Pressure testing a wellhead

Abstract

A wellhead isolation tool includes a hydraulic assembly including a hydraulic line fluidly and a setting tool hydraulic ram that includes a mandrel head; a mandrel coupled to the hydraulic ram and including an uphole end and a downhole end configured to sting into a wellhead; a packing assembly including a bore that is configured to receive the mandrel; and a pack-off cup assembly coupled to the downhole end. The pack-off cup assembly includes a cup mounted on the mandrel and including a circular frustum that includes an uphole end defined by a first diameter; a downhole end opposite the uphole end and defined by a second diameter less than the first diameter; a bore that extends between the uphole end and the downhole end and is configured to receive a least a portion of the mandrel; and a radial surface between the uphole and downhole ends.

What is claimed is: 
     
         1 . A wellhead isolation tool, comprising:
 a hydraulic assembly comprising at least one hydraulic line fluidly and a setting tool hydraulic ram that comprises a mandrel head;   a mandrel coupled to the hydraulic ram, the mandrel comprising an uphole end coupled to the mandrel head and a downhole end configured to sting into a wellhead;   a packing assembly comprising a bore that is configured to receive the mandrel; and   a pack-off cup assembly coupled to the downhole end of the mandrel, the pack-off cup assembly comprising at least one cup mounted on the mandrel and comprising a circular frustum that includes:
 an uphole end defined by a first diameter; 
 a downhole end opposite the uphole end and defined by a second diameter less than the first diameter; 
 a bore that extends between the uphole end and the downhole end and is configured to receive a least a portion of the mandrel therethrough; and 
 a radial surface between the uphole and downhole ends. 
   
     
     
         2 . The wellhead isolation tool of  claim 1 , wherein the at least one cup is a first cup, the pack-off cup assembly comprising a second cup mounted on the mandrel and comprising a circular frustum that includes:
 an uphole end defined by a third diameter;   a downhole end opposite the uphole end and defined by a fourth diameter less than the third diameter;   a bore that extends between the uphole end and the downhole end and is configured to receive a least another portion of the mandrel therethrough; and   a radial surface between the uphole and downhole ends.   
     
     
         3 . The wellhead isolation tool of  claim 2 , wherein the first and third diameters are substantially equal, and the second and fourth diameters are substantially equal. 
     
     
         4 . The wellhead isolation tool of  claim 1 , wherein the at least one cup is formed of a sealing material configured to fluidly seal against a portion of the wellhead. 
     
     
         5 . The wellhead isolation tool of  claim 4 , wherein the sealing material comprises at least one elastomer. 
     
     
         6 . The wellhead isolation tool of  claim 1 , wherein the at least one cup is configured to compress in response to circulation of a pressurized fluid in an annulus between the mandrel and the wellhead when the mandrel is stung into the wellhead. 
     
     
         7 . The wellhead isolation tool of  claim 6 , wherein the pressurized fluid is at about 15,000 psi. 
     
     
         8 . The wellhead isolation tool of  claim 6 , wherein the mandrel comprises at least one seat, the at least one cup positioned on the mandrel such that the downhole end abuts the at least one seat. 
     
     
         9 . The wellhead isolation tool of  claim 8 , wherein the at least one cup is configured to compress against the at least one seat in response to circulation of the pressurized fluid in the annulus between the mandrel and the wellhead when the mandrel is stung into the wellhead. 
     
     
         10 . The wellhead isolation tool of  claim 1 , wherein the at least one cup is a first cup, the tool further comprising:
 a first seat positioned on the mandrel, the first cup positioned on the mandrel such that the downhole end of the first cup abuts the first seat;   a second cup mounted on the mandrel and comprising a circular frustum that includes:
 an uphole end defined by a third diameter; 
 a downhole end opposite the uphole end and defined by a fourth diameter less than the third diameter; 
 a bore that extends between the uphole end and the downhole end and is configured to receive a least another portion of the mandrel therethrough; and 
 a radial surface between the uphole and downhole ends; and 
   a second seat positioned on the mandrel and spaced apart from the first seat, the second cup positioned on the mandrel such that the downhole end of the second cup abuts the second seat.   
     
     
         11 . A method of pressure testing a wellhead, the method comprising:
 installing a wellhead isolation tool on a wellhead, the wellhead isolation tool comprising:
 a hydraulic assembly comprising at least one hydraulic line fluidly and a setting tool hydraulic ram that comprises a mandrel head; 
 a mandrel coupled to the hydraulic ram, the mandrel comprising an uphole end coupled to the mandrel head and a downhole end; 
 a packing assembly comprising a bore that is configured to receive the mandrel; and 
 a pack-off cup assembly coupled to the downhole end of the mandrel, the pack-off cup assembly comprising at least one cup mounted on the mandrel and comprising a circular frustum that includes:
 an uphole end defined by a first diameter; 
 a downhole end opposite the uphole end and defined by a second diameter less than the first diameter; 
 a bore that extends between the uphole end and the downhole end and is configured to receive a least a portion of the mandrel therethrough; and 
 a radial surface between the uphole and downhole ends; 
 
   operating the hydraulic assembly to insert the mandrel into the wellhead to sting the pack-off cup assembly into a wellbore tubing;   sealing a portion of an annulus between the mandrel and the wellbore tubing with the at least one cup;   circulating a pressurized fluid into the annulus between the mandrel and the wellbore tubing; and   pressure testing the wellhead with the pressurized fluid.   
     
     
         12 . The method of  claim 11 , wherein the at least one cup is a first cup, the pack-off cup assembly comprising a second cup mounted on the mandrel and comprising a circular frustum that includes an uphole end defined by a third diameter; a downhole end opposite the uphole end and defined by a fourth diameter less than the third diameter; a bore that extends between the uphole end and the downhole end and is configured to receive a least another portion of the mandrel therethrough; and a radial surface between the uphole and downhole ends, the method comprising:
 sealing another portion of the annulus between the mandrel and the wellbore tubing with the second cup.   
     
     
         13 . The method of  claim 11 , comprising compressing the at least one cup in response to circulating the pressurized fluid in the annulus between the mandrel and the wellbore tubing. 
     
     
         14 . The method of  claim 13 , wherein compressing the at least one cup comprises flattening the at least one cup to increase the first diameter to further seal the portion of the annulus between the mandrel and the wellbore tubing. 
     
     
         15 . The method of  claim 13 , wherein compressing the at least one cup comprises the mandrel comprises compressing the at least one cup against a seat positioned on the mandrel downhole of the at least one cup and abutting the downhole end of the at least one cup. 
     
     
         16 . The method of  claim 11 , wherein circulating the pressurized fluid comprises circulating the pressurized fluid at about 15,000 psi. 
     
     
         17 . The method of  claim 11 , comprising sealing at least a portion of the wellbore tubing downhole of the at least one cup against circulation of the pressurized fluid into the wellbore tubing with the at least one cup. 
     
     
         18 . The method of  claim 11 , comprising circulating the pressurized fluid into the wellhead through a hydraulic secondary wing valve that comprises an inlet oriented orthogonally to the annulus. 
     
     
         19 . The method of  claim 11 , wherein the at least one cup is a first cup, the pack-off cup assembly comprising a second cup mounted on the mandrel and comprising a circular frustum that includes an uphole end defined by a third diameter; a downhole end opposite the uphole end and defined by a fourth diameter less than the third diameter; a bore that extends between the uphole end and the downhole end and is configured to receive a least another portion of the mandrel therethrough; and a radial surface between the uphole and downhole ends, the method comprising:
 sealing the portion of the annulus by compressing the first cup against a first seat positioned on the mandrel downhole of the first cup and abutting the downhole end of the first cup; and   sealing another portion of the annulus by compressing the second cup against a second seat positioned on the mandrel downhole of the second cup and abutting the downhole end of the second cup.   
     
     
         20 . The method of  claim 19 , wherein the first and third diameters are substantially equal, and the second and fourth diameters are substantially equal. 
     
     
         21 . The method of  claim 19 , wherein installing the wellhead isolation tool on the wellhead comprises installing the wellhead isolation tool on the wellhead exclusive of the wellhead having a back pressure valve profile, a two way check valve profile, a test plug profile, or a tubing hanger landing profile. 
     
     
         22 . The method of  claim 19 , wherein installing the wellhead isolation tool on the wellhead comprises installing the wellhead isolation tool on the wellhead exclusive of a drilling rig, a coil tubing unit, a snubbing unit, or a workover rig.