The characteristics and implications of acidizing in clayey silt-type hydrate deposits

Natural gas hydrates are an energy resource with vast reserves; however, large-scale commercial development remains unrealized due to shallow burial depths and weak reservoir cementation. The primary hydrate reservoir type is clayey silt and sand production has been the main obstacle to its development. This study conducted consolidation and acidizing experiments using artificially prepared hydrate sediment samples to examine the injection behavior of consolidants and their effects on core properties. The results indicate that the low viscosity of the waterborne consolidant allows uniform injection into the core, effectively consolidating the sand grains. The optimal volumetric concentration of the consolidant (VCCA) was 50%, at which the compressive strength of the consolidated cores increased significantly, and no sand production occurred during acidizing. Although the consolidants reduce the porosity and permeability of the core, they significantly enhance the core's mechanical properties, ensuring reservoir stability. After acidizing stimulation, the permeability of the consolidated core was 64.28% higher than that of the unconsolidated core, with no sand production observed during the experiment, whereas the unconsolidated core exhibited severe sand production. This study explores chemical sand control technology for NGH reservoirs, offering new insights and references for the safe and efficient development of gas hydrate reservoirs.