摘要
为了研究水力冲孔卸压增透机理,以有效解决单一松软低渗煤层抽采困难的问题,利用自主研发的水力冲孔物理模拟试验系统,开展了不同转速条件下的水力冲孔试验,并对比冲孔前后煤层瓦斯抽采过程中瓦斯压力演化规律,分析冲孔作用对煤层瓦斯抽采达标范围的影响。研究结果表明:随冲孔转速提高,冲孔出煤量、冲孔孔洞等效半径及冲孔卸压半径增大,导致相同抽采时间条件下抽采达标范围增大;冲孔卸压半径在地应力较大的方向较大,在地应力较小的方向较小,冲孔卸压半径为冲孔孔洞等效半径的1.6~2.0倍;在冲孔卸压半径以内,抽采初期瓦斯压力下降速率明显提高,在冲孔卸压半径以外,抽采初期瓦斯压力下降速率影响不明显,抽采一段时间后,瓦斯压力下降速率明显提高;瓦斯抽采达标区域形状与冲孔卸压范围形状相似,在垂直于钻孔截面上近似为椭圆。
Ln order to study the pressure released and permeability improved mechanism of the hydraulic borehole flushing and effectively solve a gas drainage problem in a single soft and low permeability seam,a self researched and developed physical simulation experiment system of the hydraulic borehole flushing was applied to conduct the experiment of the hydraulic borehole flushing under the condition of the different rotary speed. A gas pressure evolution law during the seam gas drainage process before and after the hydraulic borehole flushing was compared and an analysis was conducted on the hydraulic borehole flushing function affected to the target scope of the seam gas drainage. The study results showed that with the flushing rotary speed increased,the flushed coal quantity from the borehole,an equivalent radius of the flushed borehole and the pressure released radius of the flushed borehole were increased and thus the gas drainage target scope was increased under the same time condition of the gas drainage. The pressure released radius of the flushed borehole would be high in a high direction of the geostress and would be low in a low direction of the geostress. The pressure released radius of the flushed borehole was 1.6 ~ 2.0 times larger than the equivalent radius of the flushed borehole. Within the pressure released radius of the flushed borehole,during the initial period of the gas drainage,the gas pressure decreased speed rate was obviously increased. Beyond the pressure released radius of the flushed borehole,during the initial period of the gas drainage,the gas pressure decreased speed rate was not obvious.After a time period of the gas drainage operation,the gas pressure decreased speed rate was obviously increased. The form of the gas drainage target region was similar to the form of the flushed borehole pressure released scope and would similarly be an ellipse on the cross section of the vertical borehole.
出处
《煤炭科学技术》
CAS
北大核心
2017年第6期55-60,共6页
Coal Science and Technology
基金
国家科技重大专项资助项目(2016ZX05044)
河南省创新型科技人才队伍建设工程资助项目(164100510024)
国家自然科学基金重点资助项目(51434003)
关键词
水力冲孔
卸压增透
钻孔
瓦斯抽采
hydraulic borehole flushing
pressure released and permeability improved
drill boreholes
gas drainage
