The "Stable Fluid Volume" Pressure Control Drilling Technology and Its New Progres

In order to solve the problems of complex pressure control drilling technology and multiple equipment matching, make pressure control drilling simple and easy to implement, and achieve balanced pressure drilling, starting from the monitoring and identification methods of pressure balance in the well, the relationship between pressure balance in the well and the current situation of pressure control drilling were analyzed. The principle, process and implementation method of "liquid volume stability" pressure control were studied, and the "constant liquid level" automatic control technology was formed to achieve automatic control in "liquid volume stability" pressure control drilling. The liquid level control accuracy on the drilling site was less than 25mm.The results show that adjusting the throttle valve according to the changes in the circulating tank liquid level during drilling to maintain "liquid volume stability" can achieve real-time balance between bottomhole pressure and formation pressure, and carry out balanced pressure drilling. In on-site applications, a 35MPa rotary blowout preventer was used, with a wellhead pressure not exceeding 7MPa as the principle, and manual throttling control was adopted to successfully drill through the pressure coefficient greater than 2.0, zero pressure window saltwater layer, and pressure coefficient greater than 1.80, zero pressure window limestone fractured gas layer, solving the drilling problem in Block B on the right bank of the Amu Darya River in Turkmenistan. Research has shown that compared with other pressure control methods, the supporting equipment of "liquid volume stability" pressure control drilling technology is greatly simplified, the pressure control process is simple, and it has good on-site application value.