Dissolution characteristics of gas in mine water and its application on gas pressure measurement of water-intrusion coal seam

In order to determine the gas pressure for water-intrusion borehole, this work proposed a new method for measuring gas pressure based on gas solubility. A series of laboratory experiments and field test were carried out to investigate the composition of mine water, the gas solubility in mine water and the gas dissolved amount in borehole water over time. Then, a new method and equipment were proposed to test the gas pressure for water-intrusion borehole in Taoyuan (TY) coal mine and Xinhu (XH) coal mine. Results showed that, the cations of mine water are dominated by K+ and Na+, and the anions are controlled by Cl and HCO3-. In addition, there are a certain amount of soluble organic matter in mines water. Then, the gas solubility increases with the rising equilibrium pressure while decreases with the growing temperature and salinity. It is noticed that the solubility of gas in mine aqueous solution is significantly higher than that in distilled water, which is mainly affected by the solubilization of soluble organic matter. Furthermore, the influence mechanism of various factors on the gas solubility was revealed based on the gap filling theory, hydration theory and organic matter solubilization effect. Finally, a self-developed equipment was used to test the amount of gas dissolved in the water-intrusion borehole, and the coal seam gas pressure was calculated and verified. The research results provide a new idea, equipment and method for the measurement of gas pressure in water-intrusion coal seam.

Automated summary

This study proposed a new method for measuring gas pressure based on gas solubility in order to determine the gas pressure for water-intrusion boreholes. Through laboratory experiments and field tests, the composition of mine water, gas solubility in mine water, and gas dissolved amount in borehole water over time were investigated, leading to the proposal of a new method and equipment for testing gas pressure in coal mines. The research results provide new insights for measuring gas pressure in water-intrusion coal seam.