Application of Dual Horizontal Well Systems in the Shenhu Area of the South China Sea: Analysis of Productivity Improvement

Abstract

The horizontal well technology was successfully applied in the Chinese second natural gas hydrate (NGH) field test in the Shenhu area of the South China Sea in 2020. However, the results show that the threshold for commercial exploitation has not been broken, judging from daily gas production and cumulative gas production. Consequently, the paper presents the effects of dual horizontal well systems for exploitation in this area. The NGH reservoir model in the Shenhu area was established with CMG software. The influence of various layout options and various spacing of dual horizontal well systems on the production capacity was investigated. Further, we simulated the production effect of dual horizontal well systems joint auxiliary measures, such as well wall heating, heat injection, etc. The results show that the production capacity of dual horizontal well systems increased by about 1.27~2.67 times compared with that of a single horizontal well. The daily gas production will drop significantly, no matter which method was used, when exploitation lasts for about 200 d. Meanwhile, well wall heating and heat injection have limited effects on promoting production capacity. In conclusion, attention was drawn to the fact that the synergistic effect could be fully exerted to accelerate NGH dissociation when dual horizontal well systems are applied. The NGH reservoirs in the Shenhu area may be more suitable for short-term exploitation. The research results of this paper can provide a reference for the exploitation of the Shenhu area.