Numerical simulation and experiment on acid jet drilling with preset pipes

In order to solve the problem of precise stimulation of deep fractured-vuggy carbonate reservoirs, the research on acid jet drilling technology with preset pipes was carried out. A numerical model of acid jet drilling into carbonate rocks with preset pipes was established, the flow field structure of acid jet drilling was analyzed, and physical simulation experiments on acid jet drilling were carried out. The research results show that the acid jet from the preset pipe can realize stable drilling in the carbonate rock outcrop. When the drilling encounters a gap of 50-150 mm during drilling, the pipe body meets the strength conditions for stable drilling, leaving a hole diameter ranging from 18 mm to 26 mm. Combining with the analysis on the streamline in the model medium, it is found that, the hole expansion effect due to the acid solution is obvious, the displacement and the acid concentration are proportional to the drilling speed in local area, the acid reaction rate is the main factor affecting the hole diameter, the rock mechanical properties are highly correlated with the drilling speed and the hole diameter, and the drilling trajectory is in a straight line along the injection direction as a whole. The research results provide theoretical guidance and technical support for the application of the acid fluid drilling technology with preset pipes in radial horizontal wells in carbonate rock reservoirs.