Wellhead retrieval tool and method of retrieving a wellhead

Abstract

A wellhead retrieval tool comprising a body having a first portion and a second portion, the first portion carrying a release actuator assembly which is adapted to engage with a wellhead release mechanism of a housing and which is operable to actuate the wellhead release mechanism to release a wellhead from the housing, the second portion carrying a locking mechanism, which is operable to engage with a wellhead to lock the wellhead to the wellhead retrieval tool.

1 . A wellhead retrieval tool comprising a body having a first portion and a second portion, the first portion carrying a release actuator assembly which is adapted to engage with a wellhead release mechanism of a housing and
 which is operable to actuate the wellhead release mechanism to release a wellhead from the housing, the second portion carrying a locking mechanism which is operable to engage with a wellhead to lock the wellhead to the wellhead retrieval tool.   
     
     
         2 . A tool according to  claim 1  wherein the first portion of the tool body is generally tubular and has an open end which is configured to facilitate the positioning of the first portion of the tool body around the housing. 
     
     
         3 . A tool according to  claim 1  wherein the first portion of the tool body is provided with a frusto-conical portion which is configured such that the diameter of space enclosed by the first portion of the tool body decreases
 from the open end towards the second portion of the tool body. 
 
     
     
         4 . A tool according to  claim 1  wherein the tool body is tubular and encloses a main passage which extends through the first and second portions of the tool body, a first portion of the main passage being located within the first portion of the body and a second portion of the main passage
 being located within the second portion of the body. 
 
     
     
         5 . A tool according to  claim 4  wherein tool further comprises an end cap which is provided on the second portion of the tool body to at least partially close the second end of the main passage. 
     
     
         6 . A tool according to  claim 1  wherein the tool is provided with a
 connector which is mounted on an end of the tool body adjacent the second portion of the tool body. 
 
     
     
         7 . A tool according to  claim 5  wherein the connector is mounted on the end cap. 
     
     
         8 . A wellhead system comprising a tool according to  claim 1  and a
 wellhead assembly comprising a housing mounted at an end of a wellbore, a wellhead mounted in the housing, the tool being mounted on the wellhead assembly with the first portion of the tool around the housing and the second portion of the tool engaging with the wellhead. 
 
     
     
         9 . A wellhead system according to  claim 8  wherein the first portion of the body of the tool is tubular, the housing being located in the space enclosed by the first portion of the main passage 
     
     
         10 . A wellhead system according to  claim 8  wherein the second portion of the body is located in the wellhead. 
     
     
         11 . A wellhead system according to  claim 8  wherein the body of the tool is tubular and has a main passage which extends through the first and second portions of the tool body, a first portion of the main passage being located within the first portion of the body and a second portion of the main passage being located within the second portion of the body, housing being located in the first portion of the main passage and the wellhead being located in the second portion of the main passage. 
     
     
         12 . A wellhead system according to  claim 8  wherein the system further comprises a tubular landing string which is secured to the second portion of the tool body. 
     
     
         13 . A wellhead system according to  claim 8  wherein the housing has a tubular body which encloses a generally cylindrical space, the wellhead extending into the generally cylindrical space. 
     
     
         14 . A wellhead system according to  claim 8  wherein, the wellhead is provided with a wellhead locking element which is movable to lock the wellhead in the housing. 
     
     
         15 . A method of retrieving a wellhead mounted in a housing at an end of a wellbore, the wellhead being locked to the housing by means of a locking mechanism, the method comprising mounted a tool according to  claim 1  on a string or wire, lowering the string/wire towards the wellhead so that the first portion of the tool engages with the housing and the second portion of the tool engages with an end of the wellhead, operating the release actuator assembly to actuate the locking mechanism of the
 housing and to unlock the wellhead from the housing, operating the locking mechanism to lock the wellhead to the second portion of the tool, and lifting the string/wire and tool with the wellhead secured thereto to remove the wellhead from the housing.