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<p>Particle impact drilling (PID) technology is a breakthrough for achieving low mechanical drilling speeds in hard and abrasive formations. A design method for a new type of PID bit, which is a key component of the PID system, was proposed. The newly designed PID bit can continuously excavate rock formations using only the impingement of the particle discharge streams. The rock-breaking experiments show that the designed PID bit transforms the hydraulic power to the momentum of the particles, and the emergence angles of multiple-particle water jets can be continuously adjusted to cover the entire borehole bottom to produce an integral wellbore. The design method is suitable for designation PID bits of different sizes. Single-nozzle and multi-nozzle combination rock-breaking experiments with granite and conglomerate sand rock representing hard and abrasive formations, respectively, were conducted under confining pressure. The experiments showed that the optimum dimensionless standoff distance was 7.5, and the optimum range of emergence angle was 9–20°. A strong relationship exists between the borehole bottom profile produced by multiple tilted particle water jets and rock strength. The borehole bottom profile is more sensitive to the emergence angle of particle water jets with greater rock strength. The optimized emergence angles of the designed triple-nozzle PID bit were 18.8, 10.6, and 11.3° while breaking granite. Meanwhile, the borehole bottom profile produced, while breaking conglomerate sand rock was insensitive to the emergence angles of the nozzles. The borehole bottom profile and rock-breaking efficiency were unaffected by the PID bit rotation rate. The emergence angle optimized to break hard formations is also suitable for rock-breaking abrasive formations. The maximum penetration rate obtained for breaking granite with the designed PID bit was 4.0&#xa0;m/h without any mechanical auxiliaries, while the maximum penetration rate for sand conglomerate rock exceeded 4.0&#xa0;m/h. A comprehensive rock-breaking experiment shows that the designed PID bit produced an integral borehole using different forward speeds without contact with the rock and drilling pressure. The produced borehole profile was smooth and had a borehole enlargement rate of 3.3%–8.9%. A borehole profile without any neck or borehole space provides continuous drilling with the PID bit.</p>

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Optimization Design of Particle Impact Drilling Bit and Rock-Breaking Experiment

  • 期刊论文

  • 发表日期：

    2025年10月6日

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  • Weidong Zhou,
  • Luopeng Li,
  • Zizhen Wang,
  • Fangxiang Wang,
  • Guichun Chen,
  • Yincang Liu

摘要

Particle impact drilling (PID) technology is a breakthrough for achieving low mechanical drilling speeds in hard and abrasive formations. A design method for a new type of PID bit, which is a key component of the PID system, was proposed. The newly designed PID bit can continuously excavate rock formations using only the impingement of the particle discharge streams. The rock-breaking experiments show that the designed PID bit transforms the hydraulic power to the momentum of the particles, and the emergence angles of multiple-particle water jets can be continuously adjusted to cover the entire borehole bottom to produce an integral wellbore. The design method is suitable for designation PID bits of different sizes. Single-nozzle and multi-nozzle combination rock-breaking experiments with granite and conglomerate sand rock representing hard and abrasive formations, respectively, were conducted under confining pressure. The experiments showed that the optimum dimensionless standoff distance was 7.5, and the optimum range of emergence angle was 9–20°. A strong relationship exists between the borehole bottom profile produced by multiple tilted particle water jets and rock strength. The borehole bottom profile is more sensitive to the emergence angle of particle water jets with greater rock strength. The optimized emergence angles of the designed triple-nozzle PID bit were 18.8, 10.6, and 11.3° while breaking granite. Meanwhile, the borehole bottom profile produced, while breaking conglomerate sand rock was insensitive to the emergence angles of the nozzles. The borehole bottom profile and rock-breaking efficiency were unaffected by the PID bit rotation rate. The emergence angle optimized to break hard formations is also suitable for rock-breaking abrasive formations. The maximum penetration rate obtained for breaking granite with the designed PID bit was 4.0 m/h without any mechanical auxiliaries, while the maximum penetration rate for sand conglomerate rock exceeded 4.0 m/h. A comprehensive rock-breaking experiment shows that the designed PID bit produced an integral borehole using different forward speeds without contact with the rock and drilling pressure. The produced borehole profile was smooth and had a borehole enlargement rate of 3.3%–8.9%. A borehole profile without any neck or borehole space provides continuous drilling with the PID bit.