The pilot study on start pressure of the air compressor during the air-lift reverse circulation drilling

With the development and improvement of drilling technique, air-lift reverse circulation drilling is widely used in different fields. The reasonable drilling technical parameters are crucial when used in current coal exploration and development. Based on the structure characteristics of double wall drilling tools, the critical velocity model is solved when cuttings are discharged by lifting of air-lift reverse circulation drilling under Newton's second law. Considering the loss along the way and the loss of local resistance of compressed air, the paper established the start pressure model of the air compressor for the air-lift reverse circulation in accordance with the law of conservation of energy. At last, the paper calculated the influencing factors of start pressure of the air compressor by using Matlab, the results show that the depth of the well, the depth of the air-liquid mixer and submergence ratio all have impact on the start pressure of the air compressor. The paper provides the foundation for determining a reasonable start pressure and also provides a reasonable basis for choosing the optional air compressor. The research on the start pressure model of air-lift reverse circulation is meaningful for optimal and fast drilling.