Effects of a Multistage Fractured Horizontal Well on Stimulation Characteristics of a Clayey Silt Hydrate Reservoir.

Abstract

The gas production from clayey silt natural gas hydrate (NGH) reservoir in the South China Sea faces the problem of low connectivity between the reservoir and the production well, which seriously reduces the gas production rate. Multistage fractured horizontal well (MFHW) is regarded as an effective technical means to improve gas production for an unconventional reservoir with low permeability. In this paper, a three-dimensional numerical simulation model was built to study the promotion effects of MFHW technology on gas production from a clayey silt NGH reservoir. The temporal and spatial evolution characteristics of the NGH reservoir with and without multiple fractures were compared and analyzed in detail. In addition, the influences of the fracture number, permeability, and morphology on the stimulation effect on gas production through MFHW technology were discussed. The results indicated that the fractures with high conductivity provided a fast channel for gas and water flow and increased the contact area between the horizontal well and the NGH reservoir, which had a positive effect on increasing gas production from the clayey silt NGH reservoir. Increasing fracture number, fracture permeability, and the area of fracture morphology effectively improved the gas production rate and total gas production, but the stage of the high gas production rate only lasted for a short time. This study demonstrated the production behavior of MFHW technology in the clayey silt NGH reservoir, which was helpful for understanding this technology’s stimulation effect.