The method for well-killing selection considering the formation overflow energy

The geological conditions in the deep and ultra-deep wells are complex, high temperature and pressure may cause overflow. After the overflow, the well needs to be shut down in time, and the appropriate well killing mode should be selected to re-establish the downhole pressure balance. In order to provide a scientific quantitative selection method, this paper presents a well killing selection method based on quantitative evaluation of overflow capacity. In this paper, the concept of formation overflow energy is proposed, which represents the power of overflow fluid under specific pressure differential. Furthermore, the formation overflow energy computation model is established to evaluate the formation overflow capacity quantitatively. Finally, the selection criterion of well killing method is given, with the pressure return method and the maximum allowable pressure and the critical flow overflow energy as the evaluation index. This method has been tested in the overflow well in middle Tarim region, with wide applicability and an accuracy of 93.75%, which is of guiding significance for selecting the well killing method on site and realizing safe drilling.