	US 12,241,371 B1
	Integrated mining method of coal breaking, coal extraction and water circulation in U-well and system thereof
Yifan Zeng, Beijing (CN); Donghui Yang, Beijing (CN); Qiang Wu, Beijing (CN); Hao Li, Beijing (CN); Junhao Ren, Beijing (CN); Zeyang Liu, Beijing (CN); Jia Zhao, Beijing (CN); and Zilong Yuan, Beijing (CN)
Assigned to CHINA UNIVERSITY OF MINING AND TECHNOLOGY, BEIJING, Beijing (CN)
Filed by CHINA UNIVERSITY OF MINING AND TECHNOLOGY, BEIJING, Beijing (CN)
Filed on Jul. 1, 2024, as Appl. No. 18/760,362.
Claims priority of application No. 202311685439.8 (CN), filed on Dec. 8, 2023.
Int. Cl. E21C 25/60 (2006.01); E21C 41/18 (2006.01)

CPC E21C 41/18 (2013.01) [E21C 25/60 (2013.01)]

6 Claims

4. A coal mining system in a U-well, comprising: a first ground facility unit, a second ground facility unit, a jet unit and an extraction unit; wherein, the coal mining system is disposed in the U-well; the U-well comprises: a coal breaking section, an extraction hole and a coal breaking hole; the coal breaking section is a horizontal drilling section; wherein, the jet unit is disposed on a side of the coal breaking section close to the extraction hole through the coal breaking hole; the extraction unit is disposed on a side of the coal breaking section close to the extraction hole through the extraction hole; the first ground facility unit connects to the jet unit; the second ground facility unit connects to the extraction unit; the coal breaking section comprises a plurality of sub-segments; initial positions of the jet unit and the extraction unit are on a side of the coal breaking section adjacent to the extraction hole; terminal positions of the jet unit and the extraction unit are on a side of the coal breaking section adjacent to the coal breaking hole;

the first ground facility unit, the jet unit, the extraction unit, and the second ground facility unit are configured to perform following operations iteratively until the extraction of the coal breaking section is complete:

the first ground facility unit is configured to transport jet fluid pressurized to the jet unit;

the jet unit is configured to break a coal seam in one sub-segment of the plurality of sub-segments at a current position according to a preset breaking angle and a preset breaking radius to obtain broken cinders; wherein, the jet unit comprises: a jet lance; wherein, the jet lance is provided with a spray nozzle; a spray direction of the spray nozzle is at an acute angle to a directional drill pipe of the extraction unit;

the extraction unit is configured to extract a coal-water mixture directionally according to a preset extraction rate; wherein, the coal-water mixture comprises: the broken cinders and the jet fluid;

the second ground facility unit is configured to receive the coal-water mixture; and

in response to determining that an extraction of the sub-segment is complete, the jet unit and the extraction unit is configured to move to a next sub-segment using powers provided by the first ground facility unit and the second ground facility unit; wherein,

determining the preset extraction rate of the extraction unit;

calculating an injection rate of the jet fluid according to the preset extraction rate of the extraction unit; and

injecting, by the jet unit, a stream of the jet fluid into the sub-segment according to the injection rate of the jet fluid, the preset breaking angle and the preset breaking radius to break the coal into the broken cinders; wherein,

the injection rate of the jet fluid is calculated according to following formulas:

wherein, k represents a consistency coefficient; Q1 represents the injection rate of the jet fluid; Q2 represents a loss rate of the jet fluid; Q3 represents the preset extraction rate of the extraction unit; r represents a radial loss distance; m represents a flow pattern index; ω represents a fracture opening; p represents a pressure of the jet fluid; and τ_yrepresents a shear stress.