Rock-Breaking Properties of Multi-Nozzle Bits for Tree-Type Drilling in Underground Coal Mines

Yiyu Lu, Songqiang Xiao, Zhaolong Ge, Zhe Zhou and Kai Deng
Additional contact information
Yiyu Lu: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Songqiang Xiao: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Zhaolong Ge: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Zhe Zhou: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Kai Deng: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

Energies, 2016, vol. 9, issue 4, 1-17

Abstract: Tree-type drilling is a new technique for drilling radial tree-type boreholes in coal seams in underground mines using water jets to break the coal. The aim is to drain gas from the coal seams in larger quantities and from larger areas than can be done by conventional gas drainage using single boreholes. The self-propelled drill bit is the most important component for this technique. The bit generates a self-propelling force to move forward, break coal, and form a borehole. This paper investigates the relationships between the physical parameters of the forward nozzles in the bit and the diameter and shape of the borehole drilled. The effect of different physical parameters on the rock-breaking efficiency is studied by conducting drilling experiments. The results show that the size, orientation and number of the nozzles significantly affect the rock-breaking efficiency of the bit. To obtain a better rock-breaking efficiency under the experimental conditions used for this paper, the axial angle for forward nozzles should be 15°, the radial angle 90°, and nozzles should be arranged 2.1 mm from the center of a 12 mm drill bit. The experimental results provide a reference for the design of multi-nozzle bits for many applications such as radial jet drilling (RJD) and bent pipe cleaning.

Keywords: coalbed methane (CBM) drainage; tree-type drilling; water jet; multi-nozzle bits; rock-breaking properties (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

Downloads: (external link)
https://www.mdpi.com/1996-1073/9/4/249/pdf (application/pdf)
https://www.mdpi.com/1996-1073/9/4/249/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:9:y:2016:i:4:p:249-:d:66755

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().