Design and numerical analysis of a large‐diameter air reverse circulation drill bit for reverse circulation down‐the‐hole air hammer drilling

Reverse circulation down‐the‐hole (RC‐DTH) air hammer drilling is a fast and cost‐effective method for hard rock drilling. As the air RC drill bit is the heart for RC‐DTH air hammer drilling system to form the reverse circulation, a large‐diameter RC drill bit was innovatively designed and numerical...

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Bibliographic Details
Published in:Energy science & engineering 2019-06, Vol.7 (3), p.921-929
Main Authors: Zhang, Xinxin, Luo, Yongjiang, Gan, Xin, Yin, Kun
Format: Article
Language:English
Subjects:
Air flow
Circulation
Compressed air
Design
Drill bits
Drilling
Elevation angle
Field tests
Flow rates
Flow velocity
Mass flow rate
Nozzles
Numerical analysis
Optimization
RC drill bit
RC‐DTH air hammer
reverse circulation
Rocks
Rotary drilling
Suction
suction ability
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Summary:Reverse circulation down‐the‐hole (RC‐DTH) air hammer drilling is a fast and cost‐effective method for hard rock drilling. As the air RC drill bit is the heart for RC‐DTH air hammer drilling system to form the reverse circulation, a large‐diameter RC drill bit was innovatively designed and numerically optimized with respect to the suction ability. Results show that increasing the suction‐nozzle elevation angle and deflection angle can improve the drill bit suction ability. The drill bit performance reaches its optimal state when the air flow rate was about 1.205 kg/s, thereafter it exhibits a reverse variation trend with the increase in air mass flow rate. The optimum diameter of the suction nozzles is 20 mm for the drill bit studied in this work. The RC drill bit with outer diameter of 665 mm and RC‐DTH air hammer with outer diameter of 400 mm were manufactured and a field trial was conducted. Field test results show that the penetration rate using the RC‐DTH air hammer drilling method is more than twice the conventional rotary drilling method. This drilling approach poses a great potential for the large‐diameter hard rock drilling applied in the upper portions of a well bore above the potential producing reservoir formation for land oil and gas drilling, geothermal drilling and relevant field drilling operations. Reverse circulation down‐the‐hole air hammer drilling is a fast and cost‐effective method for hard rock drilling. A large‐diameter RC drill bit was innovatively designed and numerically optimized with respect to the suction ability.
ISSN:2050-0505
2050-0505
DOI:10.1002/ese3.321