Gas desorption index of drill cuttings affected by magmatic sills for predicting outbursts in coal seams
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ORIGINAL PAPER
Gas desorption index of drill cuttings affected by magmatic sills for predicting outbursts in coal seams Long-biao Cheng 1 & Liang Wang 1,2,3 & Yuan-ping Cheng 2 & Kan Jin 1 & Wei Zhao 1 & Li-shuo Sun 1
Received: 15 December 2014 / Accepted: 10 September 2015 / Published online: 16 December 2015 # Saudi Society for Geosciences 2015
Abstract Magma intrusion events accelerate the thermal evolution of coal seams, which could change their adsorptiondesorption characteristics and increase the outburst risk. To study the effects on the coal seam desorption index of drill cuttings under the magmatic sill, we compared and analyzed multiple physical parameter variations and desorption characteristics of the no. 10 coal seam in the normal and thermal evolution zone in the Haizi and Yangliu mines under a thick sill. Lab simulation, theoretical analysis, and field validation were used for determination of the coal seam gas desorption index. The results indicated that the metamorphic grade of the no. 10 coal seam is increased under the sill, and the coal sample desorption rate and desorption quantity were enhanced by the sill’s heat effect, which could also make the coal seam gas desorption index of the drill cutting indexes Δh2 and K1 based on desorption characteristics increase, in addition to increasing the coal risk. The influence on gas desorption indexes Δh2 and K1 could be reflected by the value D which shows a proportional trend; the effect on the coal seam of the Haizi coal mine with a 120-m-thick sill is stronger than in the Yangliu mine with approximately 70 m. In addition, with the
* Liang Wang [email protected] * Yuan-ping Cheng [email protected] 1
Key Laboratory of Coal Methane and Fire Control, Ministry of Education, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China
2
National Engineering Research Center of Coal Gas Control, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China
3
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
increase in the thickness of the sill, the gas desorption index becomes larger; the Δh2 of the no. 10 coal seam could have higher reliability than K1 in the normal and thermal evolution area. And the linear relationship between Δh2 and K1 will not change under different situations. Keywords Magmatic sill . Physical parameters . Desorption characteristics . Gas desorption index of drill cuttings
Introduction The coal and gas outburst is a very complicated dynamic in coal mines, and the study of the mechanisms of coal and gas outbursts is at the qualitative comprehensive effects hypothesis stage (Yu 1979, 1992; Anderson 1995). In the process of gas prevention and control, the outburst risk prediction is one of the most important links. There are various indexes in China for gas outburst prediction (Cheng et al. 2010; State Administration of Coal Mine Safety 2009), among which gas pressure and gas content are considered as the regional outburst prediction indexes, w
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