Abstract Shale gas has received extensive attention and is becoming an important supplement to worldwide energy. Water is inevitable when developing shale gas with hydraulic fracturing. Thus it is necessary to understand the dynamic behavior of methane in water environments. Here, molecular dynamics simulations were performed to study the dynamic behavior of methane in the aqueous solutions with organic matters (OM). It is found that methane will accumulate at the OM-water interface and form a dense gas region spontaneously. The accumulation process is found to be little dependent on the gas saturation and the pressure within the simulating range, while it is closely related to the temperature and surface wettability. To explain the accumulation phenomenon of methane, the potential of mean force was calculated. We found that both the organic wall-gas interaction and the water-gas interaction are beneficial to the accumulation of methane and the former takes the leading role, while the gas-gas interaction impedes the accumulation. Our results imply the potentials of thermal exploitation and altering the surface wettability to enhance shale gas recovery. The dynamic behaviors of methane in aqueous solutions concerned in the present study are of great importance to estimate shale gas reserves, understand shale gas flow mechanisms and develop shale gas more efficiently.

中文翻译：

---

甲烷在水环境中有机物的积累行为

摘要 页岩气受到广泛关注，正在成为世界能源的重要补充。水力压裂开发页岩气时，水是不可避免的。因此，有必要了解甲烷在水环境中的动态行为。在这里，进行了分子动力学模拟以研究甲烷在含有有机物 (OM) 的水溶液中的动态行为。发现甲烷会在OM-水界面处积聚并自发形成致密的气体区域。发现成藏过程与模拟范围内的含气饱和度和压力无关，而与温度和表面润湿性密切相关。为了解释甲烷的积累现象，计算了平均力的潜力。我们发现有机壁-气相互作用和水-气相互作用都有利于甲烷的成藏，前者起主导作用，而气-气相互作用阻碍成藏。我们的结果暗示了热开采和改变表面润湿性以提高页岩气采收率的潜力。本研究涉及的甲烷在水溶液中的动态行为对于估算页岩气储量、了解页岩气流动机制和更有效地开发页岩气具有重要意义。我们的结果暗示了热开采和改变表面润湿性以提高页岩气采收率的潜力。本研究关注的甲烷在水溶液中的动态行为对于估算页岩气储量、了解页岩气流动机制和更有效地开发页岩气具有重要意义。我们的结果暗示了热开采和改变表面润湿性以提高页岩气采收率的潜力。本研究涉及的甲烷在水溶液中的动态行为对于估算页岩气储量、了解页岩气流动机制和更有效地开发页岩气具有重要意义。