Method and plant or increasing oil recovery by gas injection
AssigneeStatoil ASA
InventorsOla Olsvik, Erling Rytter, Jostein Sogge, Rune Kvale, Sjur Haugen, Jan Grøntvedt
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Abstract
A method and a plant for simultaneous production of a gas for injection into an oil field and production of methanol, dimethyl ether and/or other oxygenated hydrocarbons or production of higher hydrocarbons from natural gas is disclosed. An air separation unit (ATR) for production of pure nitrogen for injection and pure oxygen for production of synthesis gas (“syngas”) by authermal reformation of a natural gas is an essential part of the method and plant.
Claims21
A method for increasing oil recovery from an oil reservoir in which method gas is injected into the reservoir, comprising:
- separating air into an oxygen-rich fraction and a nitrogen-rich fraction;
- providing a natural gas stream and leading the natural gas stream and at least a part of the oxygen-rich fraction to a reformer for conversion to synthesis gas mainly comprising H2, CO, and CO2 in addition to lower amounts of non-converted methane, water vapor, and oxygen;
- synthesizing methanol or other oxygenated hydrocarbons or higher hydrocarbons from the synthesis gas in a synthesis unit;
- withdrawing a waste gas from the synthesis unit;
- and
- injecting the nitrogen-rich fraction and at least a part of the waste gas into the oil reservoir to increase the oil recovery from the reservoir.
A plant for providing gas for downhole injection for pressure support in an oil reservoir for recovery of hydrocarbons and production of methanol, dimethyl ether and/or other oxygenated hydrocarbons or for production of higher hydrocarbons from natural gas, comprising:
- an air separation unit for production of an oxygen-rich fraction for supply to processes that require oxygen, and a nitrogen fraction for injection;
- a reformer for conversion of a mixture of natural gas, water, and oxygen from the air separation unit into a synthesis gas comprising mainly H2, CO, CO2 and small amounts of methane;
- a synthesis unit for conversion of the synthesis gas for synthesis of methanol or other oxygenated hydrocarbons, or for synthesis of synthetic fuel;
- means for injecting gas into the reservoir;
- means for transferring nitrogen from the air separation unit to the means for injecting gas;
- and
- means for transferring at least a part of a waste gas from the synthesis unit to the means for injecting gas.
A plant for providing gas for downhole injection for pressure support in an oil reservoir for recovery of hydrocarbons and production of methanol, dimethyl ether and/or other oxygenated hydrocarbons or for production of higher hydrocarbons from natural gas, comprising:
- an air separation unit configured to produce an oxygen-rich fraction;
- a reformer configured to convert a mixture of natural gas and oxygen from the air separation unit into a synthesis gas comprising mainly H2, CO, CO2 and lower amounts of methane;
- a synthesis unit configured to convert the synthesis gas for synthesis of methanol or other oxygenated hydrocarbons, or for synthesis of synthetic fuel;
- a first line in communication with the synthesis unit and configured to withdraw a waste gas therefrom for transfer to a unit for injection;
- and
- a second line in communication with the air separation unit and configured to transfer nitrogen from the air separation unit to the unit for injection.
Dependencies are inferred from the claim text.