Abstract
The applicability of the strap-down automatic vertical drilling system with anti-deviation and well straightening features was examined by field tests. The drill string contact-impact and its nonlinear characteristics were studied based on Lagrange explicit algorithm and parallel computing method. A field test was conducted by using a strap-down automatic vertical drilling system, and the contact-impact between drill string and borehole was analysed by using numerical method. The actual well deviation and azimuth were obtained along with the stress of the drill string and compared with their counterparts in the target well. Results showed that the strap-down automatic vertical drilling system was highly practical, and the actual well deviation and azimuth were almost similar with the target well. Parallel computing method greatly reduced numerical simulation time, and parallel speedup ratio increased with the increase of parallel node numbers. Conversely, parallel efficiency decreased with the increase of parallel node numbers. Drill string bending stress wave propagation was the root cause of alternating stress. The lagging effect also exists in the impact of drill string.
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