Research Progress on Marine Gas Hydrate Reservoir Damage and Protection

As potential energy sources with abundant reserves, cleanliness, and high efficiency, marine natural gas hydrates and icy shallow gas have become important strategic alternatives for China’s energy structure transformation and energy security. However, during the development of hydrate reservoirs and icy shallow gas, due to the reservoir’s own characteristics such as non-diagenesis, weak cementation and high water cut, coupled with the coupled changes of multiple fields including temperature field, pressure field, fluid field, stress field and phase state during development, it is very easy to cause problems such as “three blockages” (sand plugging, ice plugging and water plugging). These problems lead to a decrease in reservoir permeability and productivity, and even wellbore blockage and failure, which seriously restrict the safe and efficient development of hydrates. This paper systematically sorts out the main damage types and formation mechanisms of marine natural gas hydrate reservoirs during development, focuses on analysing the coupling mechanism of sand plugging, ice plugging, and water plugging and their impacts on reservoir productivity, and points out that the skeleton instability and fluid migration behaviour caused by hydrate decomposition are the core factors inducing reservoir damage. On this basis, it summarises the current research progress in hydrate reservoir protection at home and abroad, covering key links such as drilling and completion fluid systems, sand control technology, anti-ice plugging technology and plugging removal and restoration technology, and proposes a “prevention-control-governance” trinity reservoir protection technology framework. It is necessary to accelerate the construction of a damage evaluation and early warning system suitable for the characteristics of natural gas hydrate and icy shallow gas reservoirs in the South China Sea, develop intelligent and adaptive sand control and anti-ice plugging technologies, and promote the research on the evolution mechanism of reservoir damage under multi-field coupling conditions, to provide theoretical support and technical guarantee for the large-scale, long-term and stable development of marine natural gas hydrates in China.