水力压裂有效压裂半径的影响因素研究*

为改善水力压裂增透效果，提高煤层瓦斯抽采效率，减少矿井瓦斯灾害，明确不同因素对水力压裂有效压裂半径的影响，基于Mohr-Coulomb准则建立水力压裂渗流—损伤耦合方程，并且求得水力压裂破裂区半径运算公式；运用ABAQUS软件模拟并分析地应力σ、注水水压P、压裂孔径d及弹性模量E对水力压裂有效压裂半径L的影响；并通过灰色关联分析方法确定水力压裂有效压裂半径的主控因素。研究结果表明:水力压裂有效压裂半径与注水水压、压裂孔径及弹性模量呈递增关系，与煤层地应力呈递减关系；水力压裂有效压裂半径受煤层地应力的影响最大，注水水压次之，受压裂孔径和弹性模量的影响相对较弱。

Study on influencing factors of effective fracturing radius of hydraulic fracturing

In order to improve the effect of hydraulic fracturing permeation,improve the efficiency of coal seam gas extraction,reduce the mine gas disaster,and clarify the influence of different factors on the effective fracturing radius of hydraulic fracturing,the coupling equation of hydraulic fracturing seepage and damage was established based on the Mohr-Coulomb criterion,and the formula for calculating the radius of hydraulic fracturing rupture area was obtained.The influence of in-situ stress σ,water injection pressure P,fracturing aperture d and modulus of elasticity E on the effective fracturing radius L of hydraulic fracturing was simulated and analyzed by using ABAQUS software,and the main control factors of the effective fracturing radius of hydraulic fracturing were determined by the grey correlation analysis.The results showed that the effective fracturing radius of hydraulic fracturing was increasingly related to the water injection pressure,fracturing aperture and modulus of elasticity,and decreasingly related to the in-situstress of coal seam.The effective fracturing radius of hydraulic fracturing was most affected by the in-situ stress of coal seam,followed by the water injection pressure,and the influence of fracturing aperture and modulus of elasticity was relatively weaker.