边、底水气藏水侵规律可视化实验研究

Visual simulation experimental study on water invasion rules of gas reservoir with edge and bottom water

针对边、底水气藏开发过程中的水侵问题,根据不同类型气藏的主要储集空间特征设计相对应的可视化物理模型,并利用水侵规律物理模拟实验系统开展了孔隙型、裂缝型、孔洞型和缝洞型气藏水侵规律可视化实验研究。结果表明:孔隙型气藏采出程度高,水侵前缘近似均匀推进,见水后水气比增加缓慢;水体在裂缝型气藏中优先沿着裂缝快速突进,同时在毛细管力和润湿性的作用下,储层基质发生渗吸,封闭基质中的气体,在缝网中间形成大量残余气,造成裂缝型气藏采出程度的大幅下降;储层中孤立的洞和缝主要为气藏提供储集空间,水体优先进入洞和缝,在局部对水侵影响较为显著,但对整体水侵前缘的推进影响不大;缝、洞沟通的气藏,水体沿着裂缝快速的充满洞,当出口端通过缝、洞与边、底水沟通时,气藏将在短时间内因为水淹而停产,此时气藏仅仅动用了缝和洞中的气体。研究成果对边、底水气藏的有效开发具有指导和实践意义。

In view of the water invasion in development of gas reservoir with edge and bottom water,the visual physical experiment model is designed based on the main reservoir space characteristics of different types of gas reservoirs,and physical simulation experiment system is used to research the water invasion rules of pore type,fracture type,hole type and fracture-cavern type gas reservoir.The result shows that pore type gas reservoir recovery degree is high,the leading edge of water is approximately uniform advance,and water-gas ratio increases slowly after water breakthrough.Water goes in priority in a quick dash along the fracture,gradually invades matrix by the capillary force and block the gases in the matrix,so a large amount of gas is blocked in the fracture gas reservoir,which leads to sharp fall of fracture type gas reservoir recovery degree.The isolated holes and cracks in reservoir mainly provide storage space,and water first goes into the hole and slot,which has significant influence on local water invasion,but has little effect on the whole water invasion＇s propulsion.The gas reservoir is linked by cracks and holes,water swiftly fills holes along the cracks.When the outlet contacts with the edge and bottom water through cracks and holes,gas reservoir will be shut down because of the water in a short time.At that time the gas reservoir only use the gases in the seams and holes.The results of research have important guidance and practical significance for the effective development of edge and bottom water reservoir.