Self-cleaning filter

1. A downhole assembly for use in a casing string comprising:

a filter body positionable within the casing string, the filter body having an open end and a closed end, the filter body including a plurality of perforations; and

a fan positionable within the filter body, the fan comprising:

a mount that extends along a length of the fan;

a blade coupled to and extending radially from the mount, the blade having a first end and a second end, wherein the second end is offset from the first end and wherein the blade is rotatable in response to a fluid flow from the first end of the blade to the second end of the blade; and

an outer edge of the blade for contacting an inner surface of the filter body.

2. The assembly of claim 1 , wherein the closed end of the filter body includes an opening for receiving an end of the mount.

3. The assembly of claim 1 , wherein the filter body is generally cylindrical shape.

4. The assembly of claim 1 , wherein the outer edge comprises a rubber material for wiping the inner surface of the filter body.

5. The assembly of claim 1 , wherein the outer edge of the blade comprises a plurality of fibers for sweeping the inner surface of the filter body.

6. The assembly of claim 1 , wherein the blade extends at least partially circumferentially around the mount.

7. The assembly of claim 1 , wherein the filter body is coupled to the inner surface of a casing string.

8. The assembly of claim 1 , wherein the filter body and the fan both comprise a drillable material.

9. A downhole assembly for use in a casing string comprising:

a fan positionable within a filter body having a plurality of perforations, the fan comprising:

a mount that extends along a length of the fan;

a blade coupled to and extending radially from the mount, the blade, the blade having a first end and a second end, wherein the second end is offset from the first end, and the blade having a width that corresponds to an inner radius of the filter body; and

an outer edge of the blade for contacting an inner surface of the filter body.

10. The assembly of claim 9 , wherein the filter body has an open end and a closed end.

11. The assembly of claim 9 , wherein the filter body is generally cylindrical in shape and includes a closed end having an opening for receiving the mount of the fan.

12. The assembly of claim 9 , wherein the filter body is coupled to the inner surface of a casing string.

13. The assembly of claim 9 , wherein the fan and the filter body both comprise a drillable material.

14. The assembly of claim 9 , wherein the filter body is generally conical in shape.

15. The assembly of claim 9 , wherein the plurality of perforations are slots.

16. A downhole assembly for use in a casing string comprising:

the casing string; and

a filter body coupled to the casing string, the filter body further comprising:

a closed end;

an open end for receiving a fan having a blade for brushing an inner surface of the filter body in response to a fluid flowing into the filter body; and

a plurality of perforations for permitting a fluid to flow through the filter body, the plurality of perforations sized to prevent a particle of debris within the fluid from passing through the filter body,

wherein the closed end includes an opening for receiving a portion of the fan.

17. The assembly of claim 16 , further comprising the fan, wherein the blade of the fan has a width that corresponds to a radius of the filter body.

18. The assembly of claim 16 , wherein the plurality of perforations are slots.

19. The assembly of claim 16 , further comprising the fan wherein the blade of the fan includes an outer edge of the blade that includes a rubber material for brushing the inner surface of the filter body in response to the fluid flowing into the filter body.