Downhole production fluid fractionation system

1. A well completion, comprising:

a wellbore comprising a production tubing positioned within the wellbore, the production tubing having a surface end proximate a surface region and a subsurface end proximate a subsurface region, the production tubing conveying a portion of a production fluid from the subsurface region to the surface region; and

a fractionation system positioned within the wellbore on the subsurface end of the production tubing proximate to a production region of the wellbore, the fractionation system comprising:

a permeable hydrophobic media for preferentially conveying at least a first portion of the production fluid from the production region into the production tubing; and

a permeable oleophobic media for preferentially conveying at least a second portion of the production fluid from the production region into a second flow path, wherein the second flow path comprises an annulus between the production tubing and a production casing, and wherein the permeable oleophobic media covers a fluid inlet of the second flow path that is defined between the production tubing and a production packer that leads to the annulus;

wherein the permeable hydrophobic media and the permeable oleophobic media are in simultaneous hydraulic communication with the production region;

wherein the permeable hydrophobic media is manufactured to provide a relatively high effective permeability to oil, whereby the first portion of the production fluid comprises an oil-enriched stream that flows through the permeable hydrophobic media into the production tubing and is conveyed to the surface region; and

wherein the permeable oleophobic media is manufactured to provide a relatively high effective permeability to water, whereby the second portion of the production fluid comprises a water-enriched stream that flows through the permeable oleophobic media into the second flow path for disposing of the water-enriched stream.

2. The well completion of claim 1 , wherein the permeable hydrophobic media covers a plurality of perforations on the subsurface end of the production tubing, and wherein the oil-enriched stream flows through the permeable hydrophobic media and into the production tubing via the plurality of perforations.

3. The well completion of claim 1 , wherein the permeable hydrophobic media comprises at least one of a polytetrafluoroethylene (PTFE) material or a polyurethane material that has been manipulated such that it is substantially hydrophobic.

4. The well completion of claim 1 , wherein the permeable oleophobic media comprises a polyurethane material that has been manipulated such that it is substantially oleophobic.

5. The well completion of claim 1 , wherein the well completion comprises a dual concentric completion, and wherein the second flow path comprises a second production tubing that is concentric with the production tubing.

6. A method for separating production fluid in a subsurface region within a wellbore, comprising:

flowing a production fluid from a reservoir into a production region of a wellbore, wherein the production region is located within a subsurface region of the wellbore that is proximate to a subsurface end of a production tubing positioned within the wellbore;

conveying at least a first portion of the production fluid from the production region into the production tubing via a fractionation system, wherein the fractionation system is positioned within the wellbore on the subsurface end of the production tubing, wherein the fractionation system comprises a permeable hydrophobic media and a permeable oleophobic media that are in simultaneous hydraulic communication with the production region, and wherein the permeable hydrophobic media is manufactured to provide a relatively high effective permeability to oil, whereby the first portion of the production fluid comprises an oil-enriched stream that flows through the permeable hydrophobic media into the production tubing and is conveyed to a surface region of the wellbore; and

conveying at least a second portion of the production fluid from the production region into a second flow path via the fractionation system, wherein the second flow path comprises an annulus between the production tubing and a production casing, wherein the permeable oleophobic media covers a fluid inlet of the second flow path that is defined between the production tubing and a production packer that leads to the annulus, and wherein the permeable oleophobic media is manufactured to provide a relatively high effective permeability to water, whereby the second portion of the production fluid comprises a water-enriched stream that flows through the permeable oleophobic media into the second flow path for disposing of the water-enriched stream.

7. The method of claim 6 , comprising injecting the water-enriched stream into another subsurface region of the wellbore via the second flow path.

8. The method of claim 6 , comprising conveying the water-enriched stream to the surface region via the second flow path.

9. The method of claim 6 , wherein a thickness, a porosity, a permeability, and a wettability of the permeable hydrophobic media and the permeable oleophobic media are specifically tailored to separate the production fluid into the oil- enriched stream and the water-enriched stream within the subsurface.

10. The method of claim 6 , wherein the permeable hydrophobic media comprises at least one of a polytetrafluoroethylene (PTFE) material or a polyurethane material that has been manipulated such that it is substantially hydrophobic.

11. The method of claim 6 , wherein the permeable oleophobic media comprises a polyurethane material that has been manipulated such that it is substantially oleophobic.

12. The method of claim 6 , wherein disposing of the water-enriched stream via the second flow path comprises flowing the water-enriched stream into the annulus.

13. A fractionation system, comprising:

a permeable hydrophobic media; and

a permeable oleophobic media;

wherein the permeable hydrophobic media and the permeable oleophobic media are in simultaneous hydraulic communication with a fluid comprising oil and water;

wherein the permeable hydrophobic media is manufactured to provide a relatively high effective permeability to oil, whereby an oil-enriched stream flows through the permeable hydrophobic media into a first flow path; and

wherein the permeable oleophobic media is manufactured to provide a relatively high effective permeability to water, whereby a water-enriched stream flows through the permeable oleophobic media into a second flow path, wherein the second flow path comprises an annulus between a production tubing and a production casing of a wellbore, and wherein the permeable oleophobic media covers a fluid inlet of the second flow path that is defined between the production tubing and a production packer that leads to the annulus.

14. The fractionation system of claim 13 , wherein the fractionation system is implemented within a wellbore; the fluid comprises a production fluid; and the fractionation system is used to separate the production fluid into the oil-enriched stream and the water-enriched stream within a subsurface region of the wellbore.

15. The fractionation system of claim 13 , wherein a thickness, a porosity, a permeability, and a wettability of the permeable hydrophobic media and the permeable oleophobic media are specifically tailored to separate the fluid into the oil-enriched stream and the water-enriched stream.

16. The fractionation system of claim 13 , wherein the permeable hydrophobic media comprises at least one of a polytetrafluoroethylene (PTFE) material or a polyurethane material that has been manipulated such that it is substantially hydrophobic.

17. The fractionation system of claim 13 , wherein the permeable oleophobic media comprises a polyurethane material that has been manipulated such that it is substantially oleophobic.