A method for measuring gas pressure in water-invasion drilling based on vacuum conditions

Abstract

The invention discloses a method for measuring the gas pressure of a water invasion borehole based on vacuum condition. A measuring device used comprises a joint, a valve I, a valve II, a vacuum pump,a pressure gauge, a piston type volume measuring instrument and an ultrasonic degassing device. A valve III is arranged at the inlet end of the piston type volume measuring instrument. An inlet end of the pressure gauge is separately connected to one end of the joint and the vacuum pump through a rubber hose. The valve I is mounted on the rubber hose, connected to the joint, of the pressure gauge, and the valve II is installed on the rubber hose, connected to the vacuum pump, of the pressure gauge; and the outlet end of the pressure gauge is connected to the valve III through a rubber hose. Methane which is difficult to resolve under normal pressure can be quickly and effectively resolved out of borehole water when the vacuum negative pressure condition and ultrasonic degassing are combined, therefore the resolved amount of the methane in the borehole water is accurately obtained, and finally the gas pressure value of a mining coal seam is accurately obtained; and in addition, the method for measuring the gas pressure of the water invasion borehole based on the vacuum condition has the advantages of being stable, fast, effective, and environmentally friendly.

Description

technical field [0001] The invention relates to a method for measuring gas pressure in water-invasion drilling based on vacuum conditions. Background technique [0002] Measuring coal seam gas pressure is one of the important contents of mine gas prevention and control work. However, the hydrogeological conditions of mines in my country are extremely complex, and most coal seams are located in water-rich coal measures. In the process of coal seam gas pressure measurement, formation water intrusion into boreholes will seriously affect the success rate of gas pressure measurement. The main solution to pressure measurement drilling for formation water intrusion is to improve the quality of hole sealing. However, the current hole sealing technology is poor, and due to the complexity of the geological conditions on site, most of the piezometric boreholes located in the water-rich coal-measure strata cannot be effectively sealed, which seriously affects the accuracy of gas press...

AI Technical Summary

Problems solved by technology

However, this method only puts the borehole water under normal pressure conditions, and measures the amount of methane desorption in the borehole water by reducing the pressure, ignoring the amount of methane dissolved under normal pressure, because the formation water contains a certain amount of Soluble organic matter, which increases the amount of methane dissolved in water through hydration

Therefore, it is difficult to completely resolve the dissolved methane in the borehole water by using the conventional pressure reduction method, which affects the accuracy of the measurement results, and ultimately cannot accurately obtain the coal seam gas pressure value.

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