Evaluating the maximum rate of penetration for drilling borehole in soft coal seam

Yang, Shuo; Wen, Guangrui; Yan, Fazhi; Zhang, Mingjie; Zhao, Xusheng

doi:10.1002/ese3.724

Cited by 8 publications

(4 citation statements)

References 37 publications

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“…After that, the air composite directional drilling technology and equipment are proposed to achieve the advanced regional pre-extraction for gas control in soft coal seams, which plays an obvious guiding role in field application . By using composite directional and slag discharge technology, a technical scheme of directional drilling in soft coal seams was proposed, which provides a new technical means for progressive gas extraction . The advantages of the hydraulic fracturing technology and directional drilling technology were combined to form the roof comb-hole hydraulic fracturing technology, which proves good applicability in the field of gas enhanced extraction in soft coal seams .…”

Section: Introductionmentioning

confidence: 99%

“… 13 By using composite directional and slag discharge technology, a technical scheme of directional drilling in soft coal seams was proposed, which provides a new technical means for progressive gas extraction. 14 The advantages of the hydraulic fracturing technology and directional drilling technology were combined to form the roof comb-hole hydraulic fracturing technology, which proves good applicability in the field of gas enhanced extraction in soft coal seams. 15 Numerical simulation on the stability of borehole wall was carried out to estimate the mechanical parameters of soft coal seams by Hoek–Brown criterion, and reveal the stress and displacement distribution around the borehole wall.…”

Section: Introductionmentioning

confidence: 99%

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Gas Migration around Large Diameter Borehole with the Protective Screen Pipe in Fractured Soft Coal Seam

Ren

Wang

2023

ACS Omega

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Large diameter borehole drilling in fractured soft coal seam may lead to problems such as drilling blockage, perforation, and hole collapse. The protective screen pipe in the drilling hole can support the damaged coal, prevent the drilling blockage, and improve the coal permeability. The mathematical model of gas drainage by large diameter borehole in fractured soft coal seam was established. Taking the 3205 working face in Shanxi Fenxi Zhongxing Coal Mine as the background, the numerical simulation was carried out by importing the mathematical model into COMSOL Multi-physics software to study the gas migration law around large boreholes with protective screen pipe in fractured soft coal seam. The results show that the gas flow velocity in section A of the borehole and pipe is between 0 and 0.25 m/s, and the gas flow velocity in the borehole is smaller than that in the pipe and screen hole. The gas velocity in the borehole is lower than that in the protective screen pipe. In the large diameter borehole, the protective screen pipe can support the collapsed coal and prevent the borehole blockage. The free gas in the borehole can be quickly extracted out through the screen holes, which ensures the gas extraction efficiency. The results provide a guidance for promotion and application of the technology of large diameter borehole with protective screen pipe in field.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gas Migration around Large Diameter Borehole with the Protective Screen Pipe in Fractured Soft Coal Seam

Ren

Wang

2023

ACS Omega

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“…Te three-soft coal seam [1][2][3][4] refers to the coal seam with a soft roof, soft foor, and soft coal quality. Te following requirements should be met: (1) According to [5,6], coal seams with a sturdiness coefcient f < 1 are classifed as weak coal seams (Platt's coefcient f, also known as the rock sturdiness coefcient and fastening coefcient, is 1/10 of the ultimate uniaxial compressive strength of rocks and is dimensionless); (2) the uniaxial compressive strength of direct roof rocks of the coal seam σ ≤ 25 MPa or joint spacing d ≤ 60 cm; (3) the uniaxial compressive strength of the coal seam foor σ ≤ 25 MPa. Te roof, coal, and foor of the lower three-soft-protected coal seams form a TS-RCR structure in the pressure-relief mining process of the close-distance seam group.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Damage and Crack Evolution Characteristics of TS-RCR Structural Bodies under Cyclic Loading and Unloading

Xie,

Chen,

Fang

et al. 2023

Advances in Civil Engineering

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Four representative TS-RCR (three-soft rock-coal-rock) structural bodies were selected according to the lithofacies analysis of coal measures in the Xiangshui Coal Mine, Guizhou, China, to analyze the mechanical properties, internal structure damage characteristics, and crack evolution law of the TS-RCR structural body composed of a soft roof, a soft floor, and soft coal seams. The mechanical model of the TS-RCR structural body was proposed. (1) The stress-strain curves of TS-RCR structures with different lithologies under cyclic loading and unloading show a change rule of sparsity, density, and sparsity with the increased cycles. The deformation of TS-RCR structures under cyclic loading and unloading can be divided into four stages. When the height ratio of the TS-RCR structural body was the same, the higher the strength of the upper and lower rocks, the more cycles the TS-RCR structural body had, and the denser the cyclic loading and unloading curve. On the contrary, the fewer cycles the TS-RCR structural body had, the sparser the cyclic loading and unloading curve. (2) The T2 (transverse relaxation time) spectrum curves of the structural bodies were monitored at about 1 and 10 ms, and two obvious peaks were detected, indicating micropores and mesopores with a large volume in the structural body. Signal intensity increased at the relaxation time of 1 ms, decreased at 10–100 ms, and increased slightly at 100–1000 ms. The pore structure of the structural body with different lithologies changed significantly with the increased cycle number. (3) The damage and failure process of the structural body was roughly divided into three periods according to the time-history analysis of acoustic-emission AF (the ratio of acoustic-emission ringing count to duration) of the structural body: the active period with a relatively low AF value (AF < 60 kHz) in the 1st-2nd cycles; the rising period with a relatively stable increase of the AF value in the 3rd-4th cycles; and the explosive period with a relatively high AF value (AF ≥ 60 kHz) in the 5th cycles. According to the relationship between the RA (the ratio of the rise time to the amplitude of the acoustic-emission-detection wave) value and time, the evolution law of the RA value and AF value of structures with different lithologies is similar in different periods under cyclic loading and unloading.

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“…Chae et al [8] and Zhou and Yan [9] studied the influence of borehole size to the gas flow. Yang et al [10] established a simplified ROP model for soft coal seams to improve drilling efficiency. e results of Shakib et al [11] can be used to support the improved directional drilling system design.…”

Section: Introductionmentioning

confidence: 99%

Study on Key Parameters of Directional Long Borehole Layout in High‐Gas Working Face

Yan

Wang

Fan

et al. 2021

Shock and Vibration

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This research aims to obtain a new way based on the directional long borehole layout to investigate the gas migration behavior of coal bed methane. In view of the study of the oil-type gas reservoir and the influence range of mining on the working face in the surrounding rock, the paper puts forward the optimization method of the directional long borehole layout of the surrounding rock and the method of the borehole layout with comprehensive consideration of the influence of mining on the failure of the roof and floor and the distribution of surrounding rock gas-bearing reservoirs. The test results showed that the layout horizon of the directional long boreholes is determined, and the layout was within the height range of 20–40 meters, clarified the relationship between the drainage data and the exposure level of the borehole and the layout of the borehole, compared the gas concentration in the upper corner of the working face before and after the drainage, and constructed a three-dimensional comprehensive drainage mode for the high-gassy working face, which provided a worth-promoting method that supports surrounding rock oil-type gas and gas treatment in the high-gas mining area.

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Evaluating the maximum rate of penetration for drilling borehole in soft coal seam

Cited by 8 publications

References 37 publications

Gas Migration around Large Diameter Borehole with the Protective Screen Pipe in Fractured Soft Coal Seam

Gas Migration around Large Diameter Borehole with the Protective Screen Pipe in Fractured Soft Coal Seam

Experimental Study on the Damage and Crack Evolution Characteristics of TS-RCR Structural Bodies under Cyclic Loading and Unloading

Study on Key Parameters of Directional Long Borehole Layout in High‐Gas Working Face

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