Deformation Coupled Effective Permeability Change in Hydrate-Bearing Sediment during Depressurization
Deformation Coupled Effective Permeability Change in Hydrate-Bearing Sediment during Depressurization
复制标题
降压过程中含水合物沉积物变形耦合有效渗透率变化
DOI：
10.3390/pr10112210
复制
发表时间：
2022-10
期刊：
影响因子：
3.5
通讯作者：
Kenichi Soga
中科院分区：
文献类型：
--
作者：
Xiang Sun;Hao Luo;Kenichi Soga
在深海和永久冻土区的沉积物中发现的甲烷水合物引起了全球的关注。减压井的产气率取决于井筒周围含水合物沉积物的有效渗透率。在降压过程中，孔压的降低导致土壤压实和水合物解离，从而导致有效渗透率的动态变化。为了更详细地描述有效渗透率的变化，本研究提出了一种简单的可压缩性-渗透率耦合分析方法来识别减压后有效渗透率增加或减少的条件。推导了考虑水合物解离和土体压实的有效渗透率随孔压和温度变化的解析解。研究发现，在充足的供热条件下，水合物解离过程中有效渗透率主要由水合物解离主导，而水合物解离后，土壤压实是渗透率变化的主导因素。但在供热不足的情况下，压实作用主要决定渗透率，水合物分解作用有限。这项工作将有助于储层的快速评价。
Methane hydrates found in the sediments of deep sea and permafrost regions draw global interest. The rate of gas production from a depressurized well is governed by the effective permeability of the hydrate-bearing sediments around the wellbore. During depressurization, a decrease in pore pressure leading to soil compaction and hydrate dissociation results in a dynamic change in the effective permeability. To describe the change in the effective permeability in detail, in this study, a simple coupled compressibility–permeability analysis method is proposed to identify the conditions under which the effective permeability increases or decreases after depressurization. An analytical solution is derived for the effective permeability change with pore pressure and temperature, considering hydrate dissociation and soil compaction. We found that when there is a sufficient heat supply, hydrate dissociation dominates the effective permeability during hydrate dissociation, but after hydrate dissociation, soil compaction is the governing factor for permeability change. When there is an insufficient heat supply, however, compaction mainly determines the permeability, and the effect of hydrate dissociation is limited. This work will be helpful for rapid reservoir assessment.