Numerical Simulation of Conductor Stability in Deepwater Hydrate-Bearing Formation

Abstract Deepwater natural gas hydrates have attracted widespread attention as a clean energy resource, but their decomposition process will significantly change the physical and mechanical properties of the formation, posing a threat to the stability of the casing during drilling. Deepwater natural gas hydrates have attracted widespread attention as a clean energy resource, but their decomposition process will significantly change the physical and mechanical properties of the formation, posing a threat to the stability of the casing during drilling. Based on the multi-physics coupling theory, this study comprehensively analyzes the impact of hydrate decomposition on formation stability and the bearing capacity of the conductor. A coupled model integrating gas-water two-phase flow, thermal fields, and mechanical fields is constructed using finite element software to simulate the stability changes of the conductor passing through hydrate-bearing formations. The results indicate that during the early stages of hydrate decomposition, pore pressure in the near-well region rises rapidly, and the stress on the bottom and surrounding formation of the conductor increases significantly, resulting in intensified formation settlement and substantial conductor displacement. As the decomposition proceeds, the pore pressure and stress distribution tend to be stable, and the conductor displacement changes gradually slow down; the decomposition rate, pore pressure, and temperature changes show obvious time correlation, with violent fluctuations in the initial stage and gradually stabilizing over time. This study elucidates the dynamic mechanism of hydrate decomposition's impact on conductor stability and provides theoretical support for optimizing deepwater drilling design and natural gas hydrate development.