What is the name for the point above which there is no tendency to buckle in a drill string?

What is the name for the point above which there is no tendency to buckle in a drill string?

• A. Critical Point
• B. Neutral Point
• C. Buckling Point
• D. Torsion Point

Answer: (B)

Buckling under axial load is a common concern for a drill string, and the load it carries isn’t the same from top to bottom. Friction and contact with the wellbore walls cause part of the weight to be supported by the formation, so the compressive force along the string decreases with depth. There is a depth where the axial force in the string above that point becomes zero, and beyond this point the segment above does not experience net compression that could cause buckling. That depth is called the neutral point, and it marks the boundary above which there is no tendency to buckle. So, the name for the point above which buckling tendency disappears is the neutral point.

Buckling under axial load is a common concern for a drill string, and the load it carries isn’t the same from top to bottom. Friction and contact with the wellbore walls cause part of the weight to be supported by the formation, so the compressive force along the string decreases with depth. There is a depth where the axial force in the string above that point becomes zero, and beyond this point the segment above does not experience net compression that could cause buckling. That depth is called the neutral point, and it marks the boundary above which there is no tendency to buckle. So, the name for the point above which buckling tendency disappears is the neutral point.