Using hydraulic fracturing to control caving of the hanging roof during the initial mining stages in a longwall coal mine: a case study

Huang, Bingxiang; Cheng, Qingying; Zhao, Xinglong; Xue, Weichao; Scoble, Malcolm J.

doi:10.1007/s12517-018-3969-5

Cited by 24 publications

(17 citation statements)

References 4 publications

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“…Since its successful application in Kansas in 1947, hydraulic fracturing has been widely used in oil-gas field development, mine roof control, and other related fields and has achieved good application results [1][2][3][4]. The key to hydraulic fracturing design is the morphology of hydraulic fractures [5].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Fracturing Effect Induced by the Disturbing Stress of Hydrofracturing Using the Bonded-Particle Model

Zhang

Huang

2021

Geofluids

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Hydraulic fracturing applications have shown a stress disturbance effect during hydraulic fracture propagation, which is often ignored. Using laboratory and discrete element numerical simulation tests, hydraulic fracture propagation under this stress disturbance is systematically studied. The results show that during hydraulic fracturing, the bedding plane is damaged by the stress disturbance, forming a bedding fracture zone (BFZ). The nonlinear fracture characteristics of the formation process of the disturbed fracture zone are revealed, and two indexes (the number of fractures in the disturbed fracture zone and the size of the disturbed fracture zone) are proposed to evaluate the fracturing effect of the stress disturbance. Based on these indexes, multifactor sensitivity tests are conducted under different geological conditions and operational factors. When the principal stress ( σ 1 ) difference is large, the number of hydraulic fractures gradually decreases from many to one, and the direction of the hydraulic fractures gradually approaches the vertical direction of σ 3 , but the change in the in situ stress condition has no obvious effect on the stress disturbance effect. The weaker the bonding strength of the bedding plane, the more significant the stress disturbance effect is, and the easier it is for the fractures to expand along the bedding plane. With increasing injection rate, the stress disturbance effect first increases and then decreases, and the hydraulic fracture propagates from along the bedding plane to cross the bedding plane. With increasing relative distance between the injection hole and bedding plane, the stress disturbance effect presents a linearly increasing trend, and the hydraulic fractures along the bedding planes extend. Based on the experimental results, the relationship between the fracturing effect of the stress disturbance and the extension mode of the hydraulic fracture is determined, and an optimization method for hydraulic fracturing in composite rock reservoirs is given. The research results can provide a theoretical basis for controlling the formation of complex fracture networks in composite rock reservoirs.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Fracturing Effect Induced by the Disturbing Stress of Hydrofracturing Using the Bonded-Particle Model

Zhang

Huang

2021

Geofluids

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“…There are two types that coal seam porosity is affected by pulse wave. One is the expansion of the original pore, and the other is the new pores formed by the erosion of mineral crystal embedded in the coal body [18]. Pulse pressure and Pulsed hydraulic fracturing is one kind of hydraulic fracturing that a pulse pump is utilized to pump water into the coal-rock mass with a pulse pumping rate.…”

Section: Introductionmentioning

confidence: 99%

Combination of Pre-Pulse and Constant Pumping Rate Hydraulic Fracturing for Weakening Hard Coal and Rock Mass

et al. 2020

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The weakening of hard coal–rock mass is the core common problem that is involved in the top coal weakening in hard and thick coal seams, the hard roof control during the initial mining stage in the longwall mining face, and the hanging roof control in the gob of non-coal mine. Based on the characteristics of pulse hydraulic fracturing and constant pumping rate hydraulic fracturing, a weakening method for hard coal–rock mass by combining pre-pulse and constant pumping rate hydraulic fracturing is proposed. A complete set of equipment for the combined pulse and constant pumping rate hydraulic fracturing construction in the underground coal mine is developed. The pulse and constant pumping rate hydraulic fracturing technology and equipment were applied in the top coal weakening of the shallow buried thick coal seam. Compared with no weakening measures for top coal, the average block size of the top coal caving was reduced by 42% after top coal hydraulic fracturing. The recovery rate of the top coal caving mining face reached 85%, and it increased by 18% after hydraulic fracturing.

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“…He et al [18] proposed the "three-control" theory including roof, rib-to-rib, and floor angles. Huang et al [19,20] proposed that the basic roof of the cutting roadway under directional hydraulic fracturing drilling can control the deformation.…”

Section: Introductionmentioning

confidence: 99%

Research on Key Technologies of Floor Heave Control in Soft Rock Roadway

Shi

Zhang²,

Wang

2020

Advances in Civil Engineering

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Aiming at the floor heave of transportation concentrated roadway on the West Wing (TCRWW) of No. 1 Coal Seam in Danhou Mine, it affects underground coal transportation and mine safety production. First, the lithology and structure of the roadway floor were sampled and tested, and it was found that it contained clay minerals with high hydrophilicity. Secondly, starting from the mechanical mechanism of the roadway floor, a mechanical model of the roadway floor is established. By increasing the floor anchoring layer thickness m1, the floor deformation can be effectively controlled to guarantee the stability of the surrounding rock of the roadway. Thirdly, the FLAC3D numerical simulation analysis of the roadway deformation under the existing support scheme of the roadway is consistent with the measured deformation results on-site, thereby revealing that the existing support scheme and parameters are not reasonable. Finally, the unreasonable support scheme and parameters of the existing roadway were disclosed, and an antifloor arch structure was proposed: “quicklime bottom paving + prestressed anchor cable + concrete arc beam + metal mesh + C20 high-strength concrete filling.” This floor treatment plan is adopted for the industrial verification of the test section of TCRWW. Engineering practice shows that the optimized roadway support scheme has a better effect on the deformation control of the roof-to-floor and rib-to-rib, thereby effectively ensuring safe and efficient production in the mine.

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Using hydraulic fracturing to control caving of the hanging roof during the initial mining stages in a longwall coal mine: a case study

Cited by 24 publications

References 4 publications

Investigation of the Fracturing Effect Induced by the Disturbing Stress of Hydrofracturing Using the Bonded-Particle Model

Investigation of the Fracturing Effect Induced by the Disturbing Stress of Hydrofracturing Using the Bonded-Particle Model

Combination of Pre-Pulse and Constant Pumping Rate Hydraulic Fracturing for Weakening Hard Coal and Rock Mass

Research on Key Technologies of Floor Heave Control in Soft Rock Roadway

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