Numerical analysis on hydrate production performance with multi-well systems: Synergistic effect of adjacent wells and implications on field exploitation

Multi-well technology is an alternative method to achieve commercialization development of the gas hydrate, which further requires proper production strategies. However, its stimulation mechanisms remain unclear, especially the synergistic effects of adjacent wells, restricting the production strategy formulation. Thus, we established a 3D model to characterize multi-physics fields, flow characteristics, as well as productivity of hydrate reservoirs on a large scale. It can display the fluid flow in complex geometries, realizing the accurate characterization of the flow field during hydrate production with multi-well systems. Total productivity of optimal multi-well systems can be 1.44 times higher than all single wells independently, Meanwhile, physical fields and flow characteristics alter with the well position as well as well number. After that, an index Ise is proposed to realize the quantitative evaluation of the impact of synergistic effect on productivity. The impact of synergistic effect strengthens continuously versus duration time and well spacing. In addition, the occurring synergistic effect can increase productivity by promoting hydrate dissociation in expanded pressure drop areas. In contrast, the fluid resistance effect decreases the per-well produced gas and water due to inflow reduction induced by inter-well interference. Moreover, an estimation model is established to identify the proper well spacing for lower drilling costs and larger productivity. This work will enable the extended application of multi-well systems with the synergistic effect and further promote the efficient development of the gas hydrate.