Tests on Vitrinite Reflectance of Coal and Analysis of Tectonic Stress Field

Abstract

AbstractIn order to deduce the tectonic stress field in North Henan by coal vitrinite reflectance, based on the principle that the tectonic stress is the main controlling factor of the vitrinite reflectance anisotropy (VRA), we made tests of coal vitrinite reflectance under microscope for directional coal specimen collected from Jiaozuo, Anyang, Hebi mining field in Henan province, and gained vitrinite reflectance ellipsoids (VRI) made up of reflectance maximum value, reflectance intermediate value and reflectance minimum value through some calculations to the testing data. The results show that the coal specimens in studied area indicate indicatrix of optical biaxial crystal, they have been suffered from intense tectonic deformation and the vitrinite reflectance anisotropy (VRA) is induced by tectonic stress. The tectonic stress field of North Henan obtained from vitrinite reflectance ellipsoids (VRI) is accordant basically with the tectonic stress field acquired from other methods, such as drilling, joints statistics and Henan province regional tectonic stress field analysis, but there is small difference that the tectonic stress field shows a left ward deflexion in Anyang and Hebi. In short, the method deducing tectonic stress field by vitrinite reflectance anisotropy (VRA) is feasible and effective.