Abstract:

Based on geologic conditions of natural gas hydrate deposits, this paper used pT+H software and horizontal wells to evaluate gas production strategies including heat injection and combined use of heat injection and depressurization. This paper discussed the change of the saturation of gas hydrate, the saturation of CH4 in gas phase, the production rate of CH4 in gas phase, cumulative CH4 production, and water production when injecting water temperature is 30, 60 and 90 ℃. It was found that the distribution area of low hydrate saturation increases with increasing time and temperature, and the production rate of CH4 increases rapidly within 10 days and then decreases gradually. The results verified the advantages of combine method of heat injection and depressurization, and demonstrated the temperature is not sensitive to the production rate of CH4. It was found that cumulative CH4 volume in Shenhu area is not big mainly because of the low permeability. The findings can provide the references for gas production of natural gas hydrates in Shenhu area, the South China Sea or similar areas.

Key words: gas hydrate, horizontal well, production rate of CH4, heat injection and depressurization, TOUGH2, Shenhu area