Numerical simulation for hydrate exploitation by depressurization in conjunction with hot brine injection with Five-Point Pattern

It is more profitable for the natural gas hydrate exploitation by use of the depressurization in conjunction with hot brine stimulation. In the work, at the initial stage of the exploitation, the depressurization is used to induce the hydrate dissociation. When the temperature drops and causes the decrease of the hydrate dissociation rate, hot brine is injected to prompt the hydrate dissociation, and furthermore accelerates the production rate of methane gas in the production well. We employ the Five-Point Pattern, a traditional method for the crude oil and gas production, to simulate the process of hydrate exploitation. The simulation results indicate that the most efficient stage of gas production is the depressurization process. The location of intense dissociation activity is in the area around the production well. During the hot brine injection into the well, the gas released from hydrate dissociation in the vicinity of the well moves towards the well, and the gas production rate from the well accelerates with increase of the gas saturation in the entire reservoir. The sensitivity analysis demonstrates the dependence of production on the intrinsic permeability of the reservoir.