System and method for low-pressure well completion
View Patent ↗A low-pressure wellhead system with tubular heads and mandrels secured independently using threaded unions. A casing mandrel is secured to a wellhead by a first threaded union. Likewise, a tubing head spool is secured to the casing mandrel using a threaded union. A tubing hanger is also secured to the tubing head spool using a threaded union. An adapter flange may also be secured to the tubing hanger by a threaded union. Because this low-pressure wellhead is faster and easier to assemble and provides full bore access, there is less rig downtime, thus rendering the well completion process faster and more economical.
1. A wellhead system for extracting subterranean hydrocarbons from a low-pressure well, the wellhead system comprising:
a wellhead securing and suspending a surface casing of the low-pressure well;
a casing mandrel supported by the wellhead and secured to the wellhead by a spanner nut or hammer union, the casing mandrel securing and suspending a production casing in the low-pressure well;
a tubing head spool supported by the casing mandrel and threadedly secured to the casing mandrel by a spanner nut or a hammer union; and
a tubing hanger secured to the tubing head spool by a spanner nut or a hammer union, the tubing hanger securing and suspending a production tubing in the low-pressure well.
2. The wellhead system as claimed in claim 1 wherein the wellhead is supported in a conductor bowl of a conductor assembly of the low-pressure well.
3. The wellhead system as claimed in claim 1 wherein the casing mandrel is supported in a casing bowl of the wellhead.
4. The wellhead system as claimed in claim 3 wherein the tubing head spool is further secured to the casing mandrel by a pin thread that connects the tubing head spool to the casing mandrel.
5. The wellhead system as claimed in claim 4 wherein the tubing head spool further comprises annular grooves above the pin thread in which O-rings are seated for providing a fluid-tight seal between the tubing head spool and the casing mandrel.
6. The wellhead system as claimed in claim 1 wherein the tubing hanger further comprises annular grooves in which O-rings are seated to provide a fluid-tight seal between the tubing hanger and the tubing head spool.
7. The wellhead system as claimed in claim 6 further comprising an annular packing that is compressed between the tubing hanger and the tubing head spool beneath the spanner nut or the hammer union that secures the tubing hanger to the tubing head spool.
8. The wellhead system as claimed in claim 1 wherein a top end of the tubing hanger extends above a top end of the spanner nut or the hammer union that secures the tubing hanger to the tubing head spool.
9. The wellhead system as claimed in claim 8 wherein the top end of the tubing hanger that extends above the top end of the spanner nut or the hammer union that secures the tubing hanger to the tubing head spool comprises a tubing hanger pin thread.
10. The wellhead system as claimed in claim 9 further comprising an adapter flange supported by the top end of the tubing hanger.
11. The wellhead system as claimed in claim 10 wherein the adapter flange further comprises a top flange for supporting a flow-control device.
12. The wellhead system as claimed in claim 10 wherein the adapter flange is secured to the top end of the tubing hanger by the spanner nut or the hammer union that engages the tubing hanger pin thread.
13. The wellhead system as claimed in claim 11 wherein the adapter flange further comprises an adapter flange pin thread that engages a corresponding box thread in the tubing hanger to further secure the adapter flange to the tubing hanger.
14. The wellhead system as claimed in claim 12 wherein the adapter flange further comprises annular grooves above the adapter flange pin thread in which O-rings are seated to provide a fluid-tight seal between the adapter flange and the tubing hanger.
15. A low-pressure wellhead system comprising:
a first tubular head supported by a conductor assembly, the first tubular head securing and suspending a surface casing in a well bore;
a first mandrel supported by the first tubular head and secured to the first tubular head by a spanner nut or hammer union, the first mandrel securing and suspending a production casing in the well bore;
a second tubular head supported by the first mandrel and secured to the first mandrel by a spanner nut or hammer union; and
a second mandrel supported by the second tubular head and secured to the second tubular head by a spanner nut or a hammer union, the second mandrel securing and suspending a production tubing in the well bore.
16. The wellhead system as claimed in claim 15 wherein the second tubular head comprises a tubing head spool and the tubing head spool is further secured to the first mandrel by a pin thread on a bottom end of the tubing head spool.
17. The wellhead system as claimed in claim 15 further comprising an adapter flange supported by the second mandrel, the adapter flange permitting the connection of a flanged flow-control device to the wellhead system.
18. The wellhead system as claimed in claim 17 wherein the adapter flange is secured to the second mandrel by a spanner nut or a hammer union.
19. The wellhead system as claimed in claim 17 wherein the adapter flange is further secured to the second mandrel by a pin thread on a bottom end of the adapter flange that engages a corresponding box thread in the second mandrel.
20. A low-pressure wellhead system comprising:
an independent screwed wellhead supported in a conductor bowl of a conductor assembly, the independent screwed wellhead securing and suspending a surface casing in a well bore;
a casing mandrel supported in a casing bowl of the independent screwed wellhead and secured to the independent screwed wellhead by a spanner nut or a hammer union, the casing mandrel securing and suspending a production casing in the well bore;
a tubing head spool supported by the casing mandrel and secured to the casing mandrel by a spanner nut or a hammer union; and
a tubing hanger supported in a tubing bowl of the tubing head spool and secured to the tubing head spool by a spanner nut or a hammer union, the tubing hanger securing and suspending a production tubing in the well bore.