Production performance of gas hydrate accumulation at the GMGS2-Site 16 of the Pearl River Mouth Basin in the South China Sea

In 2013, gas hydrate accumulations were confirmed in the Dongsha Area of the South China Sea by the scientific drilling expedition GMGS2. The drilling sites of GMGS2-01, -04, -05, -07, -08, -09, -11, -12, and −16 were verified with the existence of hydrate bearing layer. The gas production behavior was evaluated at GMGS2-16 by numerical simulation in this work. The scenarios of single depressurization with single horizontal well and dual horizontal wells and the depressurization in conjunction with warm brine stimulation with dual horizontal wells were carried out in this work. Simulation results indicated that gas production rate for the single depressurization with dual horizontal wells was higher than that for the single horizontal well. In addition, the gas production performance was more favorable when using the depressurization in conjunction with brine stimulation. The average gas production rate with such scenario can obtain the same order of magnitude with the minimum production level of the commercial viability of the hydrate exploitation in the Gulf of Mexico. Furthermore, the sensitivity analysis indicates that gas production rate increases with the increase of injection temperature. However, the energy loss increases with the rise of injection temperature. Increasing the injection salinity or the injection rate can increase the gas production rate as well. However, the energy ratio is the highest for the case with the middle-higher injection rate.