Production Response of Marine Hydrate Reservoirs to Key Seepage Parameters Under Depressurization Conditions

Numerical simulation serves as a pivotal method for forecasting the production behavior of hydrate reservoirs, where seepage parameters frequently govern the discrepancies observed in predictive outcomes. In this study, we investigated the influence of fundamental seepage parameters on the productivity of hydrate reservoirs. Taking the hydrate reservoir in the QDNB as a case study, a stratified reservoir model was established to represent the coexistence of free gas and hydrates. By employing the Tough + Hydrate simulator, the production characteristics of the reservoir at site W03 were systematically analyzed. Results demonstrated that n_G plays a pivotal role in influencing wellhead gas production, with an inverse relationship observed between gas production rate and n_G. Moreover, the wellhead gas production rate is positively correlated with S_irA, while the water production rate inversely correlates with S_irA. A decrease S_irG enhances hydrate decomposition and augments gas production within the reservoir. Cumulative gas production at wellhead increases exponentially as the n_G decreases, while cumulative water production escalates with a decrease in the n_A. Lower n_G and n_A facilitate more efficient hydrate decomposition within the reservoir. Sensitivity analysis underscores that the impact of seepage parameters on wellhead gas production diminishes in the sequence: n_G, S_irG, S_irA, and n_A. Conversely, for wellhead water production, n_A emerges as the predominant factor, succeeded by S_irA, with S_irG having the minimal impact.