Wellhead hanger gripping system and method

Abstract

A method for assessing grip of an elastically deformed wellhead housing on a wellhead hanger is provided. In one embodiment, a method includes actuating a wellhead clamp to elastically deform a wellhead housing to grip a wellhead hanger disposed inside the wellhead housing. The method also includes assessing the grip on the wellhead hanger, after the actuating of the wellhead clamp, based on a change in a wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp. Additional systems, devices, and methods are also disclosed.

1 . A method including:
 actuating a wellhead clamp to elastically deform a wellhead housing to grip a wellhead hanger disposed inside the wellhead housing; and   after the actuating of the wellhead clamp, assessing the grip on the wellhead hanger based on a change in a wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp.   
     
     
         2 . The method of  claim 1 , wherein the wall of the wellhead housing includes a hole surrounding a core in the wall of the wellhead housing such that the core is positioned within the hole, and wherein assessing the grip on the wellhead hanger based on the change in the wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp includes detecting protrusion of the core from the hole or retraction of the core into the hole. 
     
     
         3 . The method of  claim 2 , wherein detecting protrusion of the core from the hole or retraction of the core into the hole includes measuring an amount of protrusion or retraction of the core via a capacitive sensor. 
     
     
         4 . The method of  claim 1 , wherein assessing the grip on the wellhead hanger based on the change in the wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp includes assessing the grip on the wellhead hanger based on a change in a thickness of the wall of the wellhead housing. 
     
     
         5 . The method of  claim 4 , wherein assessing the grip on the wellhead hanger based on the change in the thickness of the wall of the wellhead housing includes measuring the thickness of the wall of the wellhead housing. 
     
     
         6 . The method of  claim 5 , wherein measuring the thickness of the wall of the wellhead housing includes measuring the thickness of the wall of the wellhead housing with an ultrasonic meter. 
     
     
         7 . The method of  claim 4 , wherein assessing the grip on the wellhead hanger based on the change in the thickness of the wall of the wellhead housing includes measuring a depth of a hole in the wall of the wellhead housing. 
     
     
         8 . The method of  claim 1 , wherein assessing the grip on the wellhead hanger based on the change in the wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp includes assessing the grip on the wellhead hanger based on strain measured following the actuating of the wellhead clamp. 
     
     
         9 . The method of  claim 8 , wherein assessing the grip on the wellhead hanger based on strain measured following the actuating of the wellhead clamp includes assessing the grip on the wellhead hanger based on strain measured on at least one of an outer surface of the wall, an inner surface of the wall, or the wellhead hanger. 
     
     
         10 . The method of  claim 1 , wherein assessing the grip on the wellhead hanger based on the change in the wall of the wellhead housing elastically deformed by the actuating of the wellhead clamp includes detecting a change in a state of an external visual indicator mounted on the wall of the wellhead housing. 
     
     
         11 . The method of  claim 1 , wherein actuating the wellhead clamp to elastically deform the wellhead housing to grip the wellhead hanger disposed inside the wellhead housing includes actuating the wellhead clamp to elastically deform the wellhead housing such that an inner surface of the wellhead housing bears directly against and grips the wellhead hanger disposed inside the wellhead housing. 
     
     
         12 . An apparatus comprising:
 a wellhead housing including a hollow body that has a wall surrounding a central bore through the hollow body, wherein the wall surrounding the central bore includes a measurement hole extending into the wall from an exterior surface of the wall, the measurement hole does not extend from the exterior surface of the wall to the central bore, and the measurement hole is configured to enable assessment of gripping integrity of the wall against a wellhead hanger within the central bore when the wellhead hanger is disposed within the central bore and the wellhead housing is elastically deformed by a wellhead clamp.   
     
     
         13 . The apparatus of  claim 12 , wherein the wall includes a measurement core within the measurement hole. 
     
     
         14 . The apparatus of  claim 13 , comprising a capacitive sensor to detect deflection of an outer surface of the measurement core with respect to an outer surface of the wall separated by the measurement hole from the outer surface of the measurement core. 
     
     
         15 . The apparatus of  claim 12 , comprising a depth gauge to measure a depth of the measurement hole. 
     
     
         16 . The apparatus of  claim 12 , comprising a bolt protruding outwardly from the measurement hole and a cap installed on an end of the bolt such that the cap is either free to rotate about the end of the bolt or is fixedly held by the bolt against an outer surface of the wall depending on an amount of elastic deformation of the wellhead housing by the wellhead clamp. 
     
     
         17 . The apparatus of  claim 12 , comprising the clamp and the wellhead hanger. 
     
     
         18 . An apparatus comprising:
 a wellhead housing including a hollow body that has a wall surrounding a central bore through the hollow body;   a wellhead clamp configured to elastically deform the wall of the wellhead housing to securely grip a wellhead hanger positioned within the central bore of the hollow body; and   a grip strength measurement device to assess gripping integrity of the wall against the wellhead hanger within the central bore of the hollow body when the wellhead hanger is disposed within the central bore and the wellhead housing is elastically deformed by the wellhead clamp.   
     
     
         19 . The apparatus of  claim 18 , wherein the grip strength measurement device includes an ultrasonic meter to measure a thickness of the wall. 
     
     
         20 . The apparatus of  claim 18 , wherein the grip strength measurement device includes a strain gauge.