可动凝胶迫使CO_2液流转向能力与增油机理研究
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摘要
为优化CO_2驱油技术,采用5组平行驱油实验探索研究两种不同性能凝胶对CO_2驱的增油效果及作用机理,通过采收率、气油比以及提出的冲刷系数综合分析CO_2凝胶复合驱的驱替特征。结果表明:注入段塞越大驱油效果越好,复合驱最终采收率比CO_2驱提升8.31～19.87个百分点;CO_2驱至气窜注入量约为0.3PV,而复合驱驱至气窜注入量需0.64～0.73PV,有效延缓了气窜时间;CO_2驱平均冲刷系数见气前为0.35cm~3·(cm~2·s·MPa)~(-1),见气后为0.75cm~3·(cm~2·s·MPa)~(-1),复合驱组注凝胶前平均冲刷系数为0.36cm~3·(cm~2·s·MPa)~(-1),后续CO_2驱降至0.092～0.188cm~3·(cm~2·s·MPa)~(-1),说明凝胶段塞封堵效果显著;复合驱机理分析表明:凝胶段塞赋予CO_2足够的液流转向能力是复合驱增油机理;凝胶在储层内的可动程度是调控液流转向能力的关键。
In order to optimize CO_2 flooding technology that 5 groups of contrast flooding experiments were conducted to investigate the effect and mechanism of two different properties of gel on CO_2 flooding. Then, the displacement characteristics of CO_2 gel composite flooding were analyzed by recovery, gas oil ratio and dynamic scour capacity. The results showed that with the increase of injection slug, the better the oil displacement effect, and the final recovery of composite flooding is 8.31～19.87 percentage points higher than that of CO_2 flooding;CO_2 flooding to gas channeling need injection CO_2 about 0.3 Pore Volume, but composite flooding needs 0.64～0.73 PV, so the gas channeling time was effectively delayed;The average scour capacity of CO_2 flooding is 0.35 cm~3·(cm~2·s·MPa)~(-1) before gas breakthrough, but 0.75 cm~3·(cm~2·s·MPa)~(-1) after gas breakthrough; the average scour capacity of composite flooding group is 0.36 cm~3·(cm2·s·MPa)-1 before injection gel, and the subsequent CO_2 flooding rapidly to0.092-0.188 cm~3·(cm~2·s·MPa)~(-1), It shows that the effect of gel plugging is remarkable. The mechanism analysis of composite flooding shows that the change of CO_2 flow direction by gel slug is the mechanism of compound flooding for increasing oil production; And the mobility of gel in reservoir is the key to control fluid diverting ability of CO_2.
In order to optimize CO_2 flooding technology that 5 groups of contrast flooding experiments were conducted to investigate the effect and mechanism of two different properties of gel on CO_2 flooding. Then, the displacement characteristics of CO_2 gel composite flooding were analyzed by recovery, gas oil ratio and dynamic scour capacity. The results showed that with the increase of injection slug, the better the oil displacement effect, and the final recovery of composite flooding is 8.31～19.87 percentage points higher than that of CO_2 flooding;CO_2 flooding to gas channeling need injection CO_2 about 0.3 Pore Volume, but composite flooding needs 0.64～0.73 PV, so the gas channeling time was effectively delayed;The average scour capacity of CO_2 flooding is 0.35 cm~3·(cm~2·s·MPa)~(-1) before gas breakthrough, but 0.75 cm~3·(cm~2·s·MPa)~(-1) after gas breakthrough; the average scour capacity of composite flooding group is 0.36 cm~3·(cm2·s·MPa)-1 before injection gel, and the subsequent CO_2 flooding rapidly to0.092-0.188 cm~3·(cm~2·s·MPa)~(-1), It shows that the effect of gel plugging is remarkable. The mechanism analysis of composite flooding shows that the change of CO_2 flow direction by gel slug is the mechanism of compound flooding for increasing oil production; And the mobility of gel in reservoir is the key to control fluid diverting ability of CO_2.
引文
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[2]窦宏恩,杨旸.低渗透油藏流体渗流再认识[J].石油勘探与开发,2012,39(5):633-640.
[3]王高峰,郑雄杰,张玉.适合二氧化碳驱的低渗透油藏筛选方法[J].石油勘探与开发,2015,42(3):358-363.
[4]孙庆和,何玺,李长禄.特低渗透储层微缝特征及对注水开发效果的影响[J].石油学报,2000,21(4):52-57.
[5]杨正明,张英芝,郝明强.低渗透油田储层综合评价方法[J].石油学报,2006,27(2):64-67.
[6]高云丛,赵密福,王建波.特低渗油藏CO2非混相驱生产特征与气窜规律[J].石油勘探与开发,2014,41(1):79-85.
[7]许姗姗,李虹,王天助.高温高矿化度油藏可动凝胶的研制及性能评价[J].重庆科技学院学报(自然科学版),2012,14(2):112-114.
[8]刘必心,侯吉瑞,李本高.二氧化碳驱特低渗油藏的封窜体系性能评价[J].特种油气藏,2014,21(3):128-131.
[9] Research on a novel composite gel system for CO2breakthrough[J].Petroleum Science,2010,7(2):245-250.
[10]王海栋.CO2驱气窜机理及封窜技术研究硕士论文[D].东北石油大学,2017:15-26.
[11]张海林,曹毅,刘峰刚. CO2驱复合凝胶封窜剂微观结构及配方优化[J].油田化学,2017,34(1):74-78.