Development of gasification agent injection tool for underground coal gasification

The underground coal gasification (UCG) technology is basically mature, but the influence of its own process and tools slows down its industrialization progress. This paper introduced the development and field test of two new UCG coiled-tubing gasification agent injection tools. The test results show that the two kinds of gasification agent injection tools ensure the injection point under control by conducting downhole temperature measurement and ground monitoring jointly. The problem that the tool is burnt by the backfire is solved by designing a backfire prevention device. To realize low pressure drop, the gasification agent flow channel inside the tool is designed optimally to keep the tool pressure drop not more than 0.5 MPa and the system pressure drop not more than 3 MPa. The tool overall has the characteristics of low pressure drop, high temperature resistance, backfire prevention and anti burning to satisfy the demand of the field test. This technology is a new achievement in the development of UCG technology and equipment in China. The research conclusions can provide technical reference for developing a new generation of UCG technology.