Anisotropy of crack initiation strength and damage strength of coal reservoirs

HAO Xianjie,WEI Yingnan,YANG Ke,SU Jian,SUN Yingfeng,ZHU Guangpei,WANG Shaohua,CHEN Haibo,SUN Zhuowen

Table 2 Crack initiation strengths and damage strengths of coal reservoir samples from different methods.

Sample No. Crack initiation strength/MPa Crack initiation ratio Damage strength/MPa Damage ratio Crack volume strain method AE method Crack volume strain method AE method Crack volume strain method AE method Crack volume strain method AE method AE count AE energy AE count AE energy AE count AE energy AE count AE energy Z1 8.1 14.96 14.96 0.17 0.320 3 0.320 3 44.7 41.44 41.17 0.96 0.887 3 0.881 6 Z2 8.4 18.14 16.07 0.21 0.449 0 0.397 8 23.7 30.61 22.84 0.59 0.757 8 0.565 5 Z3 10.2 11.88 11.14 0.23 0.268 8 0.252 1 42.4 36.84 39.27 0.96 0.833 8 0.888 8 Z4 8.7 20.35 22.55 0.18 0.419 8 0.465 3 47.6 42.83 45.05 0.98 0.883 6 0.929 5 Z5 9.9 14.21 13.92 0.27 0.389 0 0.381 1 27.8 28.33 24.94 0.76 0.775 8 0.683 0 Z6 10.4 10.98 17.06 0.21 0.221 3 0.343 8 43.3 36.35 37.15 0.87 0.732 5 0.748 6 F1 6.9 5.59 6.54 0.31 0.253 6 0.296 8 17.5 18.89 14.48 0.79 0.856 9 0.656 8 F2 4.7 10.51 8.33 0.21 0.465 0 0.368 3 17.2 15.83 16.36 0.76 0.700 3 0.723 4 F3 6.1 4.86 7.78 0.34 0.271 2 0.434 3 14.8 13.44 13.93 0.83 0.750 6 0.777 7 F4 4.8 10.60 6.78 0.20 0.448 1 0.286 7 7.8 21.62 22.07 0.33 0.913 7 0.933 0 F6 8.7 12.83 13.04 0.29 0.431 0 0.437 9 25.5 17.47 17.58 0.86 0.586 8 0.590 5 N1 8.6 11.15 11.17 0.35 0.459 7 0.460 7 19.3 18.23 18.49 0.80 0.751 6 0.762 6 N2 7.4 12.46 12.70 0.28 0.475 3 0.484 7 24.3 24.88 25.00 0.93 0.949 1 0.953 8 N3 5.7 7.64 8.92 0.25 0.353 9 0.413 0 19.7 18.92 19.19 0.91 0.876 5 0.888 9 N4 5.5 8.31 5.49 0.30 0.432 8 0.286 1 16.3 16.45 16.57 0.85 0.856 9 0.863 1