RADIO-FREQUENCY-IDENTIFICATION CHIPS FOR DRILLSTRING ELEMENTS

摘要

Drillstring elements are subjected to several kinds of cyclic stress. These cyclic stresses, often above the endurance threshold, cause the accumulation of fatigue and eventual failure of the element during a drilling operation. Regular inspections look for wall wear, tool-joint-diameter reduction, oval-ization, crookedness, thread damage, and microcracks along the length of the drill-string elements. If too many defects are found in an element, it might be degraded or discarded as junk. Fatigue is a mechanical phenomenon that causes a body to fail in a sudden mode when subjected for long periods to alternating or fluctuating stresses. Current inspection technology cannot measure quantitatively the amount of accumulated fatigue in a steel drillstring element. However, numerical methods exist that can approximate the accumulated fatigue in a drillstring element if the history of mechanical conditions is known from the time of fabrication.