Drill pipe buckling affects the industry in many operational aspects, like motor sliding problems, liner running, or weigh transfer for downhole equipment activation.

The authors believed the existing non rotating buckling theories applied in drilling software needed challenging, by physically measuring buckling in a realistic setup of well geometry and drill string sizes, and comparing the results with the buckling theories.

The tests were performed in a 2020 mMD research well, with a build-up and 60° tangent geometry. Various configurations of a tapered string with 5" and 3 1/2" drill pipe, as well as drill collars were used.

A novel approach was using a high accuracy continuous gyro to measure the string geometry changes (i.e. buckling), and both downhole and topside tension devices were applied to measure weight transfer.

Several datasets recording buckling and weight transfer were obtained; the gyro measurements of drill pipe geometry changes clearly demonstrated the onset and type of drill pipe buckling.

Weight transfer was also measured under different buckling states and demonstrated that lockup occurs before reaching a helically buckled state. This might alter operational practice regarding design of running strings.

The results have been compared with predictions from buckling models, and necessary model enhancements suggested.

The work has potential to improve buckling and weight transfer models. The potential outcome will be more accurate prediction for sinusoidal and helical buckling, and their effects on weight transfer. Ultimately, this will lead to better decision making and understanding in drilling and completion operations.

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