Connection Assembly For Drill Collars or Heavy Drill Pipes

Abstract

The invention relates to a connection assembly ( 100 ) for drill collars or heavy drill pipes comprising: a male connection element which comprises, in its longitudinal direction, an at least partially threaded conical surface portion which tapers from the first portion towards its free end; a female connection element which comprises an at least partially threaded conical inner surface and a cylindrical inner surface ( 220 ), said two connection elements being complementary so that one can be assembled in the other by screwing, characterized in that the male connection element additionally comprises, between its free end and said conical surface portion, another surface portion whose conicity is less than that of said surface portion and which is dimensioned with respect to said cylindrical inner surface ( 220 ) such that there is a clearance by virtue of which these two surfaces bear one against the other when the assembly is subjected to a bending stress.

1 . Connection assembly ( 100 ) for drill collars or heavyweight drill pipes, comprising:
 a male connecting element ( 300 ) having a substantially circular section about a longitudinal axis and that includes within its longitudinal direction, respectively:
 a substantially cylindrical first portion ( 302 ) forming a shoulder ( 301 ) at one of its ends, 
 an at least partly threaded second conical surface portion ( 310 ) tapering from the first portion toward the free end of the element, 
   a substantially cylindrical female connecting element ( 200 ), complementary to said male connecting element, including:
 a radial portion ( 201 ) forming a bearing face for said shoulder ( 301 ) of the first element and, longitudinally, coaxially and respectively, from that portion, 
 an at least partially threaded conical interior surface complementary to the at least partially threaded conical surface of the male element, 
 a cylindrical interior surface, 
   
     said two connecting elements being intended to be assembled one into the other by a screwing action entailing several turns of the threads, characterized in that the male connecting element further includes, between said second portion and its free end, a third surface portion of lower taper than the second portion of the conical surface and sized relative to said cylindrical interior surface so that there exists a gap whereby these two surfaces come respectively into bearing contact if the assembly is stressed in bending. 
   
   
       2 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the male element ( 300 ) includes a groove ( 340 ) disposed between said second portion ( 310 ) and said third portion ( 330 ), so that, when said two elements are assembled together, and when said shoulder ( 301 ) is abutted against the radial bearing face, the geometrical limit between said conical interior surface and said cylindrical interior surface is in the space formed by said groove. 
   
   
       3 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the third surface portion ( 330 ) of the male element forming a bearing surface is substantially cylindrical. 
   
   
       4 . Connection assembly ( 100 ) according to  claim 3 , characterized in that said portion ( 330 ) is partially conical at its free end. 
   
   
       5 . Connection assembly ( 100 ) according to  claim 4 , characterized in that said taper is less than that of the at least partly threaded second conical portion ( 310 ). 
   
   
       6 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the third portion ( 330 ) has a longitudinal dimension at most equal to ⅔ of the longitudinal dimension of the second portion ( 310 ). 
   
   
       7 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the third portion ( 330 ) has a longitudinal dimension from 10% to 50% of its diameter. 
   
   
       8 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the groove ( 340 ) has a radius of curvature from ½ to 3 inches, i.e. from approximately 12 millimeters to 76 millimeters. 
   
   
       9 . Connection assembly ( 100 ) according to  claim 1 , characterized in that the two elements ( 200 ,  300 ) are axially bored and open-ended. 
   
   
       10 . Male connecting element ( 300 ) for heavyweight drill pipes or drill collars intended to cooperate with a female element ( 200 ) and having a substantially circular shape about a longitudinal axis, including in its longitudinal direction, respectively:
 a substantially cylindrical first portion ( 302 ) forming a shoulder ( 301 ) at one of its ends,   an at least partly threaded second conical surface portion ( 310 ) tapering from the first portion toward the free end of the element,   characterized in that the male connecting element further includes, between said second portion and its free end, a third surface portion ( 330 ) of smaller taper than the second conical surface portion.