Drillstring Basics

Drillstring Basics


Upon completion of this section you will be able to:

• Explain how drill pipe grades define the yield strength and tensile
strength of steel.
• Explain how drill pipe is classified.
• Calculate total yield strength for a specific grade/class of drill pipe.
• Explain the effects of buoyancy on the drillstring.
• Calculate the buoyed weight (or hookload) in a vertical hole.
• Explain the causes of varying hookload during the drilling process.
• Explain overpull and calculate the maximum permitted pull.
• Calculate required BHA air weight for applications where drill pipe is
to be run in compression.
• Calculate critical buckling force and explain the factors involved
when running drill pipe in compression.
• Explain causes and effects of sinusoidal and helical buckling.
• Explain neutral point and calculate the approximate location of the
neutral point in a rotary drillstring.
• Explain the relationship between cyclic bending stress and drill pipe
fatigue.
• Describe some of the factors affecting axial drag and torque, and the
effect of drag on weight on bit.