Boring or penetrating the earth – With tool shaft detail – Shaft carried guide or protector
Reexamination Certificate
1998-02-12
2001-04-03
Neuder, William (Department: 3672)
Boring or penetrating the earth
With tool shaft detail
Shaft carried guide or protector
C175S228000, C175S325500
Reexamination Certificate
active
06209667
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fitting for reducing friction between a drill string and the wall of a well. More particularly, but not exclusively, in a first aspect the present invention relates to a fitting having a plurality of longitudinal recesses enabling lubrication between the fitting and a drill string using drilling fluid. According to a second aspect there is provided a fitting having rotatable rollers to reduce both axial and rotational friction. According to a third aspect there is provided a fitting having an outer section rotatable relative to an inner section secured about a drill string.
BACKGROUND OF THE INVENTION
The depth to which and angle at which a well can be drilled are often limited by the degree of friction experienced by the drill string. The life of a drill string may also be reduced due to friction. With increasing environmental concerns it is also becoming less acceptable to reduce friction by injecting chemicals down a well. Using wellstream fluids as a lubricant results in drill string wear due to particulate matter carried in the fluids. Further, currently available similar fittings cannot be rebuilt or reconditioned.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a fitting which reduces the friction on a drill string or at least to provide the public with a useful choice.
According to a first aspect of the invention there is provided a fitting for reducing friction between a fitting and a section of a drill string or further fitting on a drill string, said fitting comprising a body having a tubular bore provided with a plurality of longitudinally extending recesses spaced circumferentially about the bore, dimensioned to lubricate the interface between the fitting and the drill string or further fitting with fluid in a drilling well, wherein rollers are provided about the periphery of the body to reduce friction in the axial direction.
Preferably the bore of the fitting has a polygonal cross-section. In another embodiment the fittings may have a substantially circular cross-section and the sleeve may have a polygonal cross-section. The fitting may preferably be formed as a two part casing which can be secured to an assembled drill string.
According to a further aspect of the invention there is provided a fitting for engagement to a drill string or further fitting having a body with a bore therethrough provided with a plurality of roller means on the exterior of the body, each said roller means having one or more roller provided thereon and being rotatable relative to the body about an axis transverse to the axis of the bore, the arrangement being such that the roller means can rotate relative to said body to facilitate reduction of rotational and axial friction.
Preferably, the rollers have a substantially tapered cylindrical form and rotate about an axis transverse to the axis of rotation of the roller means. The body may be of two part construction and the rollers are preferably formed of a nylon or ceramic material.
According to a further aspect of the invention there is provided a fitting for engagement with a drill string or further fitting comprising an inner section for securement to a drill string or further fitting, an outer section for securement about said inner section, a bearing located between the inner section and outer section, seals provided at either end of the fitting between the inner section and outer section and pressure compensating means for maintaining the pressure within the bearing substantially the same as the external pressure.
Preferably a plurality of fins project radially from the outer section which are profiled to reduce drag in the axial direction.
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Fernandes Denis Robert
Murray Geoffrey Neil
Fulbright & Jaworski L.L.P.
Neuder William
Weatherford / Lamb, Inc.
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