PDC Bit Rock Drillability Measurement And Classification Method Research

To improve the practicability of the testing and grading principle of rock drillability, researches in this paper mainly studied the unreasonable structures of the conventional testing PDC micro-bit and broadened the evaluation range of rock drillability. First, a great amount of experiments are conducted on rock drillability with different rocks and micro-bits. Analyzing on the experiment results discloses the influencing laws of different structures and testing situations on rock drillability, thus revealing an advanced rock drillibility testing principle for the PDC bit. Furtherly, with improved testing conditions, an advanced rock drillability grading principle is put forward in this paper. Analyzing with the geometry theory of the PDC bit, problems are found that interference occurs between cutters of the micro-bit and the bottom-hole rock in the drilling process, which will greatly influence the accuracy of rock drillability testing and grading. Accordingly, influences of cutter's back rake angle, side rake angle and thickness on the interference phenomenon are respectively studied, accordingly, improving solutions for structure parameters of the bit are put forward to solve the problems.Researches in this paper mainly studied:(1) Analyzed and concluded the existing problems in existing drillability grading standards.(2) Carried out a series of drillability experiments with micro-bits, and furtherly analyzed the influences of operational parameters, cutter structures and rock features on the rock drillability, accordingly, improved the drillability testing methods for PDC bits.(3) Through analyzing the drillability testing results, a new drillability grading method is put forward.(4) With related design principles of PDC bits, influences of cutter's back rake angle, side rake angle and thickness on the interference phenomenon are respectively studied to achieve an improving plan for the structures of the existing testing micro-bits.Through studying on the drillability testing experiments, key factors affecting rock drillability grading are revealed, furtherly, a scientific testing and grading principle of rock drillability for PDC bits is put forward in this paper, which provides valuable references for the following revising of the principle.