Ding Tingji, Wang Ruihe, Xu Jiafang, Camara Moussa, Zhou Weidong, Zhang Jun
School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, 266580, People's Republic of China.
Key Laboratory of Unconventional Oil & Gas Development, Ministry of Education, China University of Petroleum (East China), Qingdao, 266580, People's Republic of China.
J Mol Model. 2022 Mar 31;28(4):109. doi: 10.1007/s00894-022-05070-6.
The formation of gas hydrate is a serious threat to the safe and effective completion of deepwater drilling and transportation operations, although it is considered as a potential energy resource. The inorganic salts are generally used as thermodynamic inhibitors; CaCl as a common additive in drilling fluids exhibits unique properties. In this study, we explored the dissociation mechanism of CH hydrate in CaCl solutions at the macroscopic and microscopic scale using experiment and molecular dynamics (MD) simulation. The experimental results showed that CaCl accelerated the dissociation rate of CH hydrate. The dissociation rate of CH hydrate increased with the increase of CaCl concentration at large depressurization pressure and was mainly affected by pressure when the depressurization pressure was lower. MD simulations were used to give an atomic scale interpretation of the macroscopic results obtained from the experiment. The results showed that the addition of CaCl destroyed the resistance liquid film formed during CH hydrate dissociation, thus accelerating the dissociation process, in good agreement with experimental results. HIGHLIGHTS: • The amount of CaCl affects CH hydrate dissociation at large depressurization pressure. • The dissociation of CH hydrate at low depressurization pressure is dependent on pressure. • Ca destroys effectively the resistance liquid film produced during hydrate dissociation. • MD simulation results are in agreement with those of the experiment.
尽管天然气水合物被视为一种潜在的能源资源，但其形成对深水钻井和运输作业的安全与有效完成构成严重威胁。无机盐通常用作热力学抑制剂；氯化钙作为钻井液中的常见添加剂具有独特性能。在本研究中，我们通过实验和分子动力学（MD）模拟，从宏观和微观尺度探究了氯化钙溶液中甲烷水合物的分解机理。实验结果表明，氯化钙加速了甲烷水合物的分解速率。在较大降压压力下，甲烷水合物的分解速率随氯化钙浓度的增加而增大，而在较低降压压力下，主要受压力影响。MD模拟用于对实验获得的宏观结果进行原子尺度的解释。结果表明，氯化钙的加入破坏了甲烷水合物分解过程中形成的抗性液膜，从而加速了分解过程，与实验结果吻合良好。要点：• 在较大降压压力下，氯化钙的量影响甲烷水合物的分解。• 在较低降压压力下，甲烷水合物的分解取决于压力。• 氯化钙有效破坏了水合物分解过程中产生的抗性液膜。• MD模拟结果与实验结果一致。
