Physical Simulation Experiment and Result Analysis of Automatically Controlled Killing in Ultra-Deep Well

Existing ultra-deep well overflow killing relies on manual control of the choke manifold, which suffers from a slow response and large wellbore pressure fluctuation, likely resulting in complex situations such as secondary overflow and leakage. In contrast, automatically controlled killing can achieve the stable control of overflow killing operations during drilling. Therefore, the automatic control method integrating “proportional, integral, and differential (PID) + displacement” double-layer synergic feedback was designed. The automatically controlled killing system for ultra-deep wells was developed, and the physical simulation experiment device for automatically controlled killing was established. The automatically controlled killing experiment was carried out under the conditions of constant target pressure, continuously changing target pressure, and sudden pressure interference. The experiment results show that the automatically controlled killing system can adjust the choke valve opening within about 30 s, and the range of choke pressure fluctuation is less than 0.02 MPa. Compared with manually controlled killing, the automatically controlled killing system possesses good stability, accuracy, response speed, and anti-interference ability. The results of the study provide theoretical basis for the safe killing for complex formations in ultra-deep wells.