Field application of directional hydraulic fracturing technology for controlling thick hard roof: a case study

Roof management in coal mines is a critical technology challenge to realize safe production. Dynamic disasters can be induced by a sudden collapse of the roof when encountering a thick hard roof above a coal seam. To solve this problem, directional hydraulic fracturing technology was utilized in the...

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Bibliographic Details
Published inArabian journal of geosciences Vol. 14; no. 6
Main Authors Sun, Yongxin, Fu, Yukai, Wang, Tao
Format Journal Article
LanguageEnglish
Published Cham Springer International Publishing 01.03.2021
Springer Nature B.V
Subjects
Coal
Coal mines
Disasters
Earth and Environmental Science
Earth science
Earth Sciences
Grooves
Hydraulic fracturing
Limestone
Orifices
Original Paper
Pressure
Roofs
Technology
Weighting
Coal mining
Stress distribution
Directional hydraulic fracturing
Thick hard roof
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Summary:Roof management in coal mines is a critical technology challenge to realize safe production. Dynamic disasters can be induced by a sudden collapse of the roof when encountering a thick hard roof above a coal seam. To solve this problem, directional hydraulic fracturing technology was utilized in the coal mine WP with a thick hard limestone roof. To effectively cut artificial transverse grooves in a fracturing hole in rock with a high strength, the KZ54-type transverse grooving bit was developed. Furthermore, the developed small-aperture high-pressure span-type expansion sealer can effectively seal the holes and ensure hydraulic crack expansion. The field observations show that the radii of extension of the hydraulic fractures were 15–20 m and that the rupture pressure at various depths in the holes ranged from 9 to 32 MPa from the orifice to the bottom of the hole. The deeper the fracturing location in the hole, the higher the fracturing pressure was. The principal stresses in front of the working face and the resistance forces of the hydraulic supports at the working face were monitored when the working face advanced. The first weighting of the roof decreased from 38.3 to 26 m, and the periodic weighting decreased from 26 to 13.7 m. Hydraulic fracturing reduced the resistance force of the supports at the working face.
ISSN:1866-7511
1866-7538
DOI:10.1007/s12517-021-06790-4