Frangible disk sub, method and system

1. A frangible disk sub comprising:

a housing;

a break mechanism disposed in the housing;

a carrier movably disposed in the housing;

a frangible disk mounted in the carrier and movable with the carrier into contact with the break mechanism; and

a release mechanism restraining movement of the carrier until a threshold load is exceeded, the release mechanism comprising a collet finger having a collet head and the collet finger including a shear tab extending radially from the collet finger.

2. The sub as claimed in claim 1 , wherein the break mechanism includes a member housing and a hard point member disposed therein, the hard point in member being aligned with the frangible disk.

3. The sub as claimed in claim 1 , wherein carrier is movably sealed to the housing.

4. The sub as claimed in claim 1 , wherein the disk is sealed to the carrier.

5. The sub as claimed in claim 1 , wherein the release mechanism comprises a collet.

6. The sub as claimed in claim 5 , wherein the release mechanism comprises a feature to engage the collet.

7. The sub as claimed in claim 6 , wherein the feature includes an angled face.

8. The sub as claimed in claim 6 , wherein the feature includes an orthogonal face.

9. The sub as claimed in claim 5 , wherein the collet releases by deflection at the threshold load.

10. A method for rupturing a frangible disk comprising:

exceeding a threshold load with on the sub as claimed in claim 1 ;

releasing the release mechanism;

moving the carrier and the frangible disk toward and into contact with the break mechanism; and

rupturing the frangible disk with the break mechanism.

11. The method as claimed in claim 10 wherein the releasing is deflecting a collet.

12. The method as claimed in claim 10 wherein the releasing is shearing the shear tab on the collet finger.

13. A method for rupturing a frangible disk comprising:

exceeding a threshold load with on the sob as claimed in claim 1 ;

releasing the release mechanism;

moving the carrier and the frangible disk toward and into contact with the break mechanism; and

rupturing the frangible disk with the break mechanism,

wherein the releasing is shearing a shear member of a ring secured by the member to one of the housing or the carrier.

14. A method for rupturing a frangible disk comprising:

exceeding a threshold load with on the sub as claimed in claim 1 ;

releasing the release mechanism,

moving the carrier and the frangible disk toward and into contact with the break mechanism; and

rupturing the frangible disk with the break mechanism,

wherein the releasing is parting a tensile ring.

15. A borehole system comprising:

a borehole in a subsurface formation;

a string in the borehole; and

a frangible disk sub as claimed in claim 1 disposed within or as a part of the string.

16. A frangible disk sub comprising:

a housing;

a break mechanism disposed in the housing;

a carrier movably disposed in the housing;

frangible disk mounted in the carrier and movable with the carrier into contact with the break mechanism; and

a release mechanism restraining movement of the carrier until a threshold load is exceeded wherein the release mechanism comprises a ring having a shoulder for engagement with a collet, the ring being secured to one of the housing or the carrier by a shear member.

17. The sub as claimed in claim 16 , wherein the shoulder includes a back angle.

18. A frangible disk sub comprising:

a housing;

a break mechanism disposed in the housing;

a carrier movably disposed in the housing;

a frangible disk mounted in the carrier and movable with the carrier into contact with the break mechanism; and

a release mechanism restraining movement of the carrier until a threshold load is exceeded wherein the release mechanism comprises a tensile ring secured to the housing and the carrier.

19. The sub as claimed in claim 18 , wherein the tensile ring is secured with a body lock ring.

20. The sub as claimed in claim 18 , wherein the tensile ring includes a tensile area.