水力压裂弱化顶板护孔技术

薛江达; 孙永康; 王军; 张庚

doi:10.13272/j.issn.1671-251x.2023080114

水力压裂弱化顶板护孔技术

doi: 10.13272/j.issn.1671-251x.2023080114

太原理工大学安全与应急管理工程学院，山西晋中　030600

基金项目: 国家自然科学基金资助项目（52004176）。

详细信息

作者简介:
薛江达（1998—），男，河南濮阳人，硕士研究生，主要研究方向为煤矿安全和瓦斯治理技术，E-mail：xuejiangda@126.com

通讯作者:
王军（1982—），男，山西和顺人，副研究员，硕士，主要研究方向为煤矿瓦斯及火防治理论与技术，E-mail：wangjun02182@163.com。

中图分类号: TD712.6
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出版历程
- 收稿日期: 2023-08-29
- 修回日期: 2024-03-26
- 网络出版日期: 2024-04-11

Hydraulic fracturing weakening roof borehole protection technology

School of Safety and Emergency Management Engineering, Taiyuan University of Technology, Jinzhong 030600, China

摘要

摘要: 煤矿工作面单翼布置顺序开采的情况下，工作面顺层钻孔容易受到邻近工作面采动支承应力影响导致钻孔失效。现阶段的护孔研究集中在增强钻孔本身强度，未针对影响钻孔稳定性的根本性因素提出解决措施。针对上述问题，提出了一种水力压裂弱化顶板护孔技术。通过水力压裂弱化顶板，减小作用在邻近工作面煤体上的采动支承应力峰值，阻断高支承应力向顺层钻孔周围煤体的传递，并在顺层钻孔内全程下筛管，保证煤体逸散出的瓦斯可以进入顺层钻孔。采用数值模拟分析了水力压裂弱化顶板前后顺层钻孔周围煤体垂直应力和塑性区变化规律，结果表明：通过水力压裂弱化顶板，顺层钻孔周围煤体的垂直应力峰值由21.2 MPa降低为9.1 MPa，煤体塑性区范围由19 m减小为11 m。根据数值模拟结果确定的水力压裂参数进行了现场测试，结果表明：采用水力压裂弱化顶板护孔技术后，钻孔瓦斯抽采体积分数平均值由3.6%提高到14.1%，瓦斯抽采混合流量平均值由1.28 m³/min降低为0.464 m³/min，未出现大范围顺层钻孔内发生煤体氧化而产生CO的情况。因此，水力压裂弱化顶板护孔技术可有效避免钻孔失效漏气，提高钻孔抽采效果，保证钻孔抽采安全。
- 水力压裂 /
- 弱化顶板 /
- 采动支承应力 /
- 顺层钻孔 /
- 塑性区
Abstract: In the case of sequential mining with single wing arrangement in coal mine working face, the drilling along the working face is easily affected by the support stress of adjacent working faces, leading to drilling failure. At present, research on borehole protection focuses on enhancing the strength of the borehole itself, without proposing solutions to the fundamental factors that affect borehole stability. In order to solve the above problems, a hydraulic fracturing weakening roof borehole protection technology has been proposed. By using hydraulic fracturing to weaken the roof, the peak mining support stress acting on adjacent coal working faces is reduced, and the transmission of high support stress to the surrounding coal bodies in the bedding boreholes is blocked. The entire process of screening is carried out in the bedding boreholes to ensure that the gas escaping from the coal body can enter the bedding boreholes. Numerical simulation is used to analyze the changes in vertical stress and plastic zone of the coal body around the borehole before and after hydraulic fracturing weakening the roof. The results show that by weakening the roof through hydraulic fracturing, the peak vertical stress of the coal body around the borehole decreases from 21.2 MPa to 9.1 MPa, and the plastic zone range of the coal body decreases from 19 m to 11 m. According to the numerical simulation results, hydraulic fracturing parameters are determined and tested on site. The results show that after using hydraulic fracturing weakening roof borehole protection technology, the average volume fraction of gas extraction from boreholes increases from 3.6% to 14.1%. The average mixed flow rate of gas extraction decreases from 1.28 m³/min to 0.464 m³/min. There is no occurrence of coal oxidation and CO production in a large area of bedding boreholes. Therefore, hydraulic fracturing weakening roof borehole protection technology can effectively avoid drilling failure and gas leakage, improve drilling and extraction efficiency, and ensure drilling and extraction safety.
- hydraulic fracturing /
- weakening roof /
- mining support stress /
- horizontal drilling /
- plastic zone

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图 1 工作面地质柱状图

Figure 1. Geological column histogram of the working face

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图 2 工作面布置

Figure 2. Layout of the working face

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图 3 钻孔围岩弹塑性区分布

1—破碎区；2—塑性区；3—弹性区；4—原岩应力区。

Figure 3. Distribution of borehole surrounding rock elastoplastic zones

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图 4 数值模型

Figure 4. Numerical model

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图 5 钻孔周围煤体应力分布云图

Figure 5. Cloud map of coal stress distribution around borehole

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图 6 水力压裂弱化顶板前煤体垂直应力演化规律

Figure 6. Evolution law of vertical stress of coal before hydraulic fracturing weakening roof

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图 7 水力压裂弱化顶板后煤体垂直应力演化规律

Figure 7. Evolution law of vertical stress of coal after hydraulic fracturing weakening roof

下载: 全尺寸图片幻灯片

图 8 水力压裂弱化顶板前后回采40 m时煤体塑性区分布

Figure 8. Plastic zone distribution of coal when mining 40 m before and after hydraulic fracturing weakening roof

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图 9 水力压裂弱化顶板施工

Figure 9. Construction of hydraulic fracturing weakening roof

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图 10 瓦斯抽采体积分数变化曲线

Figure 10. Variation curve of gas extraction volume fraction

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图 11 瓦斯抽采混合流量变化曲线

Figure 11. Variation curve of mixed flow rate of gas extraction

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图 12 CO体积分数变化曲线

Figure 12. Variation curve of CO volume fraction

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表 1 各岩层物理力学参数

Table 1. Physical and mechanical parameters of each rock formation

岩性	体积模量/GPa	剪切模量/GPa	黏聚力/MPa	内摩擦角/（°）	抗拉强度/MPa	密度/（kg·m⁻³）
铝质泥岩	10.0	5.00	2.50	40	2.0	2 530
15号煤	5.3	2.36	1.25	32	1.5	1 380
泥岩01	10.0	6.00	1.50	23	1.3	2 300
14号煤	5.3	2.36	1.25	32	1.5	1 380
泥岩02	10.0	6.00	1.50	23	1.3	2 300
K2石灰岩	14.0	9.00	3.00	40	2.0	2 800
细粒砂岩	15.0	9.20	2.70	32	2.5	2 700

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