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碎软低渗煤层顶板水平井分段压裂裂缝扩展规律及控制机制

碎软低渗煤层顶板水平井分段压裂裂缝扩展规律及控制机制

Research on controlling mechanism of fracture propagation of multi-stage hydraulic fracturing horizontal well in roof of broken soft and low permeability coal seam

Research on controlling mechanism of fracture propagation of multi-stage hydraulic fracturing horizontal well in roof of broken soft and low permeability coal seam

doi:
10.11764/j.issn.1672-1926.2017.11.019
摘要:
碎软低渗煤层的煤层气地面抽采,多年来一直是制约我国煤层气产业化发展和煤矿瓦斯灾害防治工作的技术瓶颈,也是世界性技术难题.通过建立表征碎软低渗煤层顶板水平井分段煤层气抽采模式的地质—工程模型,采用数值模拟的方法,开展了顶板水平井压裂裂缝扩展规律的研究,揭示了碎软低渗煤层顶板水平井压裂裂缝垂向上不仅完全能穿层进入沟通煤层,而且由于裂缝在顶板岩层中的脆性主导性扩展造成“拉扯”作用带动煤层中的裂缝共同横向扩展,在碎软煤层中形成的裂缝比直接对碎软煤层压裂形成的裂缝要长的多,压裂增产效果更好.同时,现场工程试验也验证了煤层顶板水平井压裂对碎软煤层的增产改造效果.我国晚古生代煤田碎软低渗煤层分布广泛,高瓦斯突出矿井众多.该研究成果对于这类煤层的煤矿区煤层气地面抽采,尤其是突出煤层的掘进煤巷条带瓦斯地面快速预抽和区域瓦斯消突,瓦斯灾害防治,具有借鉴和指导作用,应用前景良好.
Abstract:
Coalbed methane drainage of broken soft and low permeability coal seam from ground surface has always been a technical bottleneck that prevents CBM industrialization and coal mine gas disaster prevention and control work for a long time.It is also a worldwide technical problem.Based on the establishment of coalbed methane mode of multi-stage hydraulic fracturing horizontal well in roof strata of broken soft and low permeability coal seam,applying numerical simulation method,the mechanism of fracture propagation of multi-stage hydraulic fracturing and horizontal wells in roof strata of broken soft and low permeability coal seam was studied.It is revealed that the hydraulic fractures not only can grow from the high stress value of roof strata towards and throughout lower stress value of broken soft and low permeability coal seam,and also the length of fractures formed in underlying broken soft and low permeability coal seam is longer than that of directly fractured in broken soft and low permeability coal seam due to fractures propagation in the direction of length in relatively friable roof strata producing tear effect on broken soft and low permeability coal seam at the same time of fractures propagation of the mode of multi-stage hydraulic fracturing horizontal well in roof strata of broken soft and low permeability coal seam.Fracturing effect of multi-stage hydraulic fracturing horizontal well in roof strata of broken soft and low permeability coal seam was verified in field.The distribution of broken soft and low permeability coal seams in Late Paleozoic in China is widely distributed,which are mostly high gas outburst coal mine.The research results of this paper can be used for the CBM drainage in this kind of coal seam,in particular,which can be used as a reference and guidance for the rapid coal gas pre-pumping in the heading of coal seam strip of outburst coal seams,regional gas outburst control and gas disaster prevention.The drainage model has a good prospect of application.
作者 巫修平 张群
Author: Wu Xiu-ping Zhang Qun
作者单位 中煤科工集团西安研究院有限公司,陕西西安,710054
期 刊: 天然气地球科学 ISTIC EI SCI PKU CSSCI
Journal: Natural Gas Geoscience
年,卷(期) 2018, 29(2)
分类号 TE132.2
关键词: 碎软低渗煤层 知识脉络 顶板岩层 知识脉络 水平井 知识脉络 分段压裂 知识脉络 裂缝扩展 知识脉络
Keywords: Broken soft and low permeable coal seam Roof strata Horizontal well Multi-stage hydraulic fracturing Fracture propagation
机标分类号
基金项目 “十三五”国家科技重大专项项目,中煤科工集团西安研究院有限公司科技创新基金项目
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