Solvent-assisted method for mobilizing viscous heavy oil
First Claim
1. A solvent-assisted gravity drainage process for recovering heavy oil from a reservoir penetrated by well means for injecting solvent into the reservoir and producing mobilized oil from the reservoir, comprising:
- mixing at least two solvents, each soluble in oil, at ground surface to form a substantially gaseous solvent mixture;
said solvent mixture having a dew point that substantially corresponds with reservoir pressure and temperature, said solvent mixture further having a vapor/liquid envelope which encompasses the reservoir conditions, so that at the reservoir conditions the solvent mixture is present in both liquid and vapor forms, but predominantly as vapor;
injecting the substantially gaseous solvent mixture into the reservoir to mobilize contained oil; and
recovering said mobilized oil.
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Accused Products
Abstract
The invention provides a solvent-assisted method for mobilizing viscous heavy oil or bitumen in a reservoir under reservoir conditions without the need to adjust the temperature or pressure. The invention utilizes mixtures of hydrocarbon solvents such as ethane, propane and butane, which dissolve in oil and reduce its viscosity. Two or more solvents are mixed in such proportions that the dew point of the solvent mixture corresponds with reservoir temperature and pressure conditions. The solvent mixture, when injected into a reservoir, exists predominantly in the vapor phase, minimizing the solvent requirement. The invention can be practised in the context of paired injector and producer wells, or a single well cyclic system.
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Citations
8 Claims
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1. A solvent-assisted gravity drainage process for recovering heavy oil from a reservoir penetrated by well means for injecting solvent into the reservoir and producing mobilized oil from the reservoir, comprising:
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mixing at least two solvents, each soluble in oil, at ground surface to form a substantially gaseous solvent mixture; said solvent mixture having a dew point that substantially corresponds with reservoir pressure and temperature, said solvent mixture further having a vapor/liquid envelope which encompasses the reservoir conditions, so that at the reservoir conditions the solvent mixture is present in both liquid and vapor forms, but predominantly as vapor; injecting the substantially gaseous solvent mixture into the reservoir to mobilize contained oil; and recovering said mobilized oil. - View Dependent Claims (2)
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3. A process for recovering heavy oil from a reservoir comprising the steps of:
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mixing at least two solvents at ground surface to form a gaseous solvent mixture; injecting said gaseous solvent mixture into the reservoir to produce a mobilized oil, wherein at least a portion of said gaseous solvent mixture forms a liquid in the reservoir; and recovering said mobilized oil. - View Dependent Claims (4, 5)
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6. A process for recovering heavy oil from a reservoir comprising the steps of:
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determining the temperature and pressure of a reservoir; selecting a solvent mixture comprising at least two solvents based on the temperature and pressure of the reservoir, wherein a dew point of said solvent mixture corresponds with the temperature and pressure of the reservoir, and wherein said solvent mixture is substantially a gas at ground surface; injecting said solvent mixture to produce a mobilized oil; and recovering said mobilized oil. - View Dependent Claims (7, 8)
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Specification