Abstract
Research on drilling response characteristics of two-wing polycrystalline diamond compact (PDC) bit in different rocks is an important way to further understand the mechanism of rock-breaking, improve drilling efficiency, and identify the rock formation interfaces in coal mines. However, the research on the drilling response characteristics of two-wing PDC bits is relatively rare due to the harsh environment in coal mines. In this study, a series of two-wing PDC bits were used to drill in sandstone and sandy mudstone to study the response characteristic of sound pressure level, displacement curves, longitudinal vibration, and rock cuttings size. The collected data were processed by MATLAB based on the 3σ principle. The cuttings were collected through a newly designed cuttings collection device. The experimental results show that the sound pressure level and the longitudinal vibration are larger when drilling in the higher strength sandstone, which is opposite to the cuttings particles and the penetration rate. The reduction of drilling efficiency is more obvious when drilling in sandstone with a worn bit. Therefore, drilling efficiency can be improved by optimizing the bit structure so that the broken rock blocks flow out of the anchor holes as early as possible to avoid being broken into cuttings.
Highlights
Polycrystalline diamond compact (PDC) bits are widely used to drill various formations in oil and gas, mining engineering, and other fields
The rock-breaking mechanism of cross-cutting PDC bit was investigated by laboratory experiments and numerical simulation [2]
Two-wing PDC bits of different diameters were used to drill in sandstone and sandy mudstone, and the sound pressure level, displacement, longitudinal vibration, and rock cuttings during the drilling process were analyzed and discussed
Summary
Polycrystalline diamond compact (PDC) bits are widely used to drill various formations in oil and gas, mining engineering, and other fields. It is crucial to study the rock-breaking mechanism of PDC bits. The rock-breaking mechanism of cross-cutting PDC bit was investigated by laboratory experiments and numerical simulation [2]. The rock-breaking mechanism under single-tooth impact was studied by theoretical derivation and numerical simulation [3]. Several studies [4,5,6] have been conducted to understand the drilling response characteristics of wear PDC bits. A close relationship between the bit wear condition and bit torque was found by drilling tests conducted in the laboratory using Percussion bits, PDC bits, roller cone bits, and various rocks [5]. The sound pressure level, longitudinal vibration, and cuttings particle characteristics of worn bits when drilling in rock formations of different strengths have not been properly studied yet. (a) 3D model established (b) Single cutting wing model (a) 3D modFeilgeustraeb2li.shTehde structure model of the two(-bw) iSninggPleDcCutbtint.g wing model
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