Assembly

Abstract

A transport assembly comprising: an attachment member attachable to a downhole tool; normally two rotatable members, connected to the attachment member, the rotatable members being arranged to rotate around their main longitudinal axis; a plurality of engaging members attached to each rotatable member and extending radially outwards therefrom with respect to the main longitudinal axis; the engaging members being helically arranged around the rotatable members. The transport assembly can thus be driven into a well in a ‘corkscrew’ type manner. Embodiments include a jarring mechanism which may be reset downhole and can jar attached tools in either direction.

1 . A transport assembly comprising:
 an attachment member attachable to a downhole tool;   a rotatable member, connected to the attachment member, the rotatable member being arranged to rotate around its main longitudinal axis;   a plurality of engaging members attached to the rotatable member and extending radially outwards therefrom with respect to the main longitudinal axis; the engaging members being helically arranged around the rotatable member.   
     
     
         2 . A transport assembly as claimed in  claim 1 , wherein the rotatable member is a first rotatable member and there is a second rotatable member; the first and second rotatable members each having a helically arranged series of engaging members. 
     
     
         3 . A transport assembly as claimed in  claim 2 , wherein the helical arrangements of the engaging members define rotational patterns having rotational directions, the directions being opposite each other, one being clockwise and the other being anti-clockwise. 
     
     
         4 . A transport assembly as claimed in  claim 2 , wherein the first and second rotatable members are independently operable. 
     
     
         5 . A transport assembly as claimed in  claim 1 , wherein the engaging members are roller members which are arranged to rotate. 
     
     
         6 . A transport assembly as claimed in  claim 5 , wherein the roller members rotate around an axis perpendicular to the axis of rotation of the rotatable member. 
     
     
         7 . A transport assembly as claimed in  claim 5 , wherein each roller member is independently rotatable. 
     
     
         8 . A transport assembly as claimed in  claim 1 , comprising at least one motor to drive the rotatable member. 
     
     
         9 . A transport assembly as claimed in  claim 1 , comprising a jarring mechanism. 
     
     
         10 . A transport assembly as claimed in  claim 9 , wherein the jarring mechanism is provided between two rotatable members and is activated by rotation of the rotatable members with respect to each other. 
     
     
         11 . A transport assembly as claimed in  claim 1 , wherein the engaging members are attached to the surface of the rotatable member. 
     
     
         12 . A transport assembly as claimed in  claim 1 , wherein at least one engaging member is attached to the rotatable body via an arm linkage; the engaging member and arm linkage together forming a hub assembly. 
     
     
         13 . A transport assembly as claimed in  claim 12 , wherein the arm linkage is pivotally mounted on the rotatable member and pivotally connected to one of the engaging members. 
     
     
         14 . A transport assembly as claimed in  claim 12 , wherein there is a plurality of hub assemblies each comprising at least one engaging member and at least one arm linkage, the arm linkage mounted on the rotatable member. 
     
     
         15 . A transport assembly as claimed in  claim 12 , wherein at least one hub assembly has a second arm linkage mounted to the rotatable member and connected to the same engaging member of that hub assembly. 
     
     
         16 . A transport assembly as claimed in  claim 12 , wherein the first and second arm linkages of the or each hub assembly pivot in the same plane as each other and extend on the same side of the rotatable member. 
     
     
         17 . A transport assembly as claimed in  claim 12 , wherein the rotatable member is provided as two rings which are independently axially movable with respect to each other. 
     
     
         18 . A transport assembly as claimed in  claim 17 , wherein the first arm linkage of the or each hub assembly is mounted to the first ring of the rotatable member and the second arm portion of the or each hub assembly is mounted to the second ring of the rotatable member. 
     
     
         19 . A transport assembly as claimed in  claim 12 , comprising at least one of a proactive and a reactive mechanism to move the engaging member from a relatively retracted radial position to an extended radial position. 
     
     
         20 . A transport assembly as claimed in  claim 12 , wherein a resilient element is mounted between the rotatable member and the attachment member around an outer side of the rotatable member. 
     
     
         21 . A transport assembly as claimed in  claim 1 , comprising at least one retaining member disposed between the engaging members and the rotatable member operable to resist separation of the engaging members from the rotatable member. 
     
     
         22 . A transport assembly as claimed in  claim 21 , wherein the retaining member is substantially spherical and arranged to both retain the engaging members on the rotatable member and reduce friction between the engaging members and the rotatable member.