低渗透性煤体煤层气开采工艺及研究进展

Exploitation technology and research progress of coal-bed methane with low permeability coal seam

针对我国煤基质存在低渗透率、低饱和性、低储层压力和高含气量的特点,为了提升煤层气的开采率,分析了降压以及升温解吸技术、CO2驱替煤层CH4技术、混合气体驱替煤层气技术等煤层气解吸技术以及水力喷射压裂技术、三维高压旋转水射流扩孔煤层增透技术、循环冻融增透技术、高压空气爆破致裂煤层增透技术等煤层渗流通道增透技术的机理及技术的适用性,在此基础上提出了高压电脉冲水压压裂煤体技术,试验结果表明:高压电脉冲水压技术能够在钻孔周围产生丰富的长短不一、宽度不等、形态各异的微观和宏观裂纹,高压电脉冲水压对煤样能够产生非常好的致裂效果.

In connection with the characteristics of low permeability,low saturation,low reservoir pressure and high gas content in China＇s coal matrix,and in order to improve the exploitation rate of coal-bed methane,this paper analyzed the technology of pressure reduction and desorption by raising temperature,the technology of displacement of coal-bed methane by carbon dioxide,and the technology of displacement of coal-bed methane of coal-bed methane by mixed gas. At the same time,hydraulic fracturing technology,threedimensional high pressure rotary water jet reaming coal bed permeability enhancement technology,freezing and thawing cycle permeability enhancement technology,coal seam permeability improvement by high pressure air blasting and so on were analyzed. ？ Based on the mechanism and applicability of permeability augmentation technology in coal seam,a high-voltage electric pulsed hydraulic fracturing technology was proposed. The experimental results show that high-voltage electric pulsed hydraulic fracturing technology can produce not only the microscopic and macroscopic cracks of different widths and shapes around the borehole,but also the great cracking effects on coal samples.