Quantitative identification of deformed coals by geophysical logging

In order to quantitatively identify and obtain high-precision thickness,geophysical characteristics of deformed coal were studied with rock physics theory and logging applied technology.The results show that,compared with undeformed coal,deformed coal has low resistivity,high interval transit time,low bulk density,expanding well diameter,probability increasing neutron porosity in the geophysical logging curve.Based on the rock physics results,the porous structure exponent m was proposed as the quantitative identification index of deformed coal,and illustrated how to calculate with logging curves by Archie's formula and the method's feasibility.After the method was used to identify the deformed coal based on the practical logging data from two coalfield,the application results show that it is effective to use the porous structure exponent to identify the deformed coal and determine its thickness,and the method can greatly reduce the error of the qualitative identification.