Study on speed-up of PDC bit in deep highly abrasive formations of East China Sea

Abstract:

The H3 Formation of the HG Group in the ZZ Block， East China Sea， is characterized by the development of thick， highly abrasive sandstone sequences. This challenging geological condition leads to a low rate of penetration （ROP）， short footage per bit， extended drilling cycles， and consequently high operational costs. To improve drilling efficiency and shorten the drilling cycle， this study conducted systematic field trials based on a comprehensive analysis of formation characteristics and historical bit performance records， investigating the impact of bit size， cutter layout parameters， crown profile selection， and PDC cutter type on drilling performance. The results indicate that within the H3 Formation， ?215.9 mm bits demonstrate significantly superior performance in both ROP and efficiency compared to ?311.15 mm bits. PDC bits with a deep inner cone crown profile exhibit stronger aggressiveness and achieve a higher ROP. Furthermore， axe-shaped cutters experience significantly less wear compared to conventional flat-faced cutters， effectively increasing footage per bit. Additionally， rotating cutters substantially improve cutting edge utilization and heat dissipation， enabling a breakthrough of 1250 m in a single run. These findings provide an effective technical solution for enhancing drilling efficiency in the highly abrasive formations of this block， offer vital technical support for oil and gas exploration and development in similar offshore formations， and hold significant importance for safeguarding national energy security.