裂缝性特低渗透油藏 CO₂驱封窜技术研究

Carbon Dioxide Flooding Channeling Blocking Technology in Fractured Low Permeability Reservoirs

周 游 李治平 张 磊 景 成 张志营 李 晓

ZHOU You LI Zhiping ZHANG Lei JING Cheng ZHANG Zhiying LI Xiao

为了提高裂缝性特低渗透油藏 CO2驱开发效果， 研发了一种将改性淀粉强凝胶和乙二胺联用的封窜技术。分别考察了改性淀粉凝胶体系（3%改性淀粉+3%丙烯酰胺+0.1%交联剂 N， N-亚甲基双丙烯酰胺+0.05%引发剂过硫酸铵）、 乙二胺体系（质量分数 13%的乙二胺水溶液）及二者联用时在 CO2驱的不同裂缝性特低岩心的封堵效果， 报道了改性淀粉强凝胶和乙二胺体系联用的应用效果。初始状态下， 改性淀粉体系具有牛顿流体特征， 可在大裂缝中均匀稳定推进， 成胶后为强凝胶， 黏度大于 20×104 mPa· s。乙二胺初始黏度与水接近， 与 CO2反应后生成白色固体颗粒或淡黄色黏稠物。改性淀粉强凝胶可以较好地封堵开启的大裂缝， 乙二胺体系可有效封堵闭合裂缝或基质窜流带。对于 40目的填砂大裂缝， 改性淀粉凝胶封堵前气体流量为 10000 mL/min， 封堵后降为 760 mL/min， 可提高采收率 21.8%； 对于闭合的微小裂缝， 乙二胺封堵前的气窜速率为 1950 mL/min， 封堵后降为 330 mL/min， 可提高采收率 18%。对气驱没有开发效果的裂缝性岩心， 先注入淀粉体系封堵大尺度后再注入乙二胺封堵小裂缝或高渗层可提高采收率 44%以上。矿场试验说明裂缝性特低渗油藏气窜后， 改性淀粉堵剂和乙二胺联用封堵窜流通道可大幅度提高采收率。图 3表 6参 10

A new kind of plugging technology which combined modified starch hard-gel and ethanediamine was developed in order to improve the development effect of CO2 flooding in fractured low permeability reservoirs. The plugging effect of the modified starch system，composed of 3% modified starch，3% acrylamide，1% cross-linking agent N， N-methylene bisacrylamide and 0.05% initiator ammonium persulfate，ethanediamine system with mass fraction of 13%，and combination of the modified starch system with ethanediamine system，was investigated，respectively，in the different fractured low permeability cores during CO2 flooding. Furthermore，the field application effect of combination modified starch system and ethanediamine was mentioned. Under the initial state，the modified starch possessed Newtonian fluid characteristics and could advance steadily in the great rift，and became strong gels after gel-forming and its viscosity was greater than 20×104 mPa·s. The initial viscosity of the ethylenediamine system was close to that of water，and white solid particles or pale yellow viscous material formed after reacting with CO2. The modified starch gel could block off the open great rift effectively，and the ethylenediamine system could block off the close crack or matrix fluid channeling zone. For the fractured cores with 40 mush，the gas flow rate was reduced from 10000 mL/min to 760 mL/min after plugged by the modified starch gel，and the recovery efficiency could be improved by 21.8%. For the tiny crevice，the gas flow rate was reduced from 1950 mL/min to 330 mL/min after plugged by the ethylenediamine system，and the recovery efficiency could be improved by 18%. For the fractured cores which had no development effect，the recovery efficiency could be improved by over 44% when injecting the starch system and successive ethylenediamine system. Field experimental results showed that when the fractured low permeability reservoirs was gas channeled，the method combining the starch plugging agent and ethylenediamine could greatly improve the recovery efficiency.

10.19346./j.cnki.1000-4092.2017.01.014