Drill pipe for rotary drilling

Abstract

A drill string element for rotary drilling includes a threaded connection at a forward and/or a rearward end of the drill string element; a central flushing channel extending longitudinally through the drill string element; and a first flat and a second flat positioned along an outer surface of the drill string element closest to the threaded connection. Each flat includes at least two flattened sections on diametrically opposite sides of the drill string element, wherein the first flat and the second flat have different diameters to accommodate gripping tongs of different diameters.

What is claimed is: 
     
         1 . A drill string element for rotary drilling, comprising:
 a threaded connection at a forward and/or a rearward end of the drill string element;   a central flushing channel extending longitudinally through the drill string element; and   a first flat and a second flat positioned along an outer surface of the drill string element closest to the threaded connection, each flat including at least two flattened sections on diametrically opposite sides of the drill string element, wherein the first flat and the second flat have different diameters to accommodate gripping tongs of different diameters.   
     
     
         2 . The drill string element of  claim 1 , wherein the first flat and the second flat are circumferentially rotated relative to each other. 
     
     
         3 . The drill string element of  claim 2 , wherein the first flat and the second flat are rotated approximately 90 degrees relative to each other. 
     
     
         4 . The drill string element of  claim 1 , wherein the at least two flattened sections are positioned in diagonally opposite quadrants of a cross-section of the drill string element. 
     
     
         5 . The drill string element of  claim 1 , wherein an axial distance between the first flat and the second flat is at least 15 centimeters. 
     
     
         6 . The drill string element of  claim 1 , wherein the drill string element is a drill pipe. 
     
     
         7 . The drill string element according to  claim 6 , further comprising a third flat and a fourth flat positioned near an opposite end in relation to the first flat and the second flat of the drill string element, each of the third and fourth flats having diameters corresponding to those of the first and second flats respectively. 
     
     
         8 . The drill string element of  claim 6 , wherein the drill string element has a total length between 6 and 11 m. 
     
     
         9 . The drill string element of  claim 6 , wherein the drill string element has an outer diameter of between 20 and 24 cm. 
     
     
         10 . The drill string element of  claim 1 , wherein the drill string element is a starter sub, an extension sub or a shock sub. 
     
     
         11 . The drill string element of  claim 10 , wherein the drill string element has a total length between 2.5 and 3 m. 
     
     
         12 . The drill string element of  claim 1 , wherein the drill string element is a claw bit, a pick bit, a fixed cutter bit or a tricone. 
     
     
         13 . The drill string element of  claim 1 , wherein an axial extension of each flat is between 10 and 20 cm.