摘要
针对苏里格气田中北部苏53区块复杂的气水流动影响气井产能的问题,对目标储层的渗流规律开展研究。采用常规压汞、铸体薄片以及荧光薄片等技术手段,综合分析目标储层的孔隙结构特征,结合气水相渗实验与孔隙尺度下的气水两相数值模拟以及泄压实验,揭示苏里格中部致密砂岩储层开发过程中不同孔隙类型的气水渗流规律。结果表明:粒间孔-粒间溶孔、岩屑溶孔-粒间溶孔和岩屑溶孔-晶间孔为研究区主要的3类孔隙组合类型;流体在不同孔隙类型组合下的渗流规律差异明显;储层物性越好,两相共渗区越宽,等渗点处相对渗透率越高,束缚水饱和度越低;当驱替压力小于毛管阻力时,气相以水包气的形式赋存于孔喉中,阻碍水相流动,导致气水渗流能力大幅降低,形成低效共渗区;当驱替压力大于毛管阻力时,气水两相渗流能力最强,驱替时间最短。泄压实验表明:岩样孔隙类型越好,其泄压时间越短,压降幅度越大,采出程度越高;岩样孔隙类型越差,残留水越多,气体渗流能力越弱,采出程度越低;压汞与相渗结合结果表明,目标储层束缚水转变为可动水的生产压差界限为12 MPa。该研究结果对了解目标储层渗流规律有一定帮助,为苏里格气藏高效开发及后续开发方案的调整提供理论依据。
Aiming at the problem that the effect of complicated gas-water flow on the productivity of gas wells in central Su53,thin section and conventional mercury methods are used to analyze its characteristics of the pore structure.Based on the above experiments,the gas-water permeability experiment is combined with the two-phase numerical simulation at the pore scale to reveal it flow laws of central Sulige.The results show that the main types of the pore combinations in central Sulige are intergranular pore-intergranular dissolved pore,cuttings-dissolved pore-intergranular pore,and lithic-dissolved pore-intercrystalline pore.The seepage laws of fluids under different pore combinations are obviously different:the better the reservoir physical properties,the wider the two-phase permeability zone,the higher the relative permeability at the isotonic point,and the lower the irreducible water saturation.When the pressure of the displacement is less than the capillary resistance,the gas phase exists in the form of air-in-water,which hinders the flow of the water phase,resulting in the formation of a low-efficiency zone where the capacity of gas-water percolation significantly decreases.When the pressure of the displacement is greater than the capillary resistance,the gas-water seepage capacity is the strongest and the displacement time is the shortest.The research results are helpful to understand the percolation law of the target reservoir,and provide a theoretical basis for the efficient development of Sulige gas reservoir and the adjustment of subsequent development plans.
作者
李玉城
LI Yucheng(Geology Research Institute,CNPC Greatwall Drilling Company,Liaoning Panjin 024010,China)
出处
《非常规油气》
2022年第5期69-78,共10页
Unconventional Oil & Gas
基金
中国石油集团油田技术服务有限公司科技项目“苏里格高含水致密砂岩气藏效益开发关键技术研究”(2021T-02-01)。
关键词
渗流规律
孔隙类型
致密砂岩
两相共渗区
seepage law
pore type
tight sandstone
two-phase co-permeation zone
