Hanger seal assembly

1. A tubing or casing hanger seal assembly comprising:

an actuation sleeve to be mounted on a tubing hanger;

a shoulder member to be mounted on the tubing hanger;

a seal assembly disposed between the actuation sleeve and the shoulder member, the seal assembly comprising:

a first set of seals engaged at a tapered interface; and

a second set of seals engaged at a tapered interface;

wherein, for each set of seals, a first radial plane across the set of seals and the tapered interface includes a radial sectional area of a first seal greater than a radial sectional area of a second seal, and a second radial plane across the set of seals and the tapered interface includes a radial sectional area of the second seal greater than a radial sectional area of the first seal.

2. The seal assembly of claim 1 wherein the tapered interfaces are disposed in the same direction.

3. The seal assembly of claim 1 wherein the tapered interfaces are parallel.

4. The seal assembly of claim 1 wherein the actuation sleeve is actuatable to energize the first and second sets of seals in a single setting motion.

5. The seal assembly of claim 1 wherein a load pathway extends from the actuation sleeve to the first set of seals, from the first set of seals directly to the second set of seals, and from the second set of seals to the shoulder member.

6. The seal assembly of claim 1 further comprising a pin coupled between a seal of the first set of seals and a seal of the second set of seals.

7. The seal assembly of claim 6 further comprising a support leg engaged between another seal of the first set of seals and another seal of the second set of seals.

8. The seal assembly of claim 1 wherein the shoulder member includes tapered shoulders to engage the second set of seals.

9. The seal assembly of claim 1 wherein the first set of seals is in direct contact with the second set of seals.

10. The seal assembly of claim 1 further comprising:

a tubing hanger; and

a hanger receptacle in a wellhead that receives the tubing hanger;

wherein the actuation sleeve, the shoulder member, and the seal assembly are disposed on the tubing hanger to capture the seal assembly between the tubing hanger and the hanger receptacle.

11. The seal assembly of claim 1 wherein:

the first set of seals comprises a first seal in contact with a second seal at the first tapered interface;

the second set of seals comprises a third seal in contact with a fourth seal at the second tapered interface;

the first radial plane across the first seal, the second seal and the first tapered interface includes the radial sectional area of the first seal greater than the radial sectional area of the second seal;

the second radial plane across the first seal, the second seal and the first tapered interface includes the radial sectional area of the second seal greater than the radial sectional area of the first seal;

the first radial plane across the third seal, the fourth seal and the second tapered interface includes the radial sectional area of the third seal greater than the radial sectional area of the fourth seal; and

the second radial plane across the third seal, the fourth seal and the second tapered interface includes the radial sectional area of the fourth seal greater than the radial sectional area of the third seal.

12. A tubing or casing hanger seal assembly comprising:

an actuation sleeve to be mounted on a tubing hanger and to provide a setting motion;

a shoulder member to be mounted on the tubing hanger;

a seal assembly disposed between the actuation sleeve and the shoulder member, the seal assembly comprising:

a first set of seals engaged at a tapered interface; and

a second set of seals engaged at a tapered interface;

wherein the first set of seals is coupled to the second set of seals such that the first and second sets of seals are energized by the same setting motion of the actuation sleeve.

13. The seal assembly of claim 12 further comprising a seal engagement interface disposed between the first and second sets of seals to directly transfer the setting motion from the first set of seals to the second set of seals.

14. The seal assembly of claim 12 further comprising a support member coupled between the first and second sets of seals.

15. The seal assembly of claim 12 further comprising a load pathway extending from the first set of seals through the second set of seals.

16. A method of actuating a tubing or casing hanger seal assembly comprising:

lowering a tool, sleeve, and seal assembly into a wellhead;

receiving the tool, sleeve, and seal assembly in a hanger receptacle in the wellhead;

actuating the tool to move the sleeve; and

energizing a first set of seals and a second set of seals in the seal assembly with the same sleeve movement.

17. The method of claim 16 wherein the first set of seals is an upper set of seals adjacent the sleeve, and the second set of seals is a lower set of seals disposed below the upper seals.

18. The method of claim 17 wherein the lower seals are energized before, or at the same time as, the upper seals.

19. The method of claim 17 further comprising energizing the lower seals against a tapered shoulder.

20. The method of claim 17 further comprising using a setting force to set the upper and lower seals, and wherein setting the lower seals uses less of the setting force than setting the upper seals.

21. The method of claim 16 wherein a seal of the first set of seals energizes a seal of the second set of seals across a seal engagement interface between the seals.

22. The method of claim 16 wherein each of the first and second sets of seals comprises a pair of seals with a tapered sliding interface therebetween, and sliding the seals in the same direction.

23. The method of claim 22 wherein a force applied from above and below each of the first and second sets of seals provides a sealing pressure enhancement above and below each of the first and second sets of seals.