Experimental study on methane hydrate formation in quartz sand under tri-axial condition
Experimental study on methane hydrate formation in quartz sand under tri-axial condition
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DOI：
10.1016/j.jngse.2020.103707
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发表时间：
2020-11
影响因子：
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通讯作者：
Q. Gao;Jianzhong Zhao;Zhenyuan Yin;Dong Yang;Chi Zhang
中科院分区：
文献类型：
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作者：
Q. Gao;Jianzhong Zhao;Zhenyuan Yin;Dong Yang;Chi Zhang
甲烷水合物（MH）被认为是最清洁的能源之一。其巨大的资源储量和高能量密度引起了科学界的广泛关注。MH形成的动力学行为和由此产生的水合物饱和度受形成过程的条件（如水气比（WGR）、压力（P）、温度（T）和NaCl的质量分数（XNaCl））的影响很大。为了更好地了解原位沉积金属氢化物的动力学行为，建立了一种新型的三轴卧式固定床反应器，在典型的海洋条件下合成金属氢化物样品。在相似的初始应力条件下（初始三轴应力为16.50 MPa，模拟海洋MH的上覆应力），进行了一系列MH形成实验，同时扰动其他关键因素（WGR、P、T和XNaCl），以研究它们的影响。结果表明，初始水煤气比、温度和NaCl的存在对初始水气混合条件下形成末期的MH饱和度有负面影响。在固定床反应器中MH的形成使初始XNaCl = 3.0 wt%增加到最大XNaCl = 5.29 wt%，并使MH平衡曲线向更严格的MH形成条件移动。从气体注入开始到反应器压力稳定（ΔP< 20 kPa/h），较高的压力促进CH 4转化为MH，并增加MH饱和度。较大的初始WGR（高于MH水合数= 5.75）和较高的压力导致诱导时间的减少。升高温度和NaCl的存在增加诱导时间。
Methane hydrate (MH) has been considered as one of the cleanest energy resources. Its huge resource reserve and high energy density have attracted widespread attention in the scientific field. The dynamic behavior of MH formation and the resulting hydrate saturation are greatly influenced by the conditions of the formation process, such as water-gas ratio (WGR), pressure (P), temperature (T), and the mass fraction of NaCl (XNaCl). To gain a better understanding of the kinetic behavior of the in-situ MH deposits, a novel tri-axial horizon fixed bed reactor was set up to synthesize MH samples under typical marine conditions. A series of MH formation experiments were conducted under similar initial stress conditions (initial tri-axial stress of 16.50 MPa to simulate the overburden stress of marine MH) while perturbing the other key factors (WGR,P,T,andXNaCl) to investigate their effects. The results show that MH saturation attained at the end of formation from an initial water-gas mixing condition was negatively affected by initial WGR,T,and the existence of NaCl. MH formation in the fixed bed reactor increases initialXNaCl= 3.0 wt% to a maximum ofXNaCl= 5.29 wt% and shifts the MH equilibrium curve to a more stringent condition for MH formation. Higher pressure promotes CH4conversion to MH and increases MH saturation from the start of gas injection to the time when the pressure of the reactor was stable (ΔP< 20 kPa/h). Larger initial WGRs (above MH hydration number = 5.75) and higher pressures result in a reduction of the induction time. Increasing temperature and the presence of NaCl increase the induction time.