Tubing head spool with adapter bushing

1. An apparatus for connection to a wellhead, the apparatus comprising:

a tubing head spool having an inner circumferential surface, a first lateral end that forms a wellhead connection with the wellhead, and a second lateral end;

a tubing hanger adapter bushing with an outer circumferential surface and a tubing head interface, wherein the outer circumferential surface is sized to fit within the tubing head spool;

a first hang off mechanism having a hang off ring seat located circumferentially within the inner circumferential surface of the tubing head spool and a hang off ring disposed circumferentially around the outer circumferential surface of the tubing hanger adapter bushing;

a lock ring mechanism having a lock ring interface machined into the inner circumferential surface of the tubing head spool and a lock ring disposed circumferentially around the outer circumferential surface of the tubing hanger adapter bushing; and

an activation ring, having a smart ring and a plurality of first shear pins, disposed circumferentially around the outer circumferential surface of the tubing hanger adapter bushing, wherein the smart ring responds to a force that allows the activation ring to move in an upward direction, shearing the plurality of first shear pins, and pushing the hang off ring into the hang off ring seat.

2. The apparatus of claim 1 , further comprising:

a lock mandrel, having a lock ring profile, disposed circumferentially around the outer circumferential surface of the tubing hanger adapter bushing.

3. The apparatus of claim 2 ,

wherein the lock mandrel responds to a downward force to place the lock ring around the lock ring profile which places the lock ring into the lock ring interface of the tubing head spool.

4. The apparatus of claim 3 , further comprising:

an anti-back off ring disposed circumferentially around the outer circumferential surface of the tubing hanger adapter bushing.

5. The apparatus of claim 4 ,

wherein the anti-back off ring comprises a bump which interacts with thread profiles in response to an upward force and prevents upward movement of the tubing hanger adapter bushing within the tubing head spool.

6. A method comprising:

installing a tubing head spool onto a wellhead;

installing a blow out preventer onto the tubing head spool;

drilling a well by running downhole tools and at least one casing string through the tubing head spool;

running a tubing hanger adapter bushing through the blow out preventer and into the tubing head spool, wherein the tubing hanger adapter bushing comprises an activation ring and a hang off ring;

running a tubing string into the well; and

hanging off the tubing hanger adapter bushing in the tubing head spool by activating the activation ring to push the hang off ring into a hang off ring seat located in the tubing head spool.

7. The method of claim 6 , further comprising:

locking the tubing hanger adapter bushing in the tubing head spool using a lock ring mechanism.

8. The method of claim 7 ,

wherein locking the tubing hanger adapter bushing in the tubing head spool using a lock ring mechanism further comprises applying a downward force to shear a plurality of fourth shear pins to place a lock ring into a lock ring interface.