天然气水合物分解机理及调控方法研究

The exploitation of natural gas hydrates will involve complex thermophysics processes, such as gas hydrate dissociation, reservoir deformation, multiphase porous flow and heat and mass transfer, in multiphase and multicomponent sediment system. And these complex thermophysics processes interact each other. This is a main difficulty for natural gas hydrates exploitaion. In this proposal, all studies will aim on the exploitation of the natural gas hydrates deposits in the Northern South China Sea. The combined testing and characterization techniques of multiparameters will be employed in our research. The key research contents include: the hydrate dissociation mechanisms and phase change law, the responding mechanisms caused by the structural change of the sedimentary layer，the mechanisms of multiphase seepage and heat and mass transfer, as well as the coupling mechanisms of multi-thermophysics processes. The research involves microscopic characteristics of different phase transition, sedimentary structure change characteristics, macro-scale physical experiment，theoretical modelling, and field-scale numerical simulation. Through the combination of these multi-scale studies, the following key scientific issues will be solved. They include the interaction mechanisms of gas-water-hydrates-sediment in the hydrate deposits, the change law of the mechanical properties of the sediments, the trigger mechanisms of reservoir deformation and collapse and sand production, the mutual coupling mechanisms of hydrate dissociation, reservoir deformation, multiphase porous flow and heat and mass transfer during the natural gas hydrates exploitation. The hydrate dissociation and control mechanisms during the natural gas hydrates exploitation will be illustrated. A new natural gas hydrate exploitation theoretical model, which could accurately describe all thermophysics processes of the natural gas hydrates exploitation, will be obtained after this study. And the fundamental theory of the natural gas hydrates exploitation and its control theory will be established when the project finishes. The research will provide theoretical and technical supports for the exploitation and utilization of natural gas hydrate resources in the South China Sea. The research results will have important scientific significance and application value.

针对多相多组分沉积物体系天然气水合物分解、储层变形、多相流动、热质传递等复杂热物理过程相互作用的难点问题，以我国南海北部天然气水合物藏为目标，采用多参数联合测试与表征方法，重点研究水合物分解反应机理及相态变化规律，分解过程沉积层结构变化的响应机制，分解过程多相渗流与热质传递影响机制及多种热物理过程耦合机制等；通过微观相态变化特性、沉积层结构变化特性研究、室内物理模拟实验和理论模型及矿藏尺度数值模拟相结合，研究解决气-水-水合物-沉积物相互作用机制，沉积层力学性能变化规律及储层变形-塌陷、产砂机理及触发机制，水合物分解反应、沉积层结构变化、多相渗流、热质传递四者相互耦合机制等关键科学问题；揭示水合物分解机理及调控机制；建立精确描述水合物开采过程多种热物理过程的新型开采数值模型和开采与控制基础理论体系，为我国南海水合物资源开发利用提供理论与技术支撑，具有重要科学意义和应用价值。

随着我国南海天然气水合物资源现场试采的顺利实施，建立水合物开采与安全控制理论与技术体系，是实现水合物商业开采的关键。本项目针对我国南海水合物成藏环境，自主研发了9套试验设备；完成了沉积物中水合物生成和分解特性实验，建立水合物体系SAFT-MSA-LJ分子热力学方程和分形-缩核分解动力学模型，获得水合物分解过程中气-水-水合物-多孔介质之间的相互作用规律，揭示水合物分解过程热力学与动力学机制；完成了水合物分解过程沉积层结构变化力学实验，阐明水合物对沉积物的胶结作用机理，揭示分解过程沉积物颗粒重排、旋转、滑移等变形机理；完成水合物分解过程中气-水-砂运移规律研究，阐明水合物分解产砂机理，建立了水合物分解产砂控制方法。完成水合物生成和分解过程沉积层渗透率和导热系数测量实验，建立了沉积物中渗透率和水合物分解过程沉积层中导热系数预测模型，揭示水合物分解的热质传递机制；完成不同分解方式、多井网模式下水合物分解实验研究，揭示水合物分解、固相运移、热质传递、以及多场耦合（分解-传热-流动）机制；提出温度场、流体场、力学场和化学场多场耦合模型和“人工井壁”强化低渗透水合物藏开采方法，完成南海水合物藏开采数值模拟研究，优化水合物开采方法；开发全隐式天然气水合物开采模拟器，完成我国南海水合物矿藏野外试采过程模拟计算。项目研究为我国南海天然气水合物资源开发利用提供基础数据、理论和技术支持，为天然气水合物领域产学研合作创新提供了有力支持和重要参考。发表学术论文161篇，其中SCI收录论文112篇；申请中国发明专利37件（授权23件）、美国发明专利6件（授权6件）、国际PCT专利13件；出版学科专著1本，软件登记1件；培养1名国家优秀青年基金支持者，1名“第六批国家高层次人才特殊支持计划青年拔尖人才”等青年人才；获国家技术发明奖二等奖1项，广东省自然科学奖一等奖1项等奖励。