GSI-JP crushed classification prediction methodof coal rock based on logging information

By means of the logging data and Hoek-Brown criterion, formula of geological strength index (GSI) and jointing parameter (JP) of rock strength index (RMi) are derived, and a GSI-JP correction analysis method of coal crushed classification at wellbore direction is given. Considering hierarchical stress model, coal principal stresses are analyzed, consequently coal crushed classification auxiliary criterion is presented based on the Hoek-Brown criterion. According to the magnitude of GSI-JP and coal crushed coefficient, four grades of A, B, C, and D are divided for coal crushed degree, and coal crushed classification standard is determined. Using the classification method and standard, the distribution regularity of coal crushed degree is studied for ZP-1 Well in Qinshui basin. The research results show that coal correction GSI value of ZP-1 Well is 30～50, JP value of RMI is 0.1～0.25, and coal crushed coefficient is among 0.8～1.0. Thus, the coal crushed degree of ZP-1 is considered as grade B. The prediction results agree well with the experimental values obtained by electron microscope, therefore the classification method and standard are proved. Depending on the research results, the relevant computer program is developed.