Patent Publication Number: US-9404317-B2

Title: Modified tubular

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 14/374,442 filed 24 Jul. 2014, which is a U.S. National Stage application of PCT/EP2013/057416 filed 9 Apr. 2013, which claims priority to Great Britain patent application 1215868.9 filed 5 Sep. 2012, the entire disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Oil and gas reservoirs may be exploited by tapping the resources therein via wellbores. Drilling of wellbores may require drilling a considerable distance into the earth. Many oil &amp; gas bearing formations are at sub-sea locations. The direction of drilling may vary from a vertical position to a horizontal position. The wellbore created by drilling may be stabilised by use of casing or lining or by other measures. Tubular bodies (hereinafter “tubulars”) may be positioned in the wellbore. The tubular bodies may be cemented into position. The positioning of tubulars in the wellbore may be complicated by variations in wellbore direction. Tubulars may have mechanical components mounted thereon for the purposes of improving alignment and stable positioning of the tubulars in the wellbore. Correct positioning of the tubulars permits cementing to a satisfactory standard. 
     SUMMARY 
     A positioning member may be formed and applied to a tubular. The forming process may comprise prefabrication of an outer part followed by application and bonding of the outer part to the tubular. The formed positioning member provides a protrusion upon the surface of the tubular. 
     The positioning member may comprise a shell configured to a desired external shape. The external shape of the shell may be configured to form straight, curved, helical or spiral shaped positioning members. The shell may have an external contact or bearing surface, which may be generally planar or outwardly curved (convex), with bevelled side surfaces. The shell may have peripheral edges including portions adapted to allow passage of a flowable material. The peripheral edge portions may be indented, recessed, notched, serrated, apertured, crenulated, slotted or otherwise include a discontinuity which may form a flow port when the peripheral edge is presented against a parallel surface. The depth of the shell is selected to provide a clearance or spaced position from a surface such as the wall of a borehole. 
     The interior surface of the shell may be configured to provide a plurality of projections, curved ridges, a fish scale pattern or any other relief pattern. 
     The shell may be structurally reinforced by provision of one or more strengthening members. The strengthening member may be a strut, brace, a rib or an equivalent thereof. Such structural reinforcement may extend between two opposite sides of the shell. 
     The shell may be formed from a composite material. The composite material may be a fibre-reinforced resin material (FRP/GRP/GFK type material). The resin material is a hardenable resin optionally including curing agents and curing modifiers. The resin may be self-curing, or provided in two components which harden when brought together. The two component system may be a matrix-forming (pre-polymer) component and a hardener. Suitable resins include epoxy resins, polyurethanes and polyurea resins including blends or hybrids thereof, and other curable resin components including polyester or polyol or polyamine components. The curing of the resin may be controlled by use of amine curing agents such as polyetheramines. Other additives may be present. 
     The fibre-reinforced resin material may be surface treated before moulding of the shell. The fibre-reinforced resin material may have a ceramic particulate applied. The fibre-reinforced material may have a friction-modifying material applied. A combination of such surface treatments may be used. The surface treatment may be a surface modifying finish to an external surface of the moulded shell. 
     Additional particulate materials may be present within the bulk of the fibre-reinforced resin material. The particulates may be in bead form. 
     The shell may have at least one inlet for passage of flowable materials, such as bonding agents. The shell may be bonded to an external surface of a tubular. Bonding agents may be introduced into a void between the tubular and the shell by injection through the at least one inlet. 
     The shell may be temporarily located upon a tubular, prior to introducing bonding agents into the shell, using temporary fastenings so as to enclose a void between the tubular and the shell. The temporary fastenings may be a contact adhesive or releasable fasteners which may include ties, wires, straps, an adhesive tape and various combinations thereof. 
     Embodiments incorporate the disclosed summary features individually or in a variety of combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view from below and to one side of a fibre reinforced composite shell body; 
         FIG. 2  is a perspective view form above and to one side of a fibre reinforced composite shell body; 
         FIG. 3  is a perspective view from one end of a fibre reinforced composite shell body; and 
         FIG. 4  is a side view of a tubular modified by application of fibre reinforced composite shell bodies. 
     
    
    
     DETAILED DESCRIPTION 
     Manufacture of Shell 
     In an embodiment, a permanent mould or form is designed and constructed according to shape requirements for the shell form to be manufactured, that is, the geometry required for the intended positioning member. The shape requirements are derived from known dimensions of a tubular and its intended use in a wellbore. A choice can be made amongst protrusions of straight, curved or spiral or helical configurations. A number of differing moulds may be produced to enable a variety of positioning members to be manufactured at will. 
     The mould is used to form materials into a prefabricated shell which is suitable to form part of a positioning member which is to be provide on a tubular. 
     In an embodiment, a fibre mat is infused with a resin matrix. This is achievable by passing the fibre mat through a bath containing the resin matrix. Infusion may also be achievable in other ways, such as applying the resin matrix liberally to the fibre mat by pouring or spraying or by a pressure treatment to soak, or impregnate the fibre mat with the resin matrix. 
     Ceramic particulates, for example hard wearing materials such as a combination of zirconium dioxide and silicon nitride, optionally in bead form, may be applied to the resin matrix infused fibre mat. 
     A friction modifying material such as fluorocarbon particulates providing a low friction coefficient also may be applied to the resin matrix infused mat. 
     The resin matrix infused fibre mat may be introduced to the mould such that surfaces treated with the aforesaid particulates are adjacent to the mould surfaces. Multiple additional layers of the resin matrix infused fibre mat, which may or may not each have been treated with particulates, may be laid up into the mould on to the first resin matrix infused fibre mat lining the mould until a predetermined thickness is attained. 
     Then the mould may be closed. 
     A resin filler matrix may be introduced into the mould using a low pressure resin transfer moulding process. In an example of such a process, a mixed resin and catalyst or resin curing agent are introduced, for example by injection, into a closed mould containing a resin matrix infused fibre and particulates lay up. In this way a composite shell may be formed. 
     The mould may be heated in order to achieve first cure. 
     After sufficient curing of the resin to permit handling of the shell, the mould can be opened and the formed shell removed. 
     If necessary a post cure of the formed shell may be carried out. Post cure may be a heat treatment, for example conducted in an oven. 
     Technical Features of the Shell 
     Referring to  FIG. 2 , an embodiment of the shell  1  has an outer contact or bearing surface  2  which is generally planar with peripheral sloping or bevelled sides  3 ,  4  and ends  6 ,  8 . Other embodiments may have a convex curved bearing surface or faceted contour surface. The outer bearing surface  2  is provided with injection inlet ports  5 . 
     Referring to  FIG. 1 , the shell has peripheral edges  13 ,  14  adapted to allow passage of a flowable material. Provision of recesses  23 ,  24  in portions of the peripheral edges  13 ,  14  provides a series of apertures when the peripheral edges  13 ,  14  are in contact with a parallel surface. 
     Referring to  FIG. 1 , an inner surface  12  of the shell  1  is configured to provide a plurality of curved ridges  15 , or fish scale pattern, to provide a keying surface to improve adhesion or bonding with a bonding material. 
     Optionally, the shell is formed to include structural reinforcements such as one or more integral strengthening struts, braces or ribs  16  extending from one side  3  to an opposite side  4 . One such transverse strut  16  is shown in  FIG. 1 . 
     Modification of a Tubular 
     In use of the shell  1  to form a positioning member  11 , a selected outer surface area of a tubular  10  is prepared in order to provide a clean, dry substrate with an appropriate surface profile for receiving the shell. 
     A prefabricated shell  1  of appropriate dimensions is presented to the prepared area, so that edges  13  and  14  are contiguous with the surface of the tubular. The shell  1  is held in position temporarily by use of releasable fastenings such as removable straps, or adhesive tape. A cavity is thereby defined between interior surfaces of the shell  1  and the prepared area of the tubular. 
     A bonding material is injected into the shell cavity through one or more inlet ports  5  in the surface of the shell  1  until it flows through the apertures defined between the recesses  23 ,  24  and the surface of the tubular. 
     When a period sufficient for curing of the bonding material has elapsed, the straps and/or adhesive tape may be removed. 
     By this method the prefabricated shell becomes an integral part of the positioning member bonded to the tubular. 
     The tubular is thereby modified to have a surface mounted positioning member which facilitates appropriate positioning of the tubular in a borehole. 
     Additional positioning members may be formed on the tubular by repetition of the above described methods and procedures. 
     Variations, modifications of the disclosed embodiments contemplated by the person skilled in the field are within the scope of the disclosure, and with regard to scope, attention is directed to the following claims which form part of the present disclosure and extend to all equivalents of the disclosed subject matter.