Title:
CRYOGENIC FRACTURING AND ROOF CAVING METHOD FOR HARD ROOF IN GOAF OF COAL MINE
Document Type and Number:
WIPO Patent Application WO/2021/184694
Kind Code:
A1
Abstract:
A cryogenic fracturing and roof caving method for hard roof in goaf of a coal mine, applicable to the technical field of enhanced fracturing of roof in goaf of a coal seam. Digital display thermometers (1), temperature sensors (3), water injection pipes, cryogenic fluid freezing pipes, capsule borehole sealing devices, a high-pressure water injection system (13), and a cryogenic fluid tank (14) are used for constructing multiple fracturing boreholes (9) and one empty hole (16) on hard roof of goaf in sequence; the spiral cryogenic fluid freezing pipes, the water injection pipes, and the capsule borehole sealing devices are connected and delivered to the multiple fracturing boreholes, the capsule borehole sealing devices are used for performing high-pressure borehole sealing, cylindrical borehole expansion sections (8) at openings of the fracturing boreholes are frozen to form self-borehole sealing structures, then the multiple fracturing boreholes are frozen, and the roof of the coal seam is fractured by means of water-ice phase transition. When values of the temperature sensors all increase to 3°C or above, freezing is repeated, forming a cycle of frost heaving-thawing-frost heaving for fracturing. The use of a cryogenic fluid for water-ice phase transition produces an expansion rate of 9.1% to fracture the hard roof of a coal seam. The method is simple, convenient to operate, low in cost, simple to operate, and good in fracturing effect.
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Inventors:
ZHAI CHENG (CN)
ZHENG YANGFENG (CN)
XU JIZHAO (CN)
CONG YUZHOU (CN)
SUN YONG (CN)
YAO YANBIN (CN)
TANG WEI (CN)
LI YUJIE (CN)
ZHENG YANGFENG (CN)
XU JIZHAO (CN)
CONG YUZHOU (CN)
SUN YONG (CN)
YAO YANBIN (CN)
TANG WEI (CN)
LI YUJIE (CN)
Application Number:
PCT/CN2020/113348
Publication Date:
September 23, 2021
Filing Date:
September 04, 2020
Export Citation:
Assignee:
ZHAI CHENG (CN)
International Classes:
E21C41/18; E21B43/26; E21C37/14
Foreign References:
| CN111173513A | 2020-05-19 | |||
| CN106014408A | 2016-10-12 | |||
| CN107476807A | 2017-12-15 | |||
| CN105134284A | 2015-12-09 | |||
| CN109915199A | 2019-06-21 | |||
| CN104213921A | 2014-12-17 | |||
| US9605513B1 | 2017-03-28 | |||
| KR20140046202A | 2014-04-18 |
Attorney, Agent or Firm:
JW IP LAW FIRM (CN)
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