Characteristics of Emphasis Type="Italic"P/Emph

Authors: Xiaodong Zhang Pengpeng Li Yanhui Yang Zhigang Du

Publish Date: 2017/02/15

Volume: 10, Issue: 4, Pages: 75-

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Abstract

The degree of deformation of coal under the action of geological structure has important effects on the permeability and gasbearing properties of a coal reservoir Therefore it is critical to understand how the characteristics of coals vary with degree of deformation in coalbed methane CBM exploration and exploitation In this work Young’s modulus and Poisson’s ratio of coal samples with various degrees of deformation cored from the CBM wells in South Qinshui Basin China were tested with an electrohydraulic servocontrolled rock mechanic testing system RMT 150B Statistical analysis was subsequently conducted with the corresponding Pwave times The results demonstrate that the destructive effect of geological structure had significant influences on the Young’s modulus of coals Poisson’s ratio had no significant correlation but Young’s modulus decreased with increased deformation and coals can thus be classified into one of three types based on the critical values of Young’s modulus Further study found that Pwave time had a positive linear correlation with Swave time in coal samples and Pwave time is obviously shorter than Swave time with the same coal Both Pwave and Swave times become longer with increased deformation Pwave time is also linearly correlated with Young’s modulus Based on well log data values inferred from the statistical formulas among Pwave time Swave time and Young’s modulus can provide a more accurate classification in terms of the degree of coal deformationThis work was supported by the National Natural Science Foundation NNSF Grant No 41372162 provided by National Natural Science Foundation of China and University Innovative Research Team in Science and Technology Program 14IRTSTHN002 funded by Henan Province

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