Fractured natural gas hydrate (NGH) reservoirs are widely tested all over the world. Existence of fractures will aggravate the basin-scale heterogeneity in both NGH distribution and seepage properties and, therefore, inevitably challenge some of our former understanding on gas production. However, gas productivities of the fractured NGH reservoirs have not been evaluated so far due to the rare accessible logging data for detailed characterization of fractures. Gas production from the fractured NGH reservoirs is modeled and the differences made by position, width, and length of the single conducive fracture and the single hydrate-filled fracture (HFF), respectively, are systematically analyzed. Sequentially, randomly distributed fracture networks are also considered in the gas productivity estimation. Results show that the conducive fractures in the overburden influence water production dramatically. When hydrate-bearing layers (HBLs) are characterized with HFFs, there will be obvious secondary formation near the HFFs, which together with its initial high NGH saturation hinders the pressure dissipation and the gas migration, generally shortening the production duration and reducing the accumulated gas. When the overburden and the HBLs are characterized with a randomly distributed fracture network, input fluid from upward could enhance gas production to some extent and lead to a fluctuated gas productive rate.

中文翻译：

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压裂水合物储层产气：数值模拟和评价

裂缝性天然气水合物 (NGH) 储层在世界范围内得到广泛测试。裂缝的存在会加剧天然气水合物分布和渗流性质的盆地尺度非均质性，因此不可避免地挑战我们先前对天然气生产的一些认识。然而，由于可获取的用于裂缝详细表征的测井数据很少，因此迄今为止尚未对裂缝性 NGH 储层的产气量进行评估。对裂缝性 NGH 储层的天然气产量进行建模，并系统地分析了单个导流裂缝和单个水合物填充裂缝 (HFF) 的位置、宽度和长度的差异。随后，在天然气产能估计中也考虑了随机分布的裂缝网络。结果表明，上覆岩层中的有利裂缝对产水量有显着影响。当含水合物层（HBLs）以 HFFs 为特征时，HFFs 附近会出现明显的次生地层，再加上其初始的高 NGH 饱和度阻碍了压力消散和气体运移，普遍缩短了生产工期，减少了积气. 当上覆岩层和HBLs具有随机​​分布的裂缝网络特征时，向上输入流体可以在一定程度上提高产气量，导致产气率波动。加之其初始的高 NGH 饱和度阻碍了压力消散和气体运移，一般缩短了生产时间并减少了积气。当上覆岩层和HBLs具有随机​​分布的裂缝网络特征时，向上输入流体可以在一定程度上提高产气量，导致产气率波动。加之其初始的高 NGH 饱和度阻碍了压力消散和气体运移，一般缩短了生产时间并减少了积气。当上覆岩层和HBLs具有随机​​分布的裂缝网络特征时，向上输入流体可以在一定程度上提高产气量，导致产气率波动。