THE CHARACTERISTICS OF THE FRACTURE FILLINGS IN COAL RESERVOIRS AND ITS STUDY SIGNIFICANCE

The fracture fillings are mainly the products resulted by the interactions between the water solution in the fractures of surrounding rocks and the fluid in the coal resrvoirs,and the latter was generated by the pyrolysis of organic macerals and dominated by the gas phase.The location of interaction between both of them had a very important affect on the trap and preservative conditions of CBM pool.The trap condition of CBM pool was good and the gas saturation was high if the inorganic filling was developed only in the surrounding rock;otherwise,the trap condition of it was bad and the gas saturation was low if a great of inorganic filling had developed in the fractures of coal reservoirs.In addition,the inorganic filling had stopped up the fracdture passages in coal reservoirs and had reduced the permeability.