A Mechanical Model of Gas Drainage Borehole Clogging under Confining Pressure and Its Application

Wang, Yonglong; Yu, Zaijiang; Wang, Zhenfeng

doi:10.3390/en11102817

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Comparing the test results of different punching sequences, the top-to-bottom punching sequence has a higher frequency of blockage and is more likely to result in dropped boreholes and blowouts. The reasons for this phenomenon are as follows: on the one hand, when punching from the top of the coal seam to the bottom of the coal seam, the length of the slag removal section is longer [23]. On the other hand, the coal body around the borehole wall is deformed with new fissures during the drilling process, and 9 Geofluids its strength is reduced under the softening effect of the returned slag water, resulting in the failure of the broken slag to be discharged from the borehole in time and the occurrence of blockage.…”

Section: Relationship Between Punching Sequence and Boreholementioning

confidence: 99%

Research on Optimization of Large Flow Hydraulic Punching Process in Zhaozhuang Mine

Zhang

2022

Geofluids

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Taking hydraulic punching test of Zhaozhuang Mine as engineering background, by comparing the field application effects of different hydraulic punching processes, the relationship between coal moisture content around the borehole blockage and gas extraction effect was monitored and analyzed. The following conclusions were drawn: the occurrence of borehole blockage was the result of the comprehensive action of coal slag particle size and slag discharge capacity of punching return water. Blocking the borehole led to the accumulation of a large amount of punching high-pressure water and coal slag in the borehole, which compressed and infiltrated the surrounding coal body and reduced gas extraction efficiency of borehole. Under the condition of the same amount of coal produced by punching, the different punching methods led to the great difference in the influence radius of punching. The large flow three-stage coal-breaking hydraulic punching system developed according to the borehole blockage mechanism can effectively reduce the particle size of coal slag, increase the punching flow, effectively avoid borehole blockage, and improve gas extraction efficiency of borehole.

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Section: Relationship Between Punching Sequence and Boreholementioning

confidence: 99%

Research on Optimization of Large Flow Hydraulic Punching Process in Zhaozhuang Mine

Zhang

2022

Geofluids

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“…Engineering rock mass reinforcement has always been a hot issue of widespread concern 1,2 . Fully grouted bolts, as an economical and effective rock mass reinforcement technique, have been widely used in mining, civil engineering and water conservancy projects 3,4 .…”

Section: Introductionmentioning

confidence: 99%

Investigation on the pullout bearing properties and stress characteristics of fully grouted bolts in layered rock mass

Du,

Zhang,

Feng

et al. 2024

Energy Science & Engineering

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Coal‐measure strata is a typical layered structure, a better understanding of the bearing characteristics of fully grouted bolts in layered rock mass is of great significance for roadway support. However, limited studies have been conducted to investigate the bearing performance of fully grouted bolts in layered rock mass. In this paper, a numerical model of fully grouted bolt in layered rock mass was established, and a tri‐linear bond–slip model of the anchorage interface was imported into the numerical model by the user‐defined Fish language. The effects of strata sequence, strata thickness, and strata number in layered rock mass on the bearing performance of fully grouted bolts were systematically analyzed. The results show that fully grouted bolts in soft–hard type (SH‐type) layered rock mass has higher bearing capacity. The greater the thickness of the soft rock in the layered rock mass, the more significant the influence of the strata sequence on the bearing performance of fully grouted bolts. The bearing capacity of fully grouted bolts decreases with the increase of the thickness ratio of soft rock to hard rock. The greater the thickness of the hard rock in the layered rock mass, the more beneficial to the bearing performance of fully grouted bolts. With the increase of the strata number, the bearing capacity of fully grouted bolts gradually decreases. For bolt support of layered rock mass, the deep anchoring foundation of fully grouted bolts should be arranged in hard rock or elastic zone rock as much as possible, and rock grouting can be adopted to reduce the difference in mechanical properties between layered rock mass and improve the durability of fully grouted bolts. The research results may provide useful guidance and reference for the support design of fully grouted bolts.

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“…For coal seams with high strength and low gas content, it is feasible to conduct borehole drilling in the coal seam by conventional drilling techniques. However, there are many soft and outburst-prone coal seams in the provinces of Henan, Anhui, Guizhou, Shanxi, etc., in China, where the borehole length in the coal seam is very short and cannot meet the requirement of coal seam gas efficient extraction [8][9][10]. Therefore, it is urgent to develop novel drill pipes to improve the borehole length in soft and outburst-prone coal seams and clarify their drilling cutting discharge mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…[32]. Under high in situ stress, borehole deformation is inevitable, which causes an increase in compressive force imposed on the surface of the drill pipes, locking the drill pipe [10]. Therefore, drilling cutting transportation between the borehole wall and drill pipes is unreliable for long-distance borehole drilling in soft and gas outburst-prone coal seams.…”

Section: Introductionmentioning

confidence: 99%

Parameter Optimization of Drilling Cuttings Entering into Sieve Holes on a Surface Multi-Hole (SMH) Drill Pipe

et al. 2022

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The borehole drilling distance is short in soft and gas outburst-prone coal seams because of drill pipe jamming induced by cuttings accumulating in the borehole, hindering coal mine gas hazard prevention and utilization. A surface multi-hole (SMH) drill pipe composed of a bearing layer, fluid layer, and anti-sparking layer was proposed preliminarily, where several sieve holes were also set. To study the process of drilling cuttings in boreholes entering into the inner hole of an SMH drill pipe and its influencing factors, mechanical model analysis, CFD-DEM simulation, and a physical experiment were conducted. Our research results show the cutting entering region (CER) of the SMH drill pipe shrinks with the rotary speed, expands with the external extrusion force, and is offset with the sieve hole inclination angle. The drilling cuttings migrate and accumulate over time between the borehole wall and SMH drill pipe, which increases their compressive forces and induces increases in the mass and diameter of those entering into the sieve holes. The sieve hole diameter and depth are critical factors impacting the drilling cuttings entering into the sieve holes, which is also related to an appropriate rotary speed of the drill pipe. Finally, SMH drill pipes with a sieve hole diameter of 10 mm, inclination angle of 10°, and depth of 8 mm were determined and trial-manufactured.

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A Mechanical Model of Gas Drainage Borehole Clogging under Confining Pressure and Its Application

Cited by 8 publications

References 13 publications

Research on Optimization of Large Flow Hydraulic Punching Process in Zhaozhuang Mine

Research on Optimization of Large Flow Hydraulic Punching Process in Zhaozhuang Mine

Investigation on the pullout bearing properties and stress characteristics of fully grouted bolts in layered rock mass

Parameter Optimization of Drilling Cuttings Entering into Sieve Holes on a Surface Multi-Hole (SMH) Drill Pipe

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