| Downhole apparatus for mobilising drill cuttings -> Monitor Keywords |
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  Downhole apparatus for mobilising drill cuttingsRelated Patent Categories: Boring Or Penetrating The Earth, Bit Or Bit ElementThe Patent Description & Claims data below is from USPTO Patent Application 20070215388. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention relates to apparatus for mobilising drill cuttings in an oil or gas well. [0002] The art of drilling wellbores for recovery of oil and gas is well known. One particular problem faced by this art is the removal of cuttings from the well as they are generated by the action of the drill bit cutting into the formation. The cuttings need to be removed from the bit and conveyed back to surface as efficiently as possible, as their persistence in the wellbore hampers drilling activity, and tends to reduce the productivity of the well. [0003] Cuttings are washed back to surface by drilling mud or fluid pumped down the string, out through the bit, and back up the annulus surrounding the string. This solution is generally satisfactory, but in long and deviated wells we have found that cuttings still tend to clump and impede the drilling activity, or the production of the well. [0004] According to the present invention there is provided apparatus for mobilising drill cuttings in a well, the apparatus comprising at least one vane, and two or more blades defining at least one fluid conduit between adjacent blades, the blades and vane being rotatable relative to one another. [0005] Typically the blades are configured to create a pressure difference in fluid flowing through the conduit, but this is not essential, and a fluid drop, if required, can be induced by other means apart from the blades. [0006] The apparatus typically comprises a sleeve or collar, which is typically tubular and is adapted to fit over a string in the well. The string can be a tubing string, drill string, or casing string etc. Typically the vanes are provided on the sleeve. [0007] Typically the blades are mounted on a bushing that is rotatably mounted on the sleeve. [0008] However, in certain simple embodiments, it is sufficient to provide the vanes direct on the tubing string (or on a sleeve attached to the string) and to provide the blades on an adjacent part of the string, or on a separate sleeve attached thereto, so that the blade-bearing bushing is not directly attached to the vane-bearing sleeve. The blades or the bushing can optionally be incorporated into a sub in the string, or on a collar that is separately attached to the string. [0009] Typically the sleeve is adapted for attachment to a drill string, and the fixing means typically comprises a clamp means such as an annular clamp to fix the sleeve over the outer surface of the drill pipe. However, the sleeve may equally attach to casing or any other oilfield tubular goods. [0010] The vanes can be carried direct on the sleeve, or in some embodiments can be provided on a separate bushing rotationally (or otherwise) affixed to the sleeve. The vanes typically rotate with the drill string in normal rotary drilling operations as they are typically rotationally fixed to the drill string. The rotation of the vanes agitates the fluid surrounding the apparatus, and creates thrust tending to drive the fluid past the sleeve. The blades of the bushing typically create a pressure drop in the fluid as it flows past the apparatus, driven by the rotation of the vane(s). [0011] Typically the bushing is free to rotate relative to the sleeve, which is affixed to the drill string. Thus, upon rotation of the drill string (or casing) during normal rotary drilling, the bushing typically remains stationary relative to the wellbore, while the drill string rotates. [0012] Typically the blades on the bushing project radially outward to a greater extent than the vanes of the sleeve, so that the radially outermost surface of the blades contacts the inner surface of the bore within which the string is located, and this centralises the sleeve within the bore. In preferred embodiments, the vanes are radially lower than the blades, and can freely rotate within the bore, as the higher blades provide a stand off against the inner surface of the bore. The bore can be the unlined wellbore, or can be the bore of casing, liner or other tubing in which the apparatus is located. [0013] The blades can be set parallel to the axis, or can be offset with respect to it, so that they extend helically around the bushing. In some embodiments the blades are offset at an angle of 3-10.degree. e.g. 5.degree. from top left to bottom right with respect to the axis of the bushing. This orientation is useful in drillstrings that are conventionally rotated to the right, as the fluid path up the annulus tends to flow in a spiral from bottom right to top left at around 5.degree. off the axis. Therefore, the offset blades do not substantially impede the fluid flow rate. Clearly adjustments can be made to the offset angle to suit the fluid flow direction in other wells. [0014] The blades typically have an asymmetric profile, and in preferred embodiments the blades are shaped in the form of foils, so that the fluid conduits defined between adjacent blades on the bushing change in profile. Typically the fluid conduits are relatively narrow at a lower end (nearest the drill bit) and grow relatively wider toward the upper end (furthest away from the bit). The increase in dimension from the bottom of the channel to the top causes a pressure drop in the fluid flowing through the channel. [0015] The blades can have profiled cross sections (i.e. end-on view) in the form of an hour glass, with a wide root radially innermost adjacent the bushing, a wide top at the radially outermost part of the blade that bears against the borehole wall, and a narrower cutaway portion between the two to facilitate fluid flow between the blades. This cutaway creates more space for the fluid to pass between the blades, and helps to avoid impedance of the fluid flow. [0016] Typically the bushing can be formed from a rigid material, such as hard rubber or metal. The sleeve is typically formed from metal such as steel, alloy, aluminium, etc. [0017] The sleeve can have an annular body to fit around a tubular or string of tubulars. The annular body can have the vanes integrally formed with it, for example by moulding the sleeve and vanes as a single piece. In alternative (and preferred) embodiments, the sleeve can have vane-receiving recesses therein to receive and retain modular vanes, which can be slotted in the recesses, and retained therein. This has the advantage that several different sizes of vanes can be used with a single sleeve. [0018] Likewise, the blades on the bushing can be modular and can be received within blade recesses in the same manner. [0019] The vanes can be curved or straight, and can lie parallel to the axis, but in typical embodiments they cross the axis of the sleeve so as to scoop the fluid from the annulus. The lower end of the vane is typically circumferentially spaced around the sleeve from the upper end, typically in the direction of rotation of the string, so where the string rotates to the right (as is conventional in most wells) the vanes are offset across the axis from top right to bottom left, the opposite configuration from the offset blades described above. [0020] In some embodiments the vanes are configured in a sinusoidal "lazy-s" shape and this helps to agitate the fluid surrounding the apparatus during rotation. In other embodiments, they are disposed straight across the axis. [0021] The vanes can have concave surfaces to assist in the scooping action, and typically the concave surfaces can be provided in one side of the vane only, typically on the side of the vane facing the direction of rotation. The concave surface can be regular and unchanging along the side of the vane, but in some embodiments the side vane is shaped to have more of a curve on its upper end than on its lower end, so that as the fluid moves up the side of the vane, the increasing curve of the concave surface keeps the fluid close to the sleeve, where most turbulence will be generated, thereby keeping the cuttings in suspension for longer. [0022] The or each vane can be provided with a notch cut away from a radially outermost portion of the vane. Several notches may be provided on each vane. The notches can serve to introduce additional turbulence or induce a vortex as the vane is rotated to agitate drill cuttings and entrain them into the flow of fluid up the annulus. [0023] The invention also provides a drill cuttings agitation assembly, comprising a tubular, a vane, and at least two blades defining at least one fluid conduit between adjacent blades, wherein the vane and the blades are rotatable relative to one another. [0024] The invention also provides a method of agitating drill fluid in an oil or gas well, the method comprising passing the drill fluid past a vane rotatable relative to at least two blades. Continue reading... Full patent description for Downhole apparatus for mobilising drill cuttings Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Downhole apparatus for mobilising drill cuttings patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Downhole apparatus for mobilising drill cuttings or other areas of interest. ### Previous Patent Application: Solids strainer system for a hydraulic choke Next Patent Application: Matrix drill bits with back raked cutting elements Industry Class: Boring or penetrating the earth ### FreshPatents.com Support Thank you for viewing the Downhole apparatus for mobilising drill cuttings patent info. 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