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US 5,628,366 AGranted
Protective arrangements for downhole tools
AssigneeNodeco Limited of International Base
InventorGeorge Telfer
Life of this patent
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AssigneeNodeco Limited of International Base
InventorGeorge Telfer
Estimating the term…
A protective arrangement or "junk bonnet" (30) for preventing debris entering a downhole tool assembly (14) employed in the drilling of a well. The junk bonnet (30) is in the form of an annular seal which fits around a tube (18) and inside a sleeve (24) which are relatively movable to operate a downhole tool assembly (14) of which they form part. The junk bonnet (30) is provided with sliding fluid seals (42, 44, 48, 50) which seal against the external surface (19) of the tube (18), and against the bore (25) of the sleeve (24). A longitudinal fluid passage (52) links opposite ends (54, 56) of the junk bonnet (30). The passage (52) is sealed in use by a plug (60) or other suitable valve. An annular volume ("C") below the junk bonnet (30), between the tube (18) and the sleeve (24), and above a seal (26) forming part of the downhole tool assembly (14) is filled through the passage (52) with hydraulic oil during setting-up and prior to closure of the passage (52) by the plug (60). This hydraulically locks the junk bonnet (30) in place on the downhole tool assembly (14), without reliance on any mechanical fastening, and yet free of susceptibility to being dislodged by normal operational movements of the downhole tool assembly (14). The upper end (56) of the junk bonnet (30) can be formed as a back-reamer, and an emergency release (72) can be incorporated.
A downhole tool assembly comprising a sleeve member (24), a tube member (18) axially movable with respect to and at least partially located within said sleeve member (24), a seal member (26) mounted within a lower end of said sleeve member (24) providing a sliding fluid seal to the exterior of said tube member (18) or to the exterior of a tubular extension member (22) thereof and having an external diameter substantially equal thereto, a downhole tool sub-assembly (20) and a protective arrangement comprising an annular seal means (30) characterised in that said annular seal means (30) has an inner surface (40) dimensioned to fit around said tube member (18) and an outer surface (46) dimensioned to fit within at least art upper end of said sleeve member (24), said inner surface (40) being provided with an inner fluid seal means (42,44) for forming a sliding fluid seal to the exterior (19) of said tube member (18), said outer surface (46) being provided with an outer fluid seal means (48,50) for forming a sliding fluid seal to the interior of said sleeve member (24) and the downhole tool sub-assembly (20) being located within an annular Volume (C) between the seal member (26) and said annular seal means (30), the Volume (C) being constant nothwithstanding movement of the tube member (18) relative to the sleeve member (24).
A downhole tool assembly comprising a sleeve member (24), a tube member (18) partially located within said sleeve member (24), a running tool sub-assembly (20) below the tube member (18) and a tubular extension member (22) depending from the running tool sub-assembly (20), characterized in that the external diameter (19) of the tube member (18) is equal to the external diameter of the tubular extension member (22).
A downhole tool assembly comprising a sub-assembly (20) being located within an annular volume (C) externally bounded by a bore (25) of a sleeve member and internally bounded by an exterior surface (19) of a tube member (18) in conjunction with an exterior surface of a tubular extension (22) and the sub-assembly (20) linking them, and further bounded at a lower end by an annular seal (26) and at an upper end by a junk bonnet (30), characterized in that longitudinal movement of the tube member (18) together with the tool sub-assembly (20) and the tubular extension member (22) with respect to the sleeve member (24) and the seal (26) causes no change in the volume (C).
Dependencies are inferred from the claim text.