Enhancement of gas production from hydrate reservoir using a novel deployment of multilateral horizontal well

Most marine hydrates deposit in low permeable argillaceous sediments. However, the gas production rate of current field trials for hydrate reservoir is lower than the commercial criterion. To enhance gas production, a novel multilateral horizontal well was numerically investigated based on an unconfined hydrate reservoir in the Shenhu Area in the South China Sea. The investigation shows the novel deployment enhances gas production rate due to the enlarged dissociation region and a great quantity of stimulated hydrates. The release rate of gas from hydrate exceeds the production rate, 70% of produced gas is gaseous methane and water-to-gas ratio is favorable. For various factors, increasing the length and the number of lateral well significantly enhances the gas and water production rates, which raises about 30% with additional 100 m lateral well. The lateral well deployed in the middle of reservoir causes a high gas rate and low water rate, and the angle of the main and lateral wellbores (ANGMW&LW) slightly affects the gas production. The sequence of factor of the deployment on gas production herein is: well length, depth, spacing, ANGMW&LW. The commercial gas rate could be achieved with 22 groups of 1000 m length multilateral well. •A novel ‘fishbone’ multilateral horizontal well is adopted to exploit hydrate.•The main factor of the deployment on gas production is well length, depth, spacing.•The length and number of lateral wellbore highly enhance gas production.•A multilateral well in the middle of unconfined reservoir is most favorable.•The commercial criterion may be reach by 22 groups of 1000 m multilateral well.