Optimum technology of horizontal well drilling layer in coal reservoir

In order to optimize the layer selection of coal horizontal well drilling and achieve the best fracturing effect, through tensile strength test, triaxial compres sive strength test and the determination of coal sample determine the mechanical parameters, and using Moore-Coulomb criterion calculate coal roof and floor mud win dow, the stability of the wellbore is analyzed by the method mentioned above. The basic method of grey theory is applied to quantitatively analyze the factors affecting t he layer selection and fracturing effect, and determine the primary and secondary relation of the factors, creating a gray GM( 1, N) model to achieve the reference num ber of Columns of ash equations and differential equations, and then evaluation of the fracture and compression capacity forecast. The results showed that the mechani cal properties of the roof and floor was stable, the drilling fluid density window was 1. 09 ~ 5. 61 g/cm3, and the adjustment range was wider, well drilling in the roof and floor was stable. Overall error and the maximum error of model did not both exceed 10%, the model predicts that the output of coal bed methane was in agreement with the actual production data, and there was clear upward trend.