南海天然气水合物水平井分层开采过程中地层变形规律研究

天然气水合物（NGH）被称作世界尚未能开发的最大矿物能源，试采表明水平井分层开采法将是其首要采矿工艺。水平井分层开采过程中地层变形规律攸关未来NGH开采的安全与效率，但研究是空白。中国拟主攻开采的南海NGH，其物藏达千亿吨级油当量，赋存于难采的弱胶结泥质粉砂层中。首先，针对南海NGH典型赋存条件，通过试样实验和细观数值计算，获得弱胶结NGH泥质粉砂型沉积物的弹性模量、泊松比及强度参数等，为后续研究提供基础数据。其次，建立大型细观数值计算模型和大型物理相似模拟实验模型，研究单一水平井、单排水平井、多排水平井分层开采过程中储层及上覆地层的破裂、沉降规律与特征，以及地层孔隙压力、骨架应力变化规律等。最后，总结上述规律和特征，揭示南海NGH水平井分层开采过程中地层变形规律，并建立相应的地层沉降预测模型，为NGH安全、高效开采提供技术支撑。研究成果对世界NGH安全、高效开采有重要理论意义和实用价值。

Natural gas hydrate (NGH) is recognized as the largest untapped mineral energy source in the world, and the trail indicated that the slice mining by horizontal well will be the primary hydrate mining method. The deformation laws of stratum during slice mining process by horizontal well is crucial to the safety and efficiency of NGH, but little research about that has been conducted. As the primary mining target, the NGH in the South China Sea shows the reserve of up to one hundred billion tons of oil equivalent and occurs in weakly cemented muddy silty reservoirs. Firstly, the Elastic modulus, Poisson's ratio and Strength parameters of weakly cemented NGH-bearing muddy silt are obtained through sample experiments and meso-numerical simulation based on the typical occurrence conditions of NGH in the South China Sea, which will provide the basic data for subsequent studies. Secondly, the large meso-numerical simulation model and physical similarity simulation experiment model are established, and the fracture and settlement laws and characteristics of the hydrate reservoir and overlying stratum, as well as the variation laws of pore pressure and skeleton stress during the mining process by single horizontal well, single row horizontal wells, and slice mining process by multi-row horizontal wells separately. Finally, the above laws and characteristics are summarized, and the deformation laws of stratum in the South China Sea during slice mining process by horizontal well are revealed, and the corresponding stratum settlement prediction model is established to provide technical support for the safe and efficient mining of NGH. The research results will show important theoretical significance and practical value for the safe and efficient mining of NGH in the world.