Research on high directional and long drilling technology for extracting pressure relief gas in slowly inclined coal bed

doi:10.16265/j.cnki.issn1003-3033.2024.S1.0024

Abstract

Abstract:

In order to investigate the spatio-temporal evolution of mining-induced fissures and change characteristics of pressure relief gas-enriched area in the overlying rock of the slowly inclined coal bed, physical similarity simulation and field monitoring method were used to analyze the evolution and distribution characteristics of the fissure in the overlying rock. The evolution characteristics of the pressure relief gas-enriched area were studied to determine the parameter arrangement scheme of the high directional drilling holes, and the effect test was carried out. The results show that the test working face has a height of 13 m along the caving zone of the coal bed, and the height of the fissure zone is 68.5 m. The fissure network along the working face is affected by the inclination angle of the coal bed, and the fracture angle of the working face is 54°-59°. The openness of the fissure development is gradually increasing upward from the working face, and the gas transportation channel is asymmetric. The whole life cycle of the gas extraction process by high directional drilling can be divided into the early stage of extraction, the middle stage of extraction, and the end stage of extraction according to the extraction volume fraction. In the early stage of extraction, the volume fraction is low. The middle stage of extraction has high efficiency in the whole life cycle of extraction. In the late stage of extraction, the volume fraction shows a sharp decline. After the implementation of the high directional and long drilling technology, the volume fractions of the gas in the upper corners of the working face and in the return-air tunnel are all less than 0.8%, indicating a good effect of the gas extraction, and the arrangement of the high drilling holes is reasonable.

Key words: slowly inclined coal bed, high directional and long drilling holes, gas extraction, pressure relief gas, mining-induced fissures

CLC Number:

X936

SHUANG Haiqing, LIU Zijia, LIN Haifei, ZHOU Bin, ZHANG Wenqi, LUO Yonggang. Research on high directional and long drilling technology for extracting pressure relief gas in slowly inclined coal bed[J]. China Safety Science Journal, 2024, 34(S1): 102-108.

Figures/Tables 11

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厚度/m	岩性	岩性描述
5.0	细砂岩	棕灰色,中部含少量方解石及菱铁矿,局部胶结有泥岩碎块
4.8	中粒砂岩	灰白色,中夹薄层砂质泥岩,含少重白云母及菱铁结核
1.4	细砂岩	惊黄色细砂岩,含自云母碎片
4.8	砂质泥岩	棕黄色及灰色砂质泥岩,下部0.9 m为浅灰色泥岩
1.9	砂质泥岩	黄灰色砂质泥岩中部含褐紫色菱铁矿结核
3.1	泥岩	浅灰色泥岩,含植物化石碎片,中部夹灰黄色砂质泥岩
1.9	砂质泥岩	深灰色、黑色砂质泥岩,含自云母碎片
2.1	细砂岩	灰黄色细砂岩,夹粉砂岩和白云母碎片
1.2	粗砂岩	灰色相砂岩,中部含少量泥质砂岩
1.8	粗砂岩	浅灰至灰白色粗砂岩,含白云母片
1.9	泥质砂岩	深灰色,下部为泥岩,局部夹薄层煤线
2.0	细砂岩	浅灰色细砂岩,中部含白云母
3.0	泥质砂岩	深灰色泥质砂岩
4.1	砂质泥岩	黑色砂质泥岩,平行层面含少里白云母碎片
3.5	己₁₅煤	黑色块状,光亮型煤

相似比	几何比 α_L	时间比 α_t	容重比 α_γ	应力比 α_σ	强度比 α_E
走向模型	100	10	1.5	150	150
倾向模型	200	14	1.5	300	300

钻孔编号	距顶板高度/m	距回风巷下帮/m	钻孔长度/ m	下筛管深度/m
1	18	25	522	489
2	21	30	525	510
3	24	35	525	327
4	27	38	522	457
5	30	43	513	501
6	36	48	501	501