GB1494301A - Adjustable suspension of well tubing - Google Patents

Abstract

1494301 Wells &c GRAY TOOL CO 20 April 1976 15934/76 Heading E1F A wellhead assembly 10 including a tubing head 14 and a tubing string 26 supported therefrom by a tubing hanger 30, has an adjustable ram assembly 34 for supporting the hanger 30 relative to the head 14, the ram head (40) being movable by positioning means to a first -position where it does not engage the hanger 30, a second position (Fig. 2B) where it comes into ratcheting engagement with the hanger 30, and a third position where it interferes with the hanger 30 to prevent relative vertical movement between the hanger 30 and the head 14. As shown the ram head is reciprocable in a bore 41 in the tubing head 14 and has teeth for cooperation with grooves in the hanger 30 to provide the ratcheting and interfering engagement. The positioning means comprises a rotatable shaft 59 having an enlarged threaded portion 66 for engagement with screw threads 68 of a plug 52 and having a head 60 located in an opening 61 in the ram head. Thus rotation of the shaft effects movement of the ram head into its first, second or third positions, and a lost motion connection is provided to allow ratcheting since the width A of the head 60 is less than the width B of the opening 61. The ram head is biased into engagement with the hanger 30 by a spring 49, and a rod (70) extends between the plug 52 and the ram head to prevent rotation of the ram head. Preferably the wellhead assembly 10 includes a lower tubing head 12 and an outer string 18, the inner string having a subsurface safety valve 27 attached thereto. In installing the valve 27, the ram heads are moved to their first position, the outer string 18 is fixed with respect to the lower head 12, the inner string 26 with valve 27 is installed to a predetermined depth, the valve 27 is latched with respect to the outer string 18, the ram heads are moved to their second position, the hanger 30 is tensioned and pulled upwardly with respect to the upper head 14 until a desired position is reached, and the ram heads are moved to their third position. A packoff assembly 77 may then be installed and plastics material can be injected through an injector 81 to effect packing of seals 80 to seal the annulus between the strings 18, 26. The method may be modified to allow the removal of tubing joints from the inner string 26 after tensioning, tubing pup joints and the hanger then being attached to the string to make it a desired length.