A flexible gel sealing material and a novel active sealing method for coal-bed methane drainage boreholes

Xiang, Xianwei; Zhai, Cheng; Xu, Yanming; Yu, Xu; Xu, Jizhao

doi:10.1016/j.jngse.2015.08.016

Cited by 57 publications

(21 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As discussed above, 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. The visco‐elastic zone around the roadway is with low permeability, which acts as the natural barrier of air leakage . It is difficult for the outside air to leak into the borehole through the visco‐elastic zone.…”

Section: The Principle and A Comprehensive Approach To Determine A Prmentioning

confidence: 99%

“…The visco-elastic zone around the roadway is with low permeability, which acts as the natural barrier of air leakage. 30 It is difficult for the outside air to leak into the borehole through the visco-elastic zone. Therefore, it can be deduced that the sealing length of an in-seam CMM drainage borehole should be at least equal to or greater than the radius of the plastic zone.…”

Section: Basic Requirementsmentioning

confidence: 99%

See 1 more Smart Citation

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

Liu

Zhang

Wang

et al. 2018

Energy Science & Engineering

View full text Add to dashboard Cite

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.

show abstract

Section: The Principle and A Comprehensive Approach To Determine A Prmentioning

confidence: 99%

Section: Basic Requirementsmentioning

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

View full text Add to dashboard Cite

show abstract

“…To ensure the sealing effect, the sealing depth of the borehole should be more than that of the plastic zone (Xiang et al, 2015). However, it is not easy to determine the depth of the plastic zone in the field.…”

Section: The Experience Of Sealing Depthmentioning

confidence: 99%

Determination of sealing depth of in-seam boreholes for seam gas drainage based on drilling process of a drifter

Zhang

Sun

et al. 2016

Engineering Geology

View full text Add to dashboard Cite

“…To solve the problem of difficulty in sealing fractures in coal and rock masses around the borehole [16][17][18][19][20], a new grouting solidification method is proposed in this study to seal fractures in coal and rock masses around the boreholes using an expandable material with high water content (as shown in Figure 1). The expandable material with high water content used in this method is a novel material formed by adding expander to high water content material [21].…”

Section: Introductionmentioning

confidence: 99%

Sealing Behavior and Flow Mechanism of Expandable Material Slurry with High Water Content for Sealing Gas Drainage Boreholes

Lan

2018

Geofluids

View full text Add to dashboard Cite

Predrainage of coalbed gas by underground drilling is one of the main approaches for eliminating gas disasters in coal mines. Owing to the unsatisfactory sealing effect of conventional sealing materials, coalbed gas drainage boreholes face serious air leakage, resulting in a relatively low concentration of the drained gas. This study presents a new grouting solidification method for sealing boreholes using expandable materials with high water content. An experimental test method was used to study the groutability, compression resistance, and gas permeability of the expandable materials with high water content, as well as their binding properties with coal mass at different water-cement ratios. On this basis, the governing equation for slurry permeation considering the viscosity time-varying characteristics of the expandable material with high water content was established and numerically calculated. The slurry permeation patterns of the expandable material with high water content under different grouting pressures and water-cement ratios were obtained. The results show the following: (1) the expandable material with high water content was better than cement to bind with coal mass; (2) the slurry of expandable material with high water content, with a water-cement ratio above 6 : 1, is groutable, and as the water-cement ratio increases, the groutability and penetrability of the expandable material with high water content increase; (3) the optimal grouting pressure for expandable slurry with high water content is 2-3 MPa; and (4) the higher the water-cement ratio, the greater the permeation range of expandable slurry with high water content, but the increase in the permeation range is relatively small, and the optimal water-cement ratio for expandable slurry with high water content is 7 : 1. Therefore, featuring strong groutability, good sealability, high compressive strength, microexpansion, and tight binding with coal mass, expandable materials with high water content are ideal for sealing coalbed gas drainage boreholes because of their efficiency in sealing fractures in coal and rock masses around the borehole.

show abstract

A flexible gel sealing material and a novel active sealing method for coal-bed methane drainage boreholes

Cited by 57 publications

References 15 publications

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

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

Determination of sealing depth of in-seam boreholes for seam gas drainage based on drilling process of a drifter

Sealing Behavior and Flow Mechanism of Expandable Material Slurry with High Water Content for Sealing Gas Drainage Boreholes

Contact Info

Product

Resources

About