Statistical modeling of drill pipes operational life-time under a regular loading
A formula for estimating the operational life-time of drill pipes is derived from the equation of the fatigue curve, in which the stress amplitudes, endurance limit, basic number of cycles and rotation speed are specified by the normal law. It is established that drill pipes operational life-time obeys the lognormal distribution. As a result, their reliability indicators are found. The implementation of the algorithm led to a reduction of accidents and complications of a drill string while drilling wells with heavy oil up to 4200 meters depth.