Numerical Modeling of Gas Migration and Hydrate Formation in Heterogeneous Marine Sediments
Numerical Modeling of Gas Migration and Hydrate Formation in Heterogeneous Marine Sediments
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非均质海洋沉积物中气体运移和水合物形成的数值模拟
DOI：
10.3390/jmse7100348
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发表时间：
2019
影响因子：
2.9
通讯作者：
Hailong Tian
中科院分区：
文献类型：
--
作者：
Keqi Bei;Tianfu Xu;Songhua Shang;Zilin Wei;Yilong Yuan;Hailong Tian
海底天然气水合物的形成受天然气运移聚集和水合物稳定带条件的控制。渗透率和孔隙度是评价天然气运移能力和储层封闭能力的重要因素，也是确定水合物在稳定区分布的重要因素。基于南海北方白云凹陷神湖地区现有的野外实测地质资料，采用数值模拟方法研究了孔隙度和渗透率非均质性对水合物形成和聚集过程的影响。模拟结果表明：（1）水合物稳定带的非均质性会影响甲烷在稳定带内的运移，进而影响水合物的形成和聚集。这是形成非均相水合物的原因之一。(2)当储层为层状非均质时，沉积物中天然气侧向运移和水合物形成存在层间差异，高孔高渗储层中水合物的水平分布范围较宽。(3)确定储层中水合物的优势富集区，应综合考虑沉积层的垂向和侧向条件，综合考虑水合物稳定区、储集空间和天然气运移排采条件之间的空间耦合配置关系。研究结果有助于进一步认识南海北方陆坡神湖地区水合物成藏规律，为今后水合物勘探和储量估算提供一定的参考。
The formation of marine gas hydrates is controlled by gas migration and accumulation from lower sediments and by the conditions of the hydrate stability zone. Permeability and porosity are important factors to evaluate the gas migration capacity and reservoir sealing capacity, and to determine the distribution of hydrates in the stable region. Based on currently available geological data from field measurements in the Shenhu area of Baiyun Sag in the northern South China Sea, numerical simulations were conducted to estimate the influence of heterogeneities in porosity and permeability on the processes of hydrate formation and accumulation. The simulation results show that: (1) The heterogeneity of the hydrate stability zone will affect the methane migration within it and influence the formation and accumulation of hydrates. This is one of the reasons for the formation of heterogeneous hydrates. (2) When the reservoir is layered heterogeneously, stratified differences in gas lateral migration and hydrate formation will occur in the sediment, and the horizontal distribution range of the hydrate in a high porosity and permeability reservoir is wider. (3) To determine the dominant enrichment area of hydrate in a reservoir, we should consider both vertical and lateral conditions of the sedimentary layer, and the spatial coupling configuration relationships among the hydrate stability region, reservoir space and gas migration and drainage conditions should be considered comprehensively. The results are helpful to further understand the rules of hydrate accumulation in the Shenhu area on the northern slope of the South China Sea, and provide some references for future hydrate exploration and the estimation of reserves.