Paper: Drill String Fatigue in Short Radius Horizontal Applications

Damaged pipe, especially in horizontal applications, is costly. The large number of planned horizontal drilling projects
coupled with the expense of pipe replacement and fishing operations made it imperative that Mobil E&P gain a better understanding of drillpipe life. Previous internal studies of failure flurries have shown that excessive doglegs, high H2S environments, and improper specifications or makeup on tubing connections can accelerate fatigue leading to failure. The effect of high bending stresses on drill pipe connections is also a concern. Inspections, typically used to determine pipe condition, prove only obvious defects and not fatigue. The goal is to evaluate DPLIFE2's ability to predict failures by comparing the program result with actual failures. Another objective is to evaluate the overall consumed life of the tubing and determine a "best practice" for replacing pipe before failures occur.