天然气水合物资源量的一种估算方法——以南海北部陆坡为例

A METHOD FOR GAS HYDRATE RESOURCE ESTIMATION—AN EXAMPLE OF PRELIMINARY ESTIMATION OF GAS HYDRATES IN THE NORTHERN CONTINENTAL SLOPE,SOUTH CHINA SEA

根据天然气水合物物理化学相图平衡的基本原理,运用微积分学的基本理论,尝试一种新的天然气水合物资源量计算方法,并以南海北部陆坡为例对天然气水合物资源量进行了初步估算。天然气水合物稳定分布区可看成由许多微体积单元组成,对所有微体积单元进行累积积分计算出天然气水合物的分布体积;然后结合世界上已知天然气水合物分布的有关参数(如天然气水合物沉积层的孔隙度、天然气水合物的饱和度和水合系数)估算南海北部陆坡天然气水合物的潜在资源量。估算结果为,南海北部陆坡天然气水合物资源量约相当于标准条件下6.3×1013m3的天然气,这与美国Blake海底高原、日本Nankai海槽、美国墨西哥湾北部天然气水合物资源甲烷量的数量级(1013m3)一致,显示了南海北部陆坡天然气水合物资源的巨大前景。当然,南海北部陆坡天然气水合物的潜在资源量还有待于进一步调查核实。

In this paper one method for estimating gas hydrate potentials was put forward based on the general gas hydrate thermodynamics and the basic calculus theory; subsequently a preliminary estimation of gas hydrates possibly occurring in the northern continental slope of the South China Sea （SCS） was carried out. Firstly the gas hydrate potential area was divided into various micro-volume blocks, and the whole gas hydrate potential volume was calculated by the integral accumulations. Afterwards the multiplication of the gas hydrate potential volume by the relevant subsurface sediment porosity, gas hydrate saturation and the hydration coefficient, which are referenced to the world well-known gas hydrate parameterizations, was conducted to estimate the gas hydrate potential resource in the northern SCS. The calculated result approximately corresponds to 6.3 × 10^13 m^3 of methane at the STP. It means that the estimated gas hydrate amount is generally equivalent to the magnitude of the Blake Ridge offshore America, the Nankai Trough offshore Japan, and the northern Gulf of Mexico offshore America （10^13 m^3 of methane） respectively. This suggests a huge gas hydrate potential resource in the northern continental slope of SCS. Of course it still needs to be checked or confirmed by the field investigation.