LNG with ethane enrichment and reinjection gas as refrigerant
First Claim
1. A process for extracting natural gas liquids from a mixture of hydrocarbons produced from a reservoir, comprising:
- successively distilling the mixture to extract a methane overhead fraction from the mixture;
cooling and expanding the methane overhead fraction to produce liquefied natural gas and cold methane vapor;
recompressing at least a portion of the cold methane vapor; and
reinjecting at least part of the recompressed portion into the reservoir.
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Accused Products
Abstract
The present invention comprises a process for producing liquefied natural gas from the methane that is produced during natural gas liquids extraction. The process includes distilling the feed to extract methane, then cooling and expanding the methane to produce liquefied natural gas and cold methane vapor. The cold methane vapor is employed as a coolant to precool the feed and to cool the methane before expansion, and is then recompressed for reinjection into the well formation. The bottoms from the methane distillation may be further distilled to extract ethane, which may be cooled with the cold methane vapor and combined with the liquefied natural gas product. A portion of the recompressed methane may be diverted from the compressor train, cooled and expanded to produce additional liquefied natural gas and cold methane vapor.
63 Citations
28 Claims
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1. A process for extracting natural gas liquids from a mixture of hydrocarbons produced from a reservoir, comprising:
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successively distilling the mixture to extract a methane overhead fraction from the mixture; cooling and expanding the methane overhead fraction to produce liquefied natural gas and cold methane vapor; recompressing at least a portion of the cold methane vapor; and reinjecting at least part of the recompressed portion into the reservoir. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A process for producing liquefied natural gas from methane gas, wherein the process is carried out in the vicinity of a hydrocarbon producing reservoir having an associated natural gas liquids extraction apparatus comprising a demethanizer, the process comprising:
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supplying the methane gas for the process from an outlet of the demethanizer; cooling and expanding the methane gas; and separating liquefied natural gas from cold methane vapor. - View Dependent Claims (9, 10)
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11. An apparatus for producing liquefied natural gas from methane gas, comprising:
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means for cooling the methane gas; means for expanding the gas; means for separating liquefied natural gas from cold methane vapor; and a conduit to a methane gas inlet of the apparatus from a methane outlet of a demethanizer, the demethanizer being a component of a natural gas liquids extraction apparatus. - View Dependent Claims (12)
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13. An apparatus for simultaneously producing liquefied natural gas and extracting natural gas liquids from a mixture of hydrocarbons, the apparatus comprising:
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a demethanizer for distilling the mixture to produce a methane overhead fraction and a demethanizer bottoms fraction; a turbo-expander for expanding and cooling the methane; a separator whereby the methane is separated into liquefied natural gas and cold methane vapor; a compressor for recompressing the cold methane vapor; and a conduit connected between the compressor and a producing hydrocarbon reservoir such that at least a portion of the compressed methane vapor is injected into the producing hydrocarbon reservoir. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A process for producing liquefied natural gas from a mixture containing methane, ethane, and heavier hydrocarbons, comprising:
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separating the hydrocarbon mixture into a methane-rich fraction and a methane-lean fraction; cooling and expanding the methane-rich fraction; separating the expanded methane-rich fraction into methane-rich liquid and methane-rich vapor, at least a portion of the methane-rich vapor accomplishing the cooling of the methane-rich fraction by heat exchange therewith; separating at least a portion of the ethane from the methane-lean fraction; cooling the ethane by heat exchange with at least a portion of the methane-rich vapor; combining the methane-rich liquid with the cooled ethane to form a product mixture; expanding the product mixture; separating the product mixture into a liquid product and a gas product; and recompressing the methane-rich vapor and reinjecting at least a portion of the recompressed vapor into a producing hydrocarbon reservoir. - View Dependent Claims (21, 22)
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23. A process for producing ethane-enriched liquefied natural gas from a mixture of hydrocarbons, comprising:
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distilling the mixture successively to produce a condensate product and a plurality of overhead products, one of the overhead products comprising methane and another comprising ethane; liquefying at least a portion of the ethane overhead product and a first portion of the methane overhead product to form a liquefied natural gas product; cooling the hydrocarbon mixture, the methane overhead product, and the ethane overhead product by heat exchange with a second portion of the methane overhead product; and recompressing the second portion and injecting at least part of the second portion into a producing hydrocarbon reservoir. - View Dependent Claims (24, 25)
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26. A process for separating a mixture of hydrocarbons comprising:
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(a) cooling the mixture by heat exchange with a cold methane stream; (b) distilling the cooled mixture in a demethanizer column to produce methane-rich and methane-lean fractions; (c) distilling the methane-lean fraction in a deethanizer column to produce ethane-rich and ethane-lean fractions; (d) cooling the methane-rich and ethane-rich fractions by heat exchange with the cold methane stream; (e) expanding the cooled methane-rich fraction; (f) separating the expanded methane-rich fraction to produce a first methane-rich vapor and a first methane-rich liquid; (g) mixing the first methane-rich vapor with a second methane-rich vapor to form the cold methane stream; (h) compressing the cold methane stream to form a compressed methane stream; (i) injecting a portion of the compressed methane stream into a producing hydrocarbon reservoir; (j) cooling and expanding the remaining portion of the compressed methane stream to form an incremental methane stream; (k) separating the incremental methane stream to produce the second methane-rich vapor and a second methane-rich liquid; (l) mixing the first and second methane-rich liquids with the cooled ethane-rich fraction to produce a product mixture; (m) expanding the product mixture; (n) performing a vapor-liquid separation of the expanded product mixture to produce fuel gas and liquefied natural gas. - View Dependent Claims (27, 28)
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Specification