Boring or penetrating the earth – With means movable relative to tool or shaft to control...
Patent
1997-01-31
1999-06-15
Dang, Hoang C.
Boring or penetrating the earth
With means movable relative to tool or shaft to control...
166222, 1663324, 175324, 175424, E21B 2110
Patent
active
059112859
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to downhole tools for use in the drilling of oil wells in the like, for diverting a portion of the flow of drilling fluid (mud) through a drill string out of apertures formed in the tools, which form part of the drill string, for the purpose of assisting in the clearance of cuttings from the annulus around the drill string. The invention is applicable particularly, but not exclusively, to high angle or horizontal long-reach wells.
In the drilling of oil wells or the like, cuttings from the drilling operation are flushed back to the surface of the bore by drilling fluid which circulates down through the interior of the drill string and returns to the surface through the annulus around the drill string. In high angle or horizontal wells, difficulties are often experienced in effecting adequate flushing of such cuttings.
In order to alleviate such problems, it is known to deploy a circulating sub in the drill string. A circulating sub is simply a cylindrical sub having an aperture formed in its side through which drilling fluid is diverted out to the annulus around the drill string for flushing cuttings. The sub is plugged at its lower end in order to divert the fluid, so that drilling operations have to be interrupted while the circulating sub is deployed. Circulating subs of this type also have a limited life owing to erosion by the abrasive fluid.
A further problem associated with long reach wells is that the formation through which the bore is formed is liable to collapse around the drill string, trapping the drilling assembly.
It is a first object of the present invention to provide fluid diverter tools which allow drilling fluid to be diverted for enhanced flushing of cuttings and other debris without interrupting drilling operations.
It is a second object of the invention to provide fluid diverter tools having enhanced resistance to erosion.
It is a further object of the invention to provide diverter tools further adapted to allow back-reaming of a collapsed formation to free a trapped drill string.
In accordance with the invention there is provided a downhole fluid diverter tool comprising: a generally cylindrical body having an axial through-bore and adapted for connection within a drill string, said body having at least one aperture formed in a side wall thereof; at least one generally cylindrical insert having an axial through bore and having at least one aperture formed in a side wall thereof; means for locating said insert within said cylindrical body such that said apertures of the body and the insert are aligned with one another; and means whereby a proportion of a flow of drilling fluid passing through the cylindrical body, in use, may be diverted through said apertures.
Preferably, said body has a plurality of apertures and said at least one insert provides a corresponding number of apertures aligned therewith. Most preferably, an insert having a single aperture is provided for each aperture formed in the body, said apertures formed in the body being spaced along its length and said inserts being stacked in the interior thereof. More preferably still, the apertures in the body are disposed in a helical path along its length.
Preferably also, said at least one insert is formed from erosion resistant material; most preferably said material is tungsten carbide.
Preferably also, the tool further includes a nozzle assembly located in each of said apertures in said body. Most preferably, said nozzles are located in the apertures of said body and engage said inserts, thereby also providing said locating means.
In a variation of the invention, said generally cylindrical body is further provided with a plurality of stabilising blades on its exterior surface and said apertures extend through said blades.
Preferably, said blades are provided at their uppermost ends with cutting elements whereby rotation of the tool may provide a back-reaming action. In this case, the uppermost aperture preferably extends through one of said blades at an angle to the side wall of the cylindr
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Craig Mark William
Stewart Arthur Deacey
LandOfFree
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