Abstract About half of US natural gas comes from gas shales. It is valuable to study field production well by well. In early 2018, there were some 67,000 active horizontal gas shale wells in the US, some more than 12 years on production. Our approach is a hybrid between an unstructured big-data approach and physics-based models. We extend a previous two-parameter scaling theory of shale gas production by adding a third parameter that incorporates gas inflow from the external unstimulated reservoir. This allows us to estimate for the first time the effective permeability of the unstimulated shale and the spacing of fractures in the stimulated region. From an analysis of wells in the Barnett shale, we find that on average stimulation fractures are spaced every 20 m, and the effective permeability of the unstimulated region is 100 nanodarcy. We estimate that over 30 years on production the Barnett wells will produce on average about 20% more gas because of inflow from the outside of the stimulated volume. There is a clear tradeoff between production rate and ultimate recovery in shale gas development. In particular, our work has strong implications for well spacing in infill drilling programs.

中文翻译：

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现场数据提供对页岩有效渗透率、裂缝间距、井排水面积和增量产量的估计

摘要 美国大约一半的天然气来自气页岩。一口井地研究田间生产是很有价值的。2018 年初，美国约有 67,000 口活跃的水平气页岩井，其中一些已生产超过 12 年。我们的方法是非结构化大数据方法和基于物理模型的混合体。我们通过添加包含来自外部未增产储层的气体流入的第三个参数扩展了先前的页岩气生产的双参数标度理论。这使我们能够首次估计未增产页岩的有效渗透率和增产区的裂缝间距。通过对 Barnett 页岩井的分析，我们发现平均增产裂缝间隔为 20 m，未增产区域的有效渗透率为 100 纳达西。我们估计，在生产超过 30 年的时间里，由于来自增产体积的外部流入，Barnett 井将平均多生产约 20% 的天然气。在页岩气开发中，生产率和最终采收率之间存在明显的权衡。特别是，我们的工作对加密钻井计划中的井距具有重要意义。