Sensitivity analysis on borehole effective extraction radius variation based on multiple linear regression model

To investigate effects of multiple factors on effective extraction radius of gas drainage borehole, a mathematical gas-solid coupling model is developed. Impacts of original gas pressure, borehole diameter, extraction time and initial coal permeability on effective extraction radius are qualitatively studied by adopting Comsol Multiphysics analysis. Furthermore, with the effective extraction radius as index, orthogonal experimental design analysis on multiple factors’ effects is conducted. Quantitative multiple linear regression model between effective extraction radius and each influencing factor is established by using SPSS method, with fitted correlation coefficient being 0.858. Extreme difference analysis and multiple regression analysis show that the significance of factors’ effects on effective extraction radius could be ranked as (from largest to smallest): initial coal permeability, original gas pressure, borehole diameter. There is no multicollinearity. Meanwhile, the distribution of residuals is normal, indicating that the constructed multiple linear regression model has good validity and reliability, which could provide references for gas extraction borehole design and real-time optimization of gas extraction parameters.