天然气水合物降压开采实验研究

为了研究天然气水合物（NGH）降压开采基本规律,应用研制的NGH合成与开采实验系统,研究NGH降压开采的相平衡和基本生产规律.用图形法测定了4个NGH相平衡点,与已有文献数据吻合很好,说明了该实验装置和方法的可靠性.对于高孔高渗的多孔介质,相平衡数据与反应釜水溶液中相平衡数据一致,在进行NGH开采相平衡研究时,可以借用现有反应釜水溶液中NGH的数据和模型.在实验模型条件下,降压开采是比较好的NGH开采方法,产气速率较高且主要受压降速率控制.储集层压力控制和NGH自保护效应是实际NGH矿藏降压开采需要解决的关键问题.具有下伏游离气或同层伴生气的NGH矿藏,为克服以上两点不利提供了可能.另外,还可以考虑注热水、注化学剂等其他辅助强化开采措施.图5表2参15

Laboratory investigation of pressure development of natural gas hydrates

By using the formation and exploitation experimental apparatus of natural gas hydrates(NGH),the phase equilibrium and basic exploitation laws of NGH pressure development were investigated.Four NGH phase equilibrium points were determined by the graphics method.These data are very consistent with other researchers',showing that the experimental apparatus and method are reliable.For the porous media with high porosity and high permeability,the equilibrium curve of NGH is identical to that in water solution.Thus the equilibrium models and data of NGH in water solution can be used for the exploitation of NGH.Under the condition of this experiment,the pressure development of NGH is an effectual technique,which has a high gas production rate controlled by depressurization speed and a low water production rate.For NGH reservoirs,pressure control and self-protection are two key problems in the practical production.NGH reservoirs which have underlying free gas or associated gas make the two problems relatively resoluble.In addition,other enhanced oil recovery methods,such as chemical injection and hot-water injection,are also considerable.