Experimental study on mechanical properties of coal rocks in re-fracturing

Abstract

Taking high rank coal in Qinshui Basin as the research object, the mechanical parameters of the coal rocks after primary fracturing with quartz sand filling the fracture are measured, and the variation law of the mechanical properties of the coal rocks after sand filling is analyzed to provide reliable technological parameters for multiple fracturing. The results show that Poisson's ratio is 22.6% higher than the initial average, Young's modulus is 47% lower than the initial average, and permeability of low-permeability coal seam is nearly 10 times higher. The results indicates that in the development of high rank coalbed methane, the change of mechanical properties caused by quartz sand filling after the first fracturing of coal rocks can provide relatively real basic data for the design of the second fracturing process and improve the reliability of the design.

Keywords

• Coal rocks fracture
• Repeated fracturing
• Mechanical properties
• Experiment