Method for oil recovery from an oil field
AssigneesStatoil ASA, Petrose (The Petroleum Oil & Gas Corporation of SA (Pty) Ltd)
InventorsGareth Shaw, Ola Olsvik, Erling Rytter, Jan Stetsen
Life of this patent
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Abstract
A method for increasing oil recovery from an oil reservoir in which method surplus gas streams from a plant for synthesis of higher hydrocarbons from natural gas is injected into the reservoir, is described. The surplus streams from the plant is the tailgas from the synthesis and optionally nitrogen from an air separation unit which delivers oxygen or oxygen enriched air to the plant for synthesis of higher hydrocarbons.
Claims14
A method for increasing oil recovery from an oil reservoir in which method gas is injected into the reservoir, comprising the steps of:
- separation of 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, CO2 and lower amounts of non-converted methane, water vapour and nitrogen,
- formation of higher hydrocarbons from the synthesis gas in a synthesis unit,
- withdrawing raw synthesis products and 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 recovering of hydrocarbons and production of oxygenated hydrocarbons or higher hydrocarbons from natural gas, comprising:
- an air separation unit (2) for production of an oxygen-rich fraction for supply to processes that require oxygen, and a nitrogen-rich fraction for injection;
- a reformer (8) for conversion of a mixture of natural gas, water and oxygen or oxygen enriched air from the air separation unit into a synthesis gas comprising mainly H2, CO, CO2 and small amounts of methane in addition to any inert gas, such as nitrogen;
- a synthesis unit (15, 56) for conversion of the synthesis gas for synthesis of higher hydrocarbons;
- means for injecting gas (6) 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 method for increasing oil recovery from an oil reservoir in which method gas is injected into the reservoir, comprising the steps of:
- supplying of compressed air,
- providing a natural gas stream and leading the natural gas stream and at least a part of the air stream to a reformer for conversion to synthesis gas mainly comprising N2, H2, CO, CO2 and lower amounts of non-converted methane, and water vapour,
- formation of higher hydrocarbons from the synthesis gas in a synthesis unit,
- withdrawing raw synthesis products and a nitrogen rich waste gas from the synthesis unit, and
- injecting at least a part of the nitrogen-rich 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 recovering of hydrocarbons and production of oxygenated hydrocarbons or higher hydrocarbons from natural gas, comprising:
- an air compression unit (24) for production of compressed air for supply to processes that require air;
- a reformer (8) for conversion of a mixture of natural gas, water and air from the air compression unit into a synthesis gas comprising mainly N2, H2, CO, CO2 and small amounts of methane;
- a synthesis unit (15, 56) for conversion of the synthesis gas for synthesis of higher hydrocarbons;
- means for injecting gas (6) into the reservoir;
- and
- means for transferring at least a part of the nitrogen rich waste gas from the synthesis unit to the means for injecting gas.
Dependencies are inferred from the claim text.