Evolution and application of in-seam drilling for gas drainage

Hungerford, Frank; Ren, Ting X; Aziz, Naj

doi:10.1016/j.ijmst.2013.07.013

Cited by 75 publications

(15 citation statements)

References 3 publications

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“…Coal industry serves an important role in the rapid growth of China's economy, and the increase in coal demand has brought an increase in the depth of mining. As a result, many disasters have occurred, causing a large number of casualties and property losses . Figure shows a statistical chart of the causes for different coal mine accidents (eg, blasting, gas, fire, floor, transportation, electromechanical, and other disasters) in China from 2007 to 2017.…”

Section: Introductionmentioning

confidence: 99%

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Wang

Chang

et al. 2019

Energy Science & Engineering

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The effective extraction radius of borehole is the main parameter for determining the design and layout for coalbed methane extraction. This paper is aimed at the problem that the criteria and calculation methods for the effective extraction radius of coal seams are not comprehensive. With Wudong Coal Mine in China taken as an example, the critical gas pressure (0.441 MPa) for the calculation of effective extraction radius is first defined. Next, the gas seepage unit model around the borehole is developed, and the theoretical mathematical expression to calculate the effective extraction radius is derived. Then, the numerical simulation of gas extraction is carried out through a computational fluid dynamics program, and the effective extraction radius is obtained numerically. Furthermore, the influence of original gas pressure, borehole diameter, and negative pressure of gas extraction on gas extraction is analyzed. Finally, the results from the theoretical calculation and numerical simulation are validated by the field engineering measurement and the average relative error is small (less than 10%). The results indicate that the effective extraction radius has a linear relationship with the extraction time. Moreover, it is found that the original gas pressure is the main factor affecting the effective extraction radius and the effective extraction radius is proportional to the borehole diameter and negative pressure through analysis. Therefore, the above findings can provide a theoretical basis for determining parameters such as borehole spacing and extraction time of gas extraction in coal mines.

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Section: Introductionmentioning

confidence: 99%

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Wang

Chang

et al. 2019

Energy Science & Engineering

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“…Due to the low working conditions in the underground test, the test efficiency was low. So that it was necessary to simulate the underground drilling environment as far as possible on the ground, and to test the function and performance of the electromagnetic wave drilling system prototype [8][9] . The difference between the groundless transmission test and the open-air ground transmission test was that whether the instrument was transmitted or not through the surrounding water.…”

Section: Prototype Testmentioning

confidence: 99%

Key Technologies and Applications of Gas Drainage in Underground Coal Mine

Zhang

Xue

Cheng

et al. 2018

IOP Conf. Ser.: Earth Environ. Sci.

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Exploration drilling for pre-mining gas drainage in coal mines E A Shubina, V I Brylin, V G Lukyanov et al. Abstract. It is the basis for the long-drilling directional drilling, precise control of the drilling trajectory and ensuring the effective extension of the drilling trajectory in the target layer. The technology can be used to complete the multi-branch hole construction and increase the effective extraction distance of the coal seam. The gas drainage and the bottom grouting reinforcement in the advanced area are realized, and the geological structure of the coal seam can be proved accurately. It is the main technical scheme for the efficient drainage of gas at home and abroad, and it is applied to the field of geological structure exploration and water exploration and other areas. At present, the data transmission method is relatively mature in the technology and application, including the mud pulse and the electromagnetic wave. Compared with the mud pulse transmission mode, the electromagnetic wave transmission mode has obvious potential in the data transmission rate and drilling fluid, and it is suitable for the coal mine. In this paper, the key technologies of the electromagnetic wave transmission mode are analyzed, including the attenuation characteristics of the electromagnetic transmission channel, the digital modulation scheme, the channel coding method and the weak signal processing technology. A coal mine under the electromagnetic wave drilling prototype is developed, and the ground transmission experiments and down hole transmission test are carried out. The main work includes the following aspects. First, the equivalent transmission line method is used to establish the electromagnetic transmission channel model of coal mine drilling while drilling, and the attenuation of the electromagnetic signal is measured when the electromagnetic channel measured. Second, the coal mine EM-MWD digital modulation method is developed. Third, the optimal linear block code which suitable for EM-MWD communication channel in coal mine is proposed. Fourth, the noise characteristics of well near horizontal directional drilling are analyzed, and the multi-stage filter method is proposed to suppress the natural potential and strong frequency interference signal. And the weak electromagnetic communication signal is extracted from the received signal. Finally, the detailed design of the electromagnetic wave while drilling is given.

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“…CMM pre‐drainage is generally believed to be one of the most effective methods to manage and eliminate outburst dangers . Cross‐measure boreholes and in‐seams boreholes are widely used for CMM pre‐drainage in China . Cross‐measure boreholes are drilled from roadways in the roof strata or the floor strata, and in‐seam boreholes are directly drilled in the coal seam.…”

Section: Introductionmentioning

confidence: 99%

An improved method for high‐efficiency coal mine methane drainage: Theoretical analysis and field verification

Liu

Zhang

Wang

et al. 2018

Energy Science & Engineering

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Degassing a coal seam with in‐seam boreholes is an important method for mitigating the gas hazards in the underground coal mine. However, the low strength of the outburst‐proven coal limits the borehole sealing performance and borehole space maintaining, and thus influences the drainage performance of in‐seam boreholes. This study was conducted to seek a method to improve the sealing performance and borehole space maintaining for high‐efficiency CMM drainage. A visco‐elastic plastic model involving the plastic softening and dilatancy features for soft coal was proposed, and the deformation, shrinkage, and fracture characteristics of the coal surrounded a borehole and a roadway were analyzed. An enormous amount of connective fractures generated in the failure zone and the plastic zone, and the plastic zone develops timely for the creep behavior of coal, which aggravates the difficulties of borehole sealing. A comprehensive approach including the theoretical method and the technical method was developed to determine the proper sealing depth which can significantly influence the sealing performance. The sieve tubes made of high‐density polyethylene has been used to maintain the borehole space during the scheduled pre‐drainage period. A series of field tests were conducted in an outburst‐proven coal seam to verify the feasibility of the comprehensive approach and the borehole space maintaining method. Field tests showed that the comprehensive approach to determine the proper sealing depth and the installing of sieve tubes to protect the borehole space can provide favorable conditions for maximum CMM pre‐drainage from outburst‐prone coal and maximum utilization of the in‐seam boreholes.

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Evolution and application of in-seam drilling for gas drainage

Cited by 75 publications

References 3 publications

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Key Technologies and Applications of Gas Drainage in Underground Coal Mine

An improved method for high‐efficiency coal mine methane drainage: Theoretical analysis and field verification

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