Treatment of brines for deep well injection

A process to recover heavy hydrocarbon oil by in situ dissolution of at least a portion of a first geological formation containing quantities of heavy hydrocarbon oil, comprising:

• injecting steam into the first geological formation to heat the heavy hydrocarbon oils in the first geological formation and to mobilize least a portion of said heavy hydrocarbon oils in the first geological formation, to produce a mixture of oil and produced water, wherein said produced water comprises condensate from said steam;
• separating oil from said mixture of oil and produced water to provide (i) an oil product, and (ii) a produced water composition comprising water and oil;
• de-oiling said produced water composition to at least partially provide an evaporator feedwater stream, said evaporator feedwater stream comprising water, dissolved gases, and dissolved solutes, said dissolved solutes comprising calcium, sulfate, and silica;
• providing a crystallizing evaporator having a plurality of heat transfer elements, a liquid containing sump reservoir, and a recirculating pump to recycle liquid from said liquid containing sump reservoir into a heat transfer relationship with said plurality of heat transfer elements;
• seeding said liquid containing sump reservoir with a selected quantity of calcium sulfate seed crystals, and forming a circulating brine comprising a slurry of water and calcium sulfate seed crystals, wherein said slurry is maintained at a preselected concentration for preferential precipitation of said calcium, said sulfate, and said silica in said evaporator feedwater stream to said calcium sulfate seed crystals rather than to said heat transfer surfaces of said crystallizing evaporator;
• feeding the evaporator feedwater stream to the crystallizing evaporator, and producing (i) a distillate stream, and (ii) a concentrated blowdown brine slurry stream comprising water, dissolved solids, said dissolved solids comprising one or more scale forming species, and suspended solids, said suspended solids comprising calcium sulfate and silica;
• feeding said distillate stream to a boiler, and producing steam for injection into said first geological formation;
• removing said suspended solids from said concentrated blowdown brine slurry stream to produce a substantially suspended solids free clear brine liquor;
• diluting said substantially suspended solids free clear brine liquor with an aqueous diluent to produce a clear brine solution, said clear brine solution comprising water and dissolved solids, said dissolved solids comprising scale forming species at a level of at about 10% or more below the level of said one or more scale forming species in said substantially solids free clear brine liquor;
• and
• injecting said clear brine solution into a second geological formation, thereby providing disposal of said clear brine solution.

A process for treatment of waste brines produced during steam generation operations associated with the recovery of heavy hydrocarbon oil by in situ dissolution of at least a portion of a first geological formation containing quantities of heavy hydrocarbon oil, said process comprising:

• injecting steam into the first geological formation to heat the heavy hydrocarbon oils in the first geological formation and to mobilize least a portion of said hydrocarbon oils in the first geological formation, to produce a mixture of oil and produced water, wherein said produced water comprises condensate from said steam;
• separating oil from said mixture of oil and produced water to provide (i) an oil product, and (ii) a produced water composition comprising water and oil;
• de-oiling said produced water composition to at least partially provide an evaporator feedwater stream, said evaporator feedwater stream comprising water, dissolved gases, and dissolved solutes, said dissolved solutes comprising calcium, sulfate, and silica;
• providing a crystallizing vapor recompression evaporator having a plurality of heat transfer elements, a liquid containing sump reservoir, and a recirculating pump to recycle liquid from said liquid containing sump reservoir into a heat transfer relationship with said plurality of heat transfer elements;
• seeding said liquid containing sump reservoir with a selected quantity of calcium sulfate seed crystals, and forming a circulating brine comprising a slurry of water and calcium sulfate seed crystals, wherein said slurry is maintained at a preselected concentration for preferential precipitation of said calcium, said sulfate, and said silica to said calcium sulfate seed crystals rather than to said heat transfer surfaces of said crystallizing evaporator;
• acidifying said evaporator feedwater stream, to convert non-hydroxide alkalinity to carbon dioxide;
• steam stripping said acidified evaporator feedwater stream, and removing said non-condensable gases and said carbon dioxide;
• feeding the acidified and steam stripped evaporator feedwater stream to the crystallizing evaporator, and producing (i) a distillate stream, and (ii) a concentrated blowdown brine slurry stream comprising water, dissolved solids, and suspended solids, said suspended solids comprising calcium sulfate and silica;
• feeding at least some of said distillate stream to a boiler, and producing high pressure steam for injection into said first geologic formation;
• removing said suspended solids from said concentrated blowdown brine slurry stream to produce a substantially suspended solids free clear brine liquor;
• diluting said substantially suspended solids free clear brine liquor with at least a portion of said distillate stream to produce a clear brine solution, said clear brine solution comprising water and dissolved solids, said dissolved solids comprising silica at a level of below the level of silica in said clear brine solution;
• injecting said clear brine solution into a second geological formation, thereby providing disposal of said clear brine solution.