Water-conserving mining influencing factors identification and weight determination in northwest China

Li-min, Fan; Ma, Liqiang; Yu, Yihe; Wang, Shuokang; Xu, Yujun

doi:10.1007/s40789-018-0233-2

Cited by 38 publications

(23 citation statements)

References 4 publications

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“…Undersaturated coal reservoirs may produce water mainly for a substantial period of time until desorption pressure is reached (Lyubarskii and Ivanov 1989;Boltenko 2013;Smith et al 2019). And then the coal reservoirs produce water mostly and little CBM and exhibit single-phase water flowing performances (Vicki and Paul 2002;Clarkson et al 2007;Liu et al 2017;Fan et al 2019). Therefore, the bottom-hole pressures are affected by well-head pressure, pressure drops of CBM column and water column in producing wellbores for single-phase water flow.…”

Section: Flowing Pressures In Single-phase Cbm Wellboresmentioning

confidence: 99%

Dynamic behavior of coalbed methane flow along the annulus of single-phase production

Liu

Liu³

2019

Int J Coal Sci Technol

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Dynamic behavior of coalbed methane (CBM) flow will provide the theoretical basis to optimize production performance for a given well. A mathematical model is developed to simulate flowing pressures and pressure drops of CBM column from well head to bottom hole. The measured parameters and independent variables of flow rates, flowing pressures and temperatures are involved in CBM producing process along the annulus. The developed relationships are validated against full-scale measured data in single-phase CBM wellbores. The proposed methodology can analyze the dynamic behavior in CBM reservoir and process of CBM flow with an overall accuracy of 2%. The calculating process of flowing pressures involves friction factor with variable Reynolds number and CBM temperature and compressibility factor with gravitational gradients. The results showed that the effect of flowing pressure on CBM column was more obvious than that on CBM and water column accompanied by an increase of dynamic water level. The ratios of flowing pressure on increment of CBM column to the whole column increased with the declined flow rates of water column. Bottom-hole pressure declined with the decreased flowing pressure of CBM column along the annulus. It will lead to the results of the increased pressure drop of CBM column and CBM flow rate in single-phase CBM wellbores.

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Section: Flowing Pressures In Single-phase Cbm Wellboresmentioning

confidence: 99%

Dynamic behavior of coalbed methane flow along the annulus of single-phase production

Liu

Liu³

2019

Int J Coal Sci Technol

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“…In view of the early warning and prevention of floor water inrush from mining above confined aquifer, accurate calculation of floor failure depth is the key, and accurate description of the stress distribution caused by mining is a prerequisite [29,30]. Based on the stress distribution of 41503 working face in Shandong Huatai Coal Mine, China, this study established a mechanical model in the semiinfinite body with the distributed load on the upper boundary (induced by mining) and the uniformly distributed load on the lower boundary (induced by confined aquifer) to calculate the stress in any point in the floor.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Analysis of the Failure Characteristics of Stope Floor Induced by Mining and Confined Aquifer

Lü

Wen-jun

Yin

et al. 2021

Shock and Vibration

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Mining above confined aquifer has become an important task for water inrush prevention in China. To study the failure characteristics of stope floor along the strike, a mechanical model under combined action of mining and confined aquifer was constructed, and the distribution of vertical stress, horizontal stress, and shear stress was obtained. Based on the Mohr–Coulomb criterion, the failure range of the floor is determined and verified by the in situ test. The results indicate the following. (1) Both vertical stress and horizontal stress in the stope floor take the junction of stress increasing area and stress decreasing area as the dividing line, forming two groups of “convex arches” at the solid coal side and the goaf side, respectively. (2) The vertical stress gradient in the solid coal side is significantly higher than that in the goaf side, while the horizontal stress gradient in the solid coal side is similar to that in the goaf side. The shear stress distribution is divided into three regions by the boundary between positive and negative shear stress, which makes the stope floor in this area to show compression shear or tension shear failure. (3) According to the in situ test, the maximum floor failure depth of 41503 working face is 11.38 m, which is quite close to the theoretical calculation result of 9.68 m. (4) Applying the mechanical model to five other coal mines with different mining conditions and stress states, the maximum absolute error between the measured and theoretical values of floor failure depth is 1.1 m, the average absolute error is 0.8 m, the maximum relative error is 8.2%, and the average relative error is 6.5%. The study provides a certain mechanical basis and reference for the floor failure mechanism induced by mining and confined aquifer.

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“…The west of China is abundant in coal resources, with a weak ecological environment. Protecting water resources is particularly important as water is the material basis for supporting regional ecological environment and economic and social development (Wang et al 2010;Fan et al 2019). However, in recent years, massive exploitation of coal has brought in serious environment problems to the area, such as ground surface damages caused by mine subsidence (Chang et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…During the past three decades, a plenty of field investigations, theoretical research, and engineering practices on water conservation mining have been implemented and documented. The water-retaining coal mining technology is aiming at protecting ecosystems (Fan 2017), which researches geological conditions identification (Li et al 2019a, b), aquifer stability control (Li et al 2018;Fan et al 2019), and water and ecological constraints (Cheng et al 2010;Ma et al 2019). Based on the theory of waterretaining coal mining, a groundwater monitoring network has been established for large-scale coal production bases in the northwest of China and a geological environment carrying capacity research system has been built (Sun et al 2019a;Fan et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Impact of coal mining on groundwater of Luohe Formation in Binchang mining area

Sun

Li-min²,

Xia

et al. 2020

Int J Coal Sci Technol

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Groundwater of Luohe Formation is the main water source for industrial and agricultural and residential use in Binchang mining area, which is one of the key elements to water conservation coal mining. However, few studies are available to document the enrichment characteristics and influence of underground coal mining on groundwater for the Luohe Formation. This study evaluates the changes of groundwater levels and spring flow caused by mining activities to explore the influence mechanism of coal mining on groundwater by comparatively analysing existing mining data and survey data combined with a series of mapping methods. The results show that the aquifer of Luohe Formation are gradually thinning south-eastwards, disappeared at the mining boundary. In the vertical direction, the lithological structure is distinct, due to alternative sedimentation of meandering river facies and braided river facies. According to the yielding property, the aquifer is divided into three sections, namely, strong water-rich section, medium water-rich section, and weak water-rich section, which are located in northwest and central part, southwest, and the rest part of the mining area, respectively. Mining of Tingnan Coal Mine since 2004 has caused a 3.16 to 194.87 meters drop in groundwater level of Luohe Formation. Until 2015, 70.10% of the mining area undergoes a groundwater level drop larger than 10.00 meters. Another influence of underground mining is that the total flow from 34 springs in 8 southern coal mines of the area has decreased by 286.48 L/s with a rate of decrease at 46.95% from 2007 to 2017. The areas that groundwater level falls or spring flow declines are manly located in the mine gob areas. Results also indicate that the ratio of the height of water conducted fracture zone to the mining height in Binchang mining area is between 16.85 and 27.92. This may increase ground water flow in vertical direction, causing a water level in the aquifer system to drop and ultimately decreasing the flow from the springs. The research results will provide data and theoretical support for the protection of groundwater resources and water conservation coal mining of Luohe Formation in Binchang mining area.

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Water-conserving mining influencing factors identification and weight determination in northwest China

Cited by 38 publications

References 4 publications

Dynamic behavior of coalbed methane flow along the annulus of single-phase production

Dynamic behavior of coalbed methane flow along the annulus of single-phase production

Mechanical Analysis of the Failure Characteristics of Stope Floor Induced by Mining and Confined Aquifer

Impact of coal mining on groundwater of Luohe Formation in Binchang mining area

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