Abstract: A member M provides a preferred combination of reduced weight with increased resistance to buckling under compressive loading and includes a tubular member 10 with tool joints TJ at each end for connection to form a drill stem. The tubular member 10 further includes a first portion or pipe section 15 adjacent either one of the tool TJ and may include a second portion or pipe section 15' adjacent the other tool joint TJ which are of smaller or reduced diameter than the adjacent tool joint. An enlarged portion 20 extends longitudinally of the tubular member from adjacent the first portion to adjacent the second portion where there is a second portion adjacent the other tool joint. If there is only one first portion adjacent one tool joint, the enlarged diameter extends from adjacent such first portion to the tool joint at the other end of the tubular member. The enlarged portion 20 has a larger inner and outer diameter than the adjacent first portion.

Abstract: A drill collar is formed by inner and outer tube means having an annular space extending longitudinally therebetween. Rigid filler material in the annular space forms, with the inner and outer tube means, a unitary elongated tubular structure. The rigid filler material precludes movement of the inner and outer tube means relative to each other. A longitudinal bore extends through the tubular structure.