Patent ID: 7681643
Filing Date: 2010-03-23
Classification: E21B,Y10S

Abstract:
1. 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 silica, 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.