Analysis of Annular Pressure Generation Mechanism and Research on Safety Evaluation Yingying Zhang, Wei Rong, Weiyi Xie, Qilun Liu, Xixi Chen, Liangwen Liu and Xu Zhang E3S Web Conf., 261 (2021) 01057 Published online: 21 May 2021 DOI: 10.1051/e3sconf/202126101057