Abstract:

Unlike conventional fossil fuels，such as coal，petroleum and natural gas，natural gas hydrate is a solid deposit present in deep and porous formation. Consequently the production of natural gas from natural gas hydrate is more difficult than that of conventional fossil fuels due to in situ decomposition of the hydrate，which requires energy input not only for the decomposition but also for temperature increase of the hydrate and the porous formation. These energy requirements inevitably reduce the effective energy obtainable from the hydrate and increase CO₂ emission intensity. Based on thermodynamic calculations and field data reported in the literature，this study analyzes energy consumption required in the production of nature gas from natural gas hydrate under various deposit conditions and compares its CO₂ emission intensity with that of conventional fossil fuels. It was found that natural gas production from natural gas hydrate has higher CO₂ emission intensity than that of petroleum and coal under different deposit conditions.

摘要：

与天然气、石油、煤等常规化石能源以富集态赋存、以赋存态开采不同，天然气水合物大都以固态分散赋存于地层的孔隙中，对其中所含天然气的开采要求水合物的原位分解。天然气水合物原位分解需要能量输入，既包括水合物的分解焓，也包括水合物和多孔地层（介质）升温所需的热量。由于天然气水合物的赋存条件差异很大，开采时水合物和多孔地层升温所需的热量不同，一些条件下天然气水合物的可利用能量（有效能量）会远低于常规天然气，单位有效能量所产生的总CO₂排放量甚至会高于石油和煤。为了量化认识这个现象，本文进行了天然气水合物开采能耗的热力学计算，分析了水合物赋存状况与产出天然气的有效（净）能量的关系，计算和讨论了不同赋存条件下天然气水合物在热能利用过程中的二氧化碳排放强度，并与常规化石能源进行了对比。