海洋天然气水合物开采潜力地质评价指标研究：理论与方法

中国南海北部大陆坡具有良好的天然气水合物（以下简称水合物）资源前景，但目前还没有针对海洋水合物藏开采潜力的地质评价指标，无法对水合物藏进行简单高效的开采潜力评价预测。为此，重点分析了与产气潜力密切相关的地质参数（水合物层的孔隙度，水合物初始饱和度，储层渗透率，导热系数，储层上、下盖层的渗透性，储层的初始温度和初始压力）对产气潜力的影响情况。结果发现，在其他条件和参数不变的情况下：①水合物储层孔隙度越大，水合物分解产气速率越快；②水合物饱和度越高，初始产气效率较低，但总体产气开发效益较高；③水合物储层绝对渗透率越大，水合物分解和产气效率越高；④水合物储层导热系数对水合物分解产气效率影响不大；⑤盖层的存在有利于提高水合物的分解效率和气体的长期稳定生产；⑥水合物储层初始温度越高越有利于水合物快速分解；⑦当地层初始压力越高且离水合物相平衡边界越近时，水合物藏产气开发效率也越高。在此基础上，提出了水合物开采潜力地质评价指标研究的目标、内容、技术路线和方法。

A study of geological evaluation indicators for the exploitation potential of marine natural gas hydrates: Theory and methodology

There are good prospects of natural gas hydrate resources on the northern slope of the South China Sea. However, whether or not the gas hydrate will play a part in our energy strategy lies in whether or not it can be effectively extracted. Such real production will mostly rely on the full assessment of gas production potential from the marine hydrate deposits. Unfortunately, the relevant research costs are surprisingly high in the field tests alone, while the experimental simulation of hydrate production under high pressures is limited to a small scale presently, and can not fully characterize the gas production potential on a substantial reservoir scale. Thus it is the only way for hydrate production engineers to establish mining plans and calculate gas production potentials through numerical simulation. Because the gas production potential, however, is closely related to the complexity and dissimilarities of the hydrate reservoir characteristics, the production capacities must be evaluated by using different production methods for different types of hydrate reservoirs, which will inevitably raise the research cost. Therefore, based on the response relationship between hydrate production potential and different geological parameters of hydrate reservoirs, this paper discussed the geological parameters, which are most closely related to the gas production potential. Thus, a set of the objectives, contents and methods were presented for the geological evaluation indexes of marine hydrate production potential, providing the theory and methodology for the rapid evaluation of gas production potential in the marine gas hydrate reservoirs.