Development and application of PDC bits for Xujiahe difficult drilling formations in Xinchang-Hexingchang Area

Abstract:

Aiming at the rock-breaking challenges of the Xujiahe Formation in the Xinchang-Heqingchang Block， such as high formation hardness， poor drillability， strong abrasiveness， and significant heterogeneity， this study established a drilling resistance characteristic parameter profile of the Xujiahe Formation. It conducted an analysis of the engineering requirements for the target interval and typical bit failure modes. Combined with research on the rock-breaking characteristics of different types of cutter， the study optimized the cutter arrangement pattern and proposed a “circular + wedge-shaped” double-row planar mixed cutter arrangement structure. Through bit force analysis， the crown profile， blade structure， and gauge protection structure were optimally designed to form a cutting structure with “high guidance + force balance stability”. Finally， a customized PDC bit for the difficult-to-drill formations of the Xujiahe Formation was developed. Field application results show that the average rate of penetration （ROP） reaches 4.88 m/h， increased 41%； the average run length reaches 347.16 m， increased 104%. This provides a new technical means for breaking through the drilling speed bottleneck of the tight sandstone gas reservoir in the second member of the Xujiahe Formation in the Xinchang-Hexingchang Block.