Downhole tools, system and methods of using

1. A downhole a tool having an interior flowpath and an exterior comprising:

an inner sleeve;

a housing positioned outwardly of said inner sleeve, said housing and said inner sleeve partially defining a first space and a second space therebetween the first space and the second space in fluid isolation from the interior flowpath, from the exterior and from each other;

a shifting sleeve occupying a portion of said first space and a portion of said second space;

said housing further comprising a passageway for fluid communication from the interior flowpath of the housing to said space adjacent a first end of said shifting sleeve;

a fluid control device within said passageway, said fluid control device comprising a degradable member; and

wherein said shifting sleeve is selectively moveable from a first position to a second position, thereby moving the first end away from the passageway, in response to a predetermined fluid pressure in said passageway after at least partial degradation of said degradable member.

2. The downhole tool of claim 1 further comprising an input connector disposed on said housing, said input connector defining an opening to the passageway that enables fluid communication from the exterior of the housing to said first space.

3. The downhole tool of claim 2 wherein said fluid control device is disposed in a wall of said inner sleeve.

4. The downhole tool of claim 1 wherein said fluid control device is disposed in an inlet pressure chamber.

5. The downhole tool of claim 1 wherein said fluid control device is disposed in an upper pressure chamber.

6. The downhole tool of claim 1 further comprising a burst disk preventing fluid communication between the interior flowpath and the fluid control device.

7. A method for treating a well for oil, gas, or other hydrocarbons, said well containing a device having an interior flowpath and an exterior, the device comprising:

an outer housing, said housing having at least one port therethrough;

at least one shifting sleeve mounted within the housing, said shifting sleeve having a first position and a second position;

a first pressure chamber in fluid communication with said at least one shifting sleeve and a second pressure chamber in fluid communication with said at least one shifting sleeve, the first pressure chamber and the second pressure chamber in fluid isolation from the exterior, from the interior flowpath, and from each other;

a first fluid control device having a closed state and an open state, the first fluid control device preventing fluid communication between the pressure chamber and the interior flowpath when the first fluid control device is in the closed state and permitting fluid communication between the interior flowpath and the pressure chamber in the open state;

a second fluid control device having a closed state and an open state, the second fluid control device preventing fluid communication between the pressure chamber and the interior flowpath when the second fluid control device is in the closed state and permitting fluid communication between the interior flowpath and the pressure chamber in the open state;

wherein, the interior flowpath is not in fluid communication with the exterior when the shifting sleeve is in the first position, and the interior flowpath is in fluid communication with the exterior when the shifting sleeve is in the second position; and

the shifting sleeve is moveable from the first position to the second position in response to a predetermined interior flowpath pressure that is greater than the pressure chamber pressure; and

changing the first fluid control device from a closed state to an open state;

changing the second fluid control device from a closed state to an open state to allow fluid pressure from the interior flowpath to move the shifting sleeve from the first position to the second position.

8. The method of claim 7 wherein the first fluid control device comprises a burst disk and the second fluid control device comprises a degradable member, the method comprising rupturing the burst disk with hydraulic pressure from said interior flowpath, and degrading the degradable member in response to exposure to a selected fluid.

9. The method of claim 7 wherein the degradable member is exposed to the selected fluid after the first fluid control member is changed to an open state.

10. The method of claim 9 wherein the first fluid control member is a burst disk.

11. The method of claim 7 wherein at least one of the first fluid control device and second fluid control device are comprised of a magnesium alloy as the degradable material.

12. A method of preparing an open hole well for treating in at least one petroleum production zone formation in which a tubing string is inserted into the open hole well and cement is pumped through the production tubing into the open hole well, the method comprising: as the production tubing is inserted into the open hole well, providing at least one sliding valve to be positioned at a predetermined location along the production tubing;

said at least one sliding valve comprising an enclosure at least partially defining an interior flowpath of the sliding valve, the enclosure comprising an enclosure flowpath with a fluid control device comprising a degradable member therein; the enclosure comprising a first chamber and a second chamber in fluid isolation from each other, from the open hole and from the interior flowpath; at least one shifting member mounted within enclosure, the enclosure preventing fluid communication from the interior flowpath of the tubing to a first surface of the shifting member in the first chamber;

closing the end of the tubing string;

pressure testing the tubing string in the open hole well; then

changing the fluid control device from a closed state to an open state by degradation of the degradable member, thereby creating fluid communication between the interior flowpath and the first surface of the shifting member;

moving the shifting member from a closed position to an open position; and

flowing fluid from the interior of the sliding valve to the exterior of the sliding valve.

13. The method of claim 12 wherein the shifting member is moved from the closed position to the open position by application of fluid pressure against the first surface of the shifting member.

14. The method of claim 12 wherein the at least one sliding valve further comprises a burst disk, the method further comprising rupturing the burst disk by application of fluid pressure thereto.

15. The method of claim 14 wherein the burst disk isolates the fluid control device from fluid in the interior flowpath of the sliding valve.

16. The method of claim 12 wherein the fluid control device isolates the burst disk from fluid in the interior flowpath of the sliding valve.