低渗透油藏二氧化碳驱修正毛管数理论及参数优化  

Study on modified capillary number theory and its application in parameter optimization of CO_2 flooding in low permeability reservoirs

作　　者：伦增珉[1,2] 王锐[1,2] 吕成远[1,2] 王海涛[1,2] 周霞[1,2] 

机构地区：[1]中国石化海相油气藏开发重点实验室,北京100083 [2]中国石化石油勘探开发研究院采收率所,北京100083

出　　处：《油气地质与采收率》2016年第2期83-86,92,共5页Petroleum Geology and Recovery Efficiency

基　　金：国家"863"项目"二氧化碳提高石油采收率与封存关键技术研究"(2009AA063406)

摘　　要：由于注采压差较大,使得低渗透油藏二氧化碳驱注采井间同时存在混相、近混相和非混相3种状态,因此仅通过传统的最小混相压力来评价低渗透油藏二氧化碳驱效果存在较大的局限性。为此,综合考虑二氧化碳驱过程中的扩散作用、溶解膨胀作用、粘度降低作用、界面张力降低作用、气油粘度比与密度比变化及润湿性改善作用等,对传统的毛管数理论进行改进,建立了适用于低渗透油藏二氧化碳驱的修正毛管数理论。运用该理论,结合二氧化碳溶解前、后流体高温高压物性实验和不同条件下的长岩心驱替实验,评价并优化了腰英台油田低渗透油藏二氧化碳驱的注采参数。结果表明,目标油藏二氧化碳驱的临界毛管数为4.5×10^(-7)~6.0×10^(-7),二氧化碳驱的最佳注入速度为0.4 mL/min,最佳平均注入井底流压为28.84~33.43 MPa。自2011年4月起,将优化获得的注入压力和注入速度应用于腰英台油田腰西区块二氧化碳矿场试验,截至2015年3月,累积注气量为16.7×10~4m^3,累积增产原油19 253 t,取得了良好的开发效果和经济效益。Miscible,near-miscible and immiscible state coexist during CO_2 flooding in low permeability reservoirs due to the large injection-production pressure difference between injection well and production well. It is not suitable to utilize MMP to evaluate CO_2 flooding effect. So traditional capillary number theory was modified for the low permeability oil reservoirs considering diffusion effect,swelling,viscosity reduction,interfacial tension reduction,variation on viscosity ratio,density ratio and wettability. In combination of PVT phase behavior and displacement experiments of CO_2 flooding in low permeability long cores before and after CO_2 solution,the modified capillary number theory was utilized to optimize the injection-production parameters of CO_2 flooding in Yaoyingtai low permeability reservoirs. The results show that the critical capillary number exists and ranges from 4.5×10^(-7)to 6.0×10^(-7),and the optimum injection rate is 0.4 m L/min and the average injection pressure is 28.84-33.43 MPa for CO_2 flooding. The optimized injection-production parameters have been applied in CO_2 flooding pilot test in Yaoxi block in Yaoyingtai oilfield since April 2011. Till to March 2015,incremental CO_2 injection has achieved 16.7×10~4m^3,incremental oil production has surpassed 19 253 tons,which indicates the good development effect and economic benefit of CO_2 flooding.

关 键 词：低渗透油藏 二氧化碳驱 驱替特征 混相 临界毛管数 

分 类 号：TE357.42[石油与天然气工程—油气田开发工程]