Drilled pile

Abstract

A method of installing a pile 10 in a subsea substrate is provided, which method comprises the steps of providing a pile 10 with a drill bit 14 at one end, and rotating both the pile 10 and the drill bit 14 relative to a substrate to form a bore. Also provided is a subsea pile 10 in the form of an elongate member 12 with a drill bit 14 fixed at one end thereof. In certain embodiments, the elongate member 12 may be tubular, allowing fluids to be supplied to the drilling face via the pile. Such fluids may be drilling mud, sea water, or a settable material for fixing the pile in the bore. In preferred embodiments of the invention an upper portion of the pile may be adapted to be laterally flexible.

What is claimed is:  
     
         1 . A method of installing a pile in a subsea substrate, the method comprising the steps of: 
 providing a pile with a drill bit at an end thereof; and    rotating and advancing the pile and the drill bit relative to a substrate to form a bore.    
     
     
         2 . The method of  claim 1 , wherein the drill bit is not recovered.  
     
     
         3 . The method of  claim 1 , wherein the pile is an elongate tubular member and drilling fluid is supplied to the drill bit via the pile.  
     
     
         4 . The method of  claim 1 , further comprising the step of securing the pile in the bore.  
     
     
         5 . The method of  claim 4 , wherein the pile is secured in the bore by passing a settable material into the bore, between the pile member and the bore wall, and allowing the material to set in the bore.  
     
     
         6 . The method of  claim 5 , wherein the settable material is delivered to the bore via an internal bore in the pile.  
     
     
         7 . The method of  claim 1 , wherein the pile is at least partially formed from standard oilfield tubulars.  
     
     
         8 . The method of  claim 1 , wherein the pile and drill bit are rotated by a driven elongate member connected thereto.  
     
     
         9 . The method of  claim 8 , wherein the connection between the elongate member and the pile is broken from surface once the pile is installed to the correct depth, such that the elongate member may be retrieved.  
     
     
         10 . The method of  claim 9 , wherein the connection is positioned at a level relative to the substrate surface such that the pile does not have to be recovered once the pile is no longer in use.  
     
     
         11 . The method of  claim 8 , wherein the elongate member extends to and is rotationally driven from surface.  
     
     
         12 . The method of  claim 8 , wherein the elongate member is rotationally driven by a motor positioned below the surface of the water.  
     
     
         13 . A subsea pile comprising an elongate member with a drill bit fixed at one end thereof.  
     
     
         14 . The pile of  claim 13 , wherein the pile is an elongate tubular member.  
     
     
         15 . The pile of  claim 13 , wherein at least an upper portion of the pile is adapted to flex one or both of elastically and plastically in response to lateral loading.  
     
     
         16 . The pile of  claim 13 , wherein the pile comprises standard oilfield tubulars.  
     
     
         17 . The pile of  claim 15 , wherein the resistance of the pile to lateral forces varies along its length, such that the bending characteristics and bending radii of the pile may be controlled.  
     
     
         18 . The pile of  claim 17 , wherein a lower portion of the pile is relatively rigid.  
     
     
         19 . The pile of  claim 13 , wherein a lower portion of the pile is adapted to be grouted or cemented in the bore.  
     
     
         20 . The pile of  claim 13 , wherein a lower portion of the pile comprises relatively high rigidity members, including one or more of heavy section drill pipe, drill collars and bore casing.  
     
     
         21 . The pile of  claim 13 , wherein an upper portion of the pile is adapted to bend when subjected to lateral forces and translate the lateral forces to axial forces which are substantially withstood by the lower portion of the pile.  
     
     
         22 . The pile of  claim 13 , wherein the pile is provided with a mooring line connection.  
     
     
         23 . The pile of  claim 22 , wherein the mooring line connection includes a flexible member.  
     
     
         24 . The pile of  claim 23 , wherein a portion of the connection is buoyant, to facilitate location of the connection following installation of the pile.  
     
     
         25 . The pile of  claim 13 , in combination with an elongate member for extending to surface, and a connection between the elongate member and the pile which is adapted to be broken from surface once the pile is installed to the correct depth, such that the elongate member may be retrieved.  
     
     
         26 . The combination of  claim 25 , wherein the connection is a low torque back-off disconnection system.  
     
     
         27 . The combination of  claim 25 , wherein the elongate member is adapted to be rotationally driven from surface.  
     
     
         28 . The combination of  claim 25 , further including a motor for location below the sea surface.  
     
     
         29 . A pile comprising an elongate member with a drill bit at one end thereof, wherein the pile has at least an upper portion adapted to flex in response to application of lateral loading thereto.