Tubing hanger vent

In a wellhead assembly having a christmas tree with an axial bore, a lateral production passage, and a tubing hanger landed in the bore of the tree, the tubing hanger having an axial bore and a lateral opening that aligns with the lateral production passage in the tree, the improvement comprising:

• a first retrievable plug landed in the bore of the tubing hanger above the lateral opening;
• an internal tree cap assembly landed in the bore of the tree above the tubing hanger, the tree cap assembly having an axial bore and a downward depending isolation sleeve which extends into the bore of the tubing hanger;
• a seal on the isolation sleeve which seals in the bore of the tubing hanger, creating a void between the first plug and the internal tree cap;
• a second retrievable plug landed in the bore of the tree cap assembly;
• a vent passage communicating with the void for expelling fluid trapped between the plugs when the tree cap assembly is landed in the bore of the tree;
• and
• a valve for opening and closing the vent passage.

A wellhead assembly, comprising in combination:

• a christmas tree having an axial bore and a lateral production passage;
• a tubing hanger landed in the bore of the tree and having a lateral opening that aligns with the lateral production passage in the tree and an axial bore;
• a first retrievable plug landed in the bore of the tubing hanger above the lateral opening;
• an internal tree cap landed in the bore of the tree above the tubing hanger, the tree cap having a downward depending isolation sleeve which extends sealingly into the bore of the tubing hanger creating a void between the tree cap and the first plug;
• a check valve in the tree cap in communication with the void and adapted to be held in an open position when the tree cap is landed in the bore of the tree so that fluid may be released from the void to avoid fluid lock.

In a wellhead assembly having a christmas tree with an axial bore, a lateral production passage, and a tubing hanger landed in the bore of the tree, the tubing hanger having an axial bore and a lateral opening that aligns with the lateral production passage in the tree, the improvement comprising:

• a first retrievable plug landed in the bore of the tubing hanger above the lateral opening;
• an internal tree cap assembly landed in the bore of the tree above the tubing hanger, the tree cap assembly having an axial bore and a downward depending isolation sleeve which extends into the bore of the tubing hanger;
• a seal on the isolation sleeve which seals in the bore of the tubing hanger, creating a void between the first plug and the internal tree cap;
• a second retrievable plug landed in the bore of the tree cap assembly;
• a vent passage leading through the tubing hanger between the isolation sleeve and the tubing hanger to an exterior of the tree for expelling fluid trapped between the plugs when the tree cap assembly is landed in the bore of the tree;
• and
• a valve for opening and closing the vent passage.

A method for avoiding fluid lock in a wellhead assembly, comprising:

• (a) providing a christmas tree having an axial bore and a lateral production passage;
• (b) landing a tubing hanger in the bore of the tree, the tubing hanger having a lateral opening that aligns with the lateral production passage in the tree and an axial bore;
• (c) landing a retrievable plug in the bore of the tubing hanger above the lateral opening;
• (d) landing an internal tree cap assembly in the bore of the tree above the tubing hanger, the tree cap assembly having a downward depending isolation sleeve which extends into the bore of the tubing hanger;
• (e) sealing the isolation sleeve with a seal in the bore of the tubing hanger, creating a void between the plug and the internal tree cap;
• and then
• (f) releasing fluid trapped in the void through a vent port for avoiding fluid lock in the void between the plug and the tree cap assembly when the tree cap assembly is landed in the bore of the tree.

A method for avoiding fluid lock in a wellhead assembly, comprising:

• (a) providing a christmas tree having an axial bore and a lateral production passage;
• (b) landing a tubing hanger in the bore of the tree, the tubing hanger having a lateral opening that aligns with the lateral production passage in the tree and an axial bore;
• (c) landing a first retrievable plug in the bore of the tubing hanger above the lateral opening;
• (d) landing an internal tree cap assembly in the bore of the tree above the tubing hanger, the tree cap assembly having a downward depending isolation sleeve which extends into the bore of the tubing hanger;
• (e) landing a second retrievable plug in the bore of the tree cap assembly;
• (f) sealing the isolation sleeve with a seal in the bore of the tubing hanger, creating a void between the plugs;
• and then
• (g) releasing fluid trapped in the void through a vent port for avoiding fluid lock in the void between the plugs when the tree cap assembly is landed in the bore of the tree.

A method for avoiding fluid lock in a wellhead assembly, comprising:

• (a) providing a christmas tree having an axial bore and a lateral production passage;
• (b) landing a tubing hanger in the bore of the tree, the tubing hanger having a lateral opening that aligns with the lateral production passage in the tree and an axial bore;
• (c) landing a retrievable plug in the bore of the tubing hanger above the lateral opening;
• (d) landing an internal tree cap assembly in the bore of the tree above the tubing hanger, the tree cap assembly having a downward depending isolation sleeve which extends into the bore of the tubing hanger;
• (e) sealing the isolation sleeve with a seal in the bore of the tubing hanger, creating a void between the plug and the internal tree cap;
• and
• (f) providing a check valve in the tree cap assembly for avoiding fluid lock in the void between the plug and the tree cap assembly when the tree cap assembly is landed in the bore of the tree;
• and then
• (g) opening the check valve so that fluid may be released from the void.