Carbon dioxide fractionalization process

Abstract

A process comprising receiving a hydrocarbon feed stream comprising carbon dioxide, separating the hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream, separating the light hydrocarbon stream into a carbon dioxide-rich stream and a carbon dioxide-lean stream, and feeding the carbon dioxide-lean stream into a hydrocarbon sweetening process, thereby increasing the processing capacity of the hydrocarbon sweetening process compared to the processing capacity of the hydrocarbon sweetening process when fed the hydrocarbon feed stream. Included is an apparatus comprising a first separation unit that receives a hydrocarbon feed stream containing carbon dioxide and produces a heavy hydrocarbon stream and a light hydrocarbon stream, and a second separation unit that receives the light hydrocarbon stream and produces a carbon dioxide-rich stream and a carbon dioxide-lean stream, wherein the apparatus is configured to feed the carbon dioxide-lean stream to a physical solvent, membrane, or carbon dioxide recovery process.

What is claimed is: 
     
       1. A process comprising:
 receiving a hydrocarbon feed stream comprising carbon dioxide; 
 separating the hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream; 
 separating the light hydrocarbon stream into a carbon dioxide-rich stream and a carbon dioxide-lean stream; and 
 exchanging heat between the hydrocarbon feed stream and the carbon dioxide-lean stream; 
 feeding the carbon dioxide-lean stream into a hydrocarbon sweetening process, thereby increasing the processing capacity of the hydrocarbon sweetening process compared to the processing capacity of the hydrocarbon sweetening processwhen fed the hydrocarbon feed stream.; and 
 cooling the light hydrocarbon stream with the carbon dioxide-lean stream. 
 
     
     
       2. The process of  claim 1  wherein the hydrocarbon sweetening process comprises:
 absorbing at least some of the carbon dioxide from the carbon dioxide-lean stream with a solvent; 
 separating the solvent from the carbon dioxide-lean stream; and 
 releasing at least some of the carbon dioxide from the solvent by lowering the pressure of the solvent. 
 
     
     
       3. The process of  claim 1  wherein the hydrocarbon sweetening process comprises: separating at least some of the carbon dioxide from the carbon dioxide-lean stream using a membrane. 
     
     
       4. The process of  claim 1  wherein the hydrocarbon sweetening process comprises:
 absorbing at least some of the carbon dioxide from the carbon dioxide-lean stream with a solvent; 
 separating a methane-rich stream from the solvent; 
 separating an ethane-rich stream from the solvent; and 
 separating a heavy hydrocarbon stream from the solvent. 
 
     
     
       5. The process of  claim 1  wherein the hydrocarbon feed stream contains from about 30 percent to about 80 percent carbon dioxide. 
     
     
       6. The process of  claim 1  wherein the carbon dioxide-lean stream contains less than about 60 percent carbon dioxide and less than about 5 percent C 3+ . 
     
     
       7. The process of  claim 1  wherein the carbon dioxide-lean stream contains at least about 95 percent of a combination of methane and carbon dioxide. 
     
     
       8. The process of  claim 1  wherein the heavy hydrocarbon stream contains at least about 90 percent C 3+ . 
     
     
       9. The process of  claim 1  wherein the carbon dioxide-rich stream contains at least about 95 percent carbon dioxide. 
     
     
       10. The process of  claim 1  further comprising: transferring the carbon dioxide-rich stream to a pipeline for injection into a subterranean formation. 
     
     
       11. The process of  claim 1  wherein the increase in processing capacity of the hydrocarbon sweetening process is directly proportional to the decrease in carbon dioxide concentration between the hydrocarbon feed stream and the carbon dioxide-lean stream, and the decrease in flow rate between the hydrocarbon feed stream and the carbon dioxide-lean stream. 
     
     
       12. A process comprising:
 receiving a hydrocarbon feed stream comprising carbon dioxide;   cooling the hydrocarbon feed stream using a carbon dioxide-lean stream;   separating the cooled hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream;   compressing the light hydrocarbon stream;   cooling the compressed light hydrocarbon stream using the carbon dioxide-lean stream;   separating the compressed light hydrocarbon stream into a carbon dioxide-rich stream and the carbon dioxide-lean stream; and   removing at least some of the carbon dioxide in the carbon dioxide-lean stream using a hydrocarbon sweetening process.   
     
     
       13. The process of  claim 12  further comprising: separating the heavy hydrocarbon stream into an acid gas stream and a heavy hydrocarbon stream. 
     
     
       14. The process of  claim 12  wherein separating the cooled hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream comprises:
 separating the cooled hydrocarbon feed stream into a light fraction and a heavy fraction; 
 separating the heavy fraction into the light hydrocarbon stream and the heavy hydrocarbon stream; and 
 combining the light fraction with the light hydrocarbon stream. 
 
     
     
       15. The process of  claim 12  wherein the hydrocarbon sweetening process is a physical solvent process, a membrane process, or a carbon dioxide recovery process. 
     
     
       16. The process of claim 1 wherein exchanging heat between the hydrocarbon feed stream and the carbon dioxide-lean stream comprises cooling the hydrocarbon feed stream using the carbon dioxide-lean stream. 
     
     
       17. A process comprising:
 receiving a hydrocarbon feed stream comprising carbon dioxide;   separating the hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream;   separating the light hydrocarbon stream into a carbon dioxide-rich stream and a carbon dioxide-lean stream;   cooling the light hydrocarbon stream using the carbon-dioxide lean stream; and   feeding the carbon dioxide lean stream into a hydrocarbon sweetening process, thereby increasing the processing capacity of the hydrocarbon sweetening process when fed the hydrocarbon feed stream.   
     
     
       18. The process of claim 17 wherein the at least one stream cooled using the carbon-dioxide lean stream comprises the hydrocarbon feed stream. 
     
     
       19. A process comprising:
 receiving a hydrocarbon feed stream comprising carbon dioxide;   separating the hydrocarbon feed stream into a light hydrocarbon stream and a heavy hydrocarbon stream;   separating the light hydrocarbon stream into a carbon dioxide-rich stream and a carbon dioxide-lean stream;   cooling the light hydrocarbon stream with the carbon dioxide-lean stream;   further processing the heavy hydrocarbon stream;   feeding the carbon-dioxide-rich stream to further processing including at least one heat exchanger; and   feeding the carbon dioxide-lean stream into a hydrocarbon sweetening process comprising a SELEXOL plant, thereby increasing the processing capacity of the hydrocarbon sweetening process when fed the hydrocarbon feed stream.   
     
     
       20. The process of claim 19 wherein further processing of the heavy hydrocarbon stream comprises using a separator. 
     
     
       21. The process of claim 19 wherein further processing of the heavy hydrocarbon stream comprises using a heat exchanger. 
     
     
       22. The process of claim 19 further comprising the step of infecting carbon dioxide into a subterranean formation.