Flow Tube

Abstract

A flow tube for a control head for an apparatus ( 1 ) for forming a liquid seal around a conduit, cable or wire for intervention into a well, the flow tube comprising a flexible body ( 16 ) capable of stretching to accommodate localised variations in the external diameter of the conduit, cable or wire while maintaining a close contact with the external surface of the conduit, cable or wire.

What is claimed is: 
     
         1 . A flow tube for a control head for an apparatus for forming a liquid seal around a conduit, cable or wire for intervention into a well, the flow tube comprising a flexible body capable of stretching to accommodate localised variations in the external diameter of the conduit, cable or wire while maintaining a close contact with the external surface of the conduit, cable or wire. 
     
     
         2 . A flow tube according to  claim 1 , wherein the flexible body comprises one or more sections. 
     
     
         3 . A flow tube according to  claim 2 , wherein each section comprises a substantially T-shaped member having a longitudinal portion and a radial portion which extends perpendicular to the longitudinal section and is formed at one end of the longitudinal section. 
     
     
         4 . A flow tube according to  claim 1 , wherein the flexible body of the flow tube comprises a plastics material. 
     
     
         5 . A flow tube according to  claim 4 , wherein the flexible body comprises polytetrafluoroethylene. 
     
     
         6 . A flow tube according to  claim 1 , wherein the flexible body comprises a metallic coating. 
     
     
         7 . A flow tube according to  claim 6 , wherein the metallic coating comprises bronze or carbon. 
     
     
         8 . A control head for an apparatus for forming a liquid seal around a conduit, cable or wire for intervention into a well, the control head comprising a flow tube according to  claim 1 . 
     
     
         9 . A control head according to  claim 8 , further comprising a housing, the housing having a bore extending from one end to the other through the housing, the flow tube providing a pathway for a conduit, cable or wire through the housing, the control head further comprising grease ports for pumping grease into the flow tube to provide a grease seal between the outer surface of the wire and the inner surface of the flow tube to allow the conduit, cable or wire to move longitudinally within the flow tube. 
     
     
         10 . A control head according to  claim 9 , further comprising one or more bushings mounted in the housing, the bushing(s) supporting the flow tube and mounting the flow tube in the housing. 
     
     
         11 . A control head according to  claim 10 , wherein the or each bushing has a circumferential groove in the outer surface. 
     
     
         12 . A control head according to  claim 11 , wherein a sealing means is mounted in the groove of the bushing to provide a seal between the outer surface of the bushing and the inner surface of the bore of the housing. 
     
     
         13 . A control head according to  claim 9 , wherein the housing comprises steel. 
     
     
         14 . A liquid seal stuffing box comprising a control head according to  claim 9 . 
     
     
         15 . A method of providing a grease seal around a conduit, cable or wire deployed into a well for operations including intervention and formation evaluation operations, the method comprising the steps of deploying a control head according to  claim 9  on pressure control equipment on the well, passing a conduit, cable or wire through the flow tube within the bore of the housing of the control head, the flow tube providing a close fit to the outer diameter of the conduit, cable or wire and accommodating any localised variations in outer diameter of the conduit, cable or wire and pumping grease into the flow tube to provide a grease seal between the outer surface of the cable, cable or wire and the inner surface of the flow tube to allow the conduit, cable or wire to move backwards and forwards through the flow tube.