Gas Production and Sediment Response in Marine Hydrate Reservoirs after the Invasion of a Novel Fracturing Fluid

Hydrate-bearing clayey-silty reservoirs in the South China Sea are characterized by weak cementation, low strength, and low permeability. Therefore, enhancing hydrate extraction efficiency and improving sediment deformation resistance through reservoir stimulation is essential. In this study, we developed a novel fracturing fluid (dual-enhanced slurry) aimed at enhancing gas production efficiency and strength via hydraulic fracturing and slurry injection. Conventional fracturing fluids typically weaken reservoirs and reduce gas production efficiency by invading the formation. This study investigates the gas production and sediment deformation following the invasion of the dual-enhanced slurry during the depressurization and hydrate decomposition process, comparing the results with noninvasion conditions through laboratory experiments. The results demonstrate a significant increase in the deformation resistance of the invaded sediments, with strengths reaching up to 5 times higher than those of noninvaded sediments. Notably, the strain rate of the sediments following dual-enhanced slurry invasion was significantly lower, with reductions of up to 48% compared to the noninvaded sediments. Furthermore, the peak gas production rate during hydrate decomposition can reach 1.68 times that of the noninvasive condition, and the gas production can reach 1.36 times that of without invasion. During hydrate decomposition, the gas production rate decreased with increasing effective pressure but increased with higher sediment porosity. Additionally, as a large amount of permeability enhancer in the slurry consolidating body was discharged, gas production increased by 1.54 times compared to nondischarged samples, and the peak gas production rate was 3.4 times higher than that of the nondischarged samples. These findings highlight the potential of the dual-enhanced slurry to not only improve hydrate extraction efficiency but also provide insights into optimizing future reservoir stimulation techniques.