海底沉积物中热解成因天然气水合物的形成与分布

利用中国石油大学自制的一维天然气水合物成藏模拟装置,采用常规热解成因气为气源,海底沉积物为多孔介质,进行了水合物形成模拟实验,并采用电阻率法对沉积物中水合物形成与分布进行观测分析.结果表明,沉积物不同部位电阻率的变化不同,沉积物中下部电阻率先增加后趋于稳定,中上部电阻率呈降低-增加(或稳定)-降低-增加-稳定的变化趋势,这种电阻率的变化反映了不同部位的水合物的生成和分布.在中上部水合物诱导成核时,中下部已进入水合物生长阶段,由于温度梯度的影响,水合物生长缓慢,分散状分布;在气体供应充足的条件下,中上部水合物能大量生成,呈块状分布.在上述分析的基础上建立了沉积物中水合物生长与分布模式. 

Generation and distribution of thermogenic natural gas hydrates in submarine sediments

With an one-dimensional equipment designed by China University of Petroleum,the simulation of natural gas hydrate generation was carried out using conventional thermogenic natural gas as source and submarine sediment as porous medium.Resistivity method was applied to analyze the generation and distribution of natural gas hydrate in sediment.The results showed that resistivity varied between different positions of sediment.In the middle and lower position,resistivity first increased and then became stable.While in the middle and upper position,resistivity changed like zigzag,that was,decreasing,increasing(or stable),decreasing,increasing and stable.The changes of resistivity indicated the generation and distribution of natural gas hydrate in different positions.The natural gas hydrates in the middle and lower positions had come into being while those in the middle and upper positions were still during the induction and nucleation stages.Influenced by temperature gradient,natural gas hydrates generated slowly and scattered.If gas supplied sufficiently,natural gas hydrates might generate massively in the middle and upper positions.Finally,a hydrate generation and distribution model was established based on the above-mentioned analyses.