Numerical Study of the Gas Production Enhancement Effect of Boundary Sealing and Wellbore Heating for Class 1 Hydrate Reservoir Depressurization with Five-Spot Wells

Natural gas hydrates (NGHs) are a promising alternative energy source with huge global reserves, but they face significant challenges in commercial production and require more efficient exploitation methods. Based on field data from China’s first offshore NGH pilot production, this study systematically investigates the enhancement effect of boundary sealing and wellbore heating on the development of Class 1 hydrate reservoirs with five-spot wells. Numerical simulation findings illustrate that when the sealing layer thickness is 1 m and the permeability is 0.001 mD, it can effectively expand the radial propagation of pressure, promote the gas output, and significantly reduce water production. When the heating power is 100 W/m, the highest energy efficiency ratio can be achieved, which can promote dissociation and inhibit the secondary hydrate generation. The combination of two technologies shows a synergistic effect, which increases the cumulative gas production and gas-to-water ratio to 197.4% and 224.3% of the base case, respectively, achieving the optimal balance between high recovery rate and economic efficiency, which provides key insights for the effective development of Class 1 hydrate reservoirs.