基于分流理论的低渗透油藏CO_2泡沫驱渗流模拟  

Flow modelling of CO_2 foam flooding in low permeability reservoirs based on fractional flow function

作　　者：苏玉亮[1] 姜妙伦 孟凡坤 詹世远 盛广龙 陈颖 SU Yuliang;JIANG Miaolun;MENG Fankun;ZHAN Shiyuan;SHENG Guanglong;CHEN Ying(School of Petroleum Engineering,China University of Petroleum,Qingdao 266580,Shandong Province,P.R.China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,P.R.China;The Third Gas Production Plant of Changqing Oilfield,Xi’an 017300,Shaanxi Province,P.R.China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580 [2]中国石油勘探开发研究院,北京100083 [3]中国石油长庆油田采气三厂,陕西西安017300

出　　处：《深圳大学学报（理工版）》2018年第2期187-196,共10页Journal of Shenzhen University(Science and Engineering)

基　　金：国家重点基础研究发展计划资助项目(2014CB239103);国家自然科学基金资助项目(51674276)~~

摘　　要：泡沫驱油体系在多孔介质中的渗流机理十分复杂,为准确认识CO_2泡沫驱油机理,揭示其渗流规律.本研究基于低渗透油藏CO_2泡沫驱渗流特征,考虑启动压力梯度及泡沫中表面活性剂的吸附,根据分流理论和物质平衡原理,将表面活性剂分别溶于水或CO_2,并在不同注入条件下,分别建立低渗透油藏CO_2泡沫驱一维渗流模拟模型.运用图解法进行求解,确定驱替过程中含水饱和度的剖面分布.油藏数值模拟结果验证了所建模型的有效性.对不同泡沫质量、表面活性剂分布情况下的曲线进行分析,结果表明,泡沫中含水率提高,泡沫质量变差,泡沫驱替前缘移动速度先增后减,存在最佳的含水饱和度使得驱替效果最好;泡沫混相驱替前缘移动速度随气相与液相中表面活性剂质量浓度之比的增大而增加,当其趋近于无限大时,驱替效果达到最优.The seepage mechanism of foam flow in porous media is very complicated.The purpose of this research is explaining the flooding mechanism accurately and revealing the seepage mechanism of CO2 foam flow in porous media.Based on the characteristics of CO2 foam flow in low permeability oil reservoirs,a novel model of CO2 foam flooding considering the effects of surfactant adsorption and threshold pressure gradient is established and solved using the fractional-flow function and the principle of material balance.We derive the fractional-flow solutions for the foam displacement to find the water-saturation distribution in system,in the two cases of surfactant dissolved in supercritical CO2 or in water,respectively.The numerical simulations are presented to verify the graphical solutions obtained from fractional-flow function.In addition,the controlling factors that control the mobility and moving velocity of the foam bank are investigated,and the optimal design of flooding process is proposed(in the context of idealized 1D displacements).As the water fraction of the injected foam increases with deterioration of foam quality,the velocity of the flooding front would first increase and then decrease.Therefore,the optimal water fraction can be expected to maintain the gas front slightly ahead of the foam front for best performance.The propagation of the foam front depends on both surfactant adsorption onto rock and the partitioning of surfactant between water and CO2.The optimal process can be reached while the ratio of surfactant concentrations dissolved in CO2 to that in water tends to zero.Our work can provide a theoretical basis for the design of CO2 foam process in field applications.

关 键 词：油气田开发工程 低渗透油藏 CO2泡沫驱 渗流特征 含水饱和度分布 分流理论 数值模拟 曲线分析 

分 类 号：TE348[石油与天然气工程—油气田开发工程]