Shiyou jixie (Jun 2025)
Numerical Simulation on Cutting and Breaking of Heterogeneous Conglomerate by Special-Shaped PDC Cutter
Abstract
When the PDC bit is used to drill conglomerate formations， the frequent impact loads reduce the expected life of PDC cutter， leading to frequent bit changes and ultimately affecting drilling efficiency. Special-shaped cutter can change the impact situation on the cutter surface， so choosing an impact-resistant cutter surface is one of the effective methods to deal with such formations. To study the performance of PDC cutter with different structures in cutting conglomerate， the conglomerate cores taken from deep formation of the Junggar Basin were selected for analysis. Based on a finite element model of heterogeneous conglomerate， the parameters of the conglomerate model were calibrated through uniaxial compression test， and rock cutting and breaking simulation of special-shaped cutter was carried out. Moreover， the cutting effects of 12 types of PDC cutters were discussed under the same rake angle and cutting depth， and the cutting force fluctuation and rock-breaking specific energy of them were compared. The study results show that although the average cutting forces of axe-shaped cutter and three-plane cutter are relatively large， the overall fluctuations are more stable. The cutting force fluctuations of planar cutter， concave cutter， convex cutter and hyperboloidal cutter are relatively large， and the cutter surfaces are subjected to significant impact. The rock-breaking specific energy determines the rock breaking efficiency of the cutter， by means of comparing the values， the rock-breaking specific energy of hyperboloidal cutter is the smallest， while that of wedge-shaped cutter is the largest. Without considering the rigidity of PDC cutter， by means of comparing cutting force fluctuation and rock-breaking specific energy， the axe-shaped cutter and three-plane cutter are the better choices among all types of PDC cutters. The study results provide some reference for the cutter shape selection of PDC bit when drilling conglomerate formations.
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