Numerical Study of Hydrate Dissociation and Heat Stimulation by Hot Water Injection in Gas Hydrate Reservoirs

Abstract

Hot water injection has been a simple and promising method of thermally stimulating the extraction of hydrates, which promotes the dissociation of natural gas hydrates and improves gas production. However, the temperature region influenced by injecting hot water requires further research and evaluation. In this study, a computational model of the temperature field in the hydrate reservoir during hot water injection with the finite volume method, considering coupled gas–liquid two-phase flow, heat conduction, and hydrate dissociation, was developed. The model focuses on hot water injection vertical wells completed with slotted liners in the Shenhu Sea area hydrate reservoir, which can consider the heterogeneity of porosity, permeability, and saturation. It also analyzes the effects of injection volume, injection rate, hot water temperature, and other factors on the variations in temperature and pressure distribution. The results indicate that selecting the appropriate injection volume, the temperature of hot water, and the injection rate can promote hydrate decomposition and expand the range of heat stimulation reservoir temperature. Reservoir heterogeneity leads to heterogeneity of the hydrate dissociation front and temperature influence range, and the influence range of heat stimulation is larger than homogeneous reservoir.