Quantitative analysis on tectonically deformed coal and its physical properties in Shizhuang area of Qinshui Basin

Due to its unstable coal structure and low permeability,the tectonically deformed coal affects the develop- ment of coalbed methane. The quantitative analysis based on logging data is in favor of coal structure identification and then has an effective prevention for the adverse effects caused by the tectonically deformed coals. With the characteris- tics of the geophysical response of coals and the geological logging data,the tectonically deformed coal is identified. According to the characteristics of coal in Shizhuang area,this paper firstly discusses on the correlation between log- ging response parameters and coal structure. The results of principal component analysis show that the logging response characteristics of tectonically deformed coal in Shizhuang area have a high correlation with four loggings including son- ic,compensated neutron,density and caliper and the value of correlation is above 0. 8. In comparison,the correlation between resistivity logging parameter and structural coal is weak. Based on the response characteristics of four logging curves and combined with logging basic values of coal skeleton,it presents the coal structure index e as the identification index of tectonically deformed coal. When the value of e is above 1. 8,the tectonically deformed coals are generally developed. The comparison study of different coal structures shows that the tectonically deformed coal in the study area has the characteristics of low gas content,high evolution degree and high clay mineral content.