a boiler for a steam flood process, comprising:
- collecting produced water including an oil/water mixture from an oil well;
- separating and recovering oil from the produced water;
- decreasing the pH of the produced water by addition of acid;
- removing color, organics, and silica from the produced water;
- adding a flocculent, including, optionally, a coagulant and a polyelectrolyte, to the produced water to aggregate solids in the produced water;
- removing solids from the produced water, thereby producing sludge;
- conditioning and disposing of the sludge;
- sending the produced water to an evaporator, producing a distillate stream and a brine stream;
- sending the distillate stream to a boiler for use as steam in injection to an oil well.
The process of claim 8, further comprising, after precipitating silica from the produced water, removing the precipitated silica as a second sludge;
- and
- conditioning and disposing of the second sludge.
A process for preconditioning water for use in an evaporation or reverse osmosis treatment, comprising:
- providing a water stream including color;
- removing color, organics, and silica from the water stream by the steps of:
- adding an acid;
- adding a color removal chemical;
- and
- adding a flocculent to aggregate solids in the water stream;
- removing the solids from the water stream;
- increasing the pH of the water stream;
- and
- sending the produced water to at least one of a evaporator and a reverse osmosis unit.
A process for preconditioning water for use in reverse osmosis or evaporative treatment, comprising:
- providing water comprising silica, color, and organics;
- decreasing the pH of the water by addition of acid;
- removing color, organics, and silica from the water by addition of color-removal chemicals;
- adding a flocculent to the water to aggregate solids in the water;
- removing aggregated solids from the produced water, thereby producing sludge;
- conditioning and disposing of the sludge;
- mixing the water with one or more of lime, magnesium oxide, calcium oxide, and sodium hydroxide, thereby precipitating additional solids;
- removing the additional solids as a second sludge
- conditioning and disposing of the second sludge;
- and
- sending the water to at least one of an evaporator or reverse osmosis unit.
A process for purification of water for use in a boiler for a steam flood process, comprising:
- collecting produced water including an oil/water mixture from an oil well;
- separating and recovering oil from the produced water;
- decreasing the pH of the produced water by addition of acid;
- removing color, organics, and silica from the produced water;
- adding a flocculent, including, optionally, a coagulant and a polyelectrolyte, to the produced water to aggregate solids in the produced water;
- removing solids from the produced water, thereby producing sludge;
- conditioning and disposing of the sludge;
- mixing the produced water with one or more of lime, magnesium oxide, magnesium hydroxide, calcium oxide, and sodium hydroxide, thereby precipitating silica from the produced water;
- removing precipitated silica as a second sludge;
- conditioning and disposing of the second sludge;
- sending the produced water to an evaporator, producing a distillate stream and a brine stream;
- sending the distillate stream to a boiler for use as steam in injection to an oil well;
- and
- sending a portion of the brine stream to a crystallizer for removal of additional distillate and production of a slurry to achieve zero liquid discharge without tar formation.
A two-stage process for silica reduction from water, comprising:
- from a water stream comprising silica, water, and organics, at least some silica with color and organics;
- precipitating additional silica from the water stream by addition of at least one silica-precipitating compound selected from the group consisting of lime, magnesium oxide, magnesium hydroxide, calcium oxide, and sodium hydroxide upstream of an evaporator or reverse osmosis system.
Dependencies are inferred from the claim text.