深圳大学学报理工版

以致密油气体积改造注入的压裂液为切入口,将表面活性剂复配至压裂液中,探索在压裂过程中改变储层基质润湿性,提高采收率的方法.基于接触角和界面张力测量,在压裂液中分别添加阳离子表面活性剂、阴离子表面活性剂和非离子表面活性剂,在不同润湿状态下对致密岩心进行渗吸物模实验.通过改变润湿反转前后的相渗曲线和毛管压力曲线,对该过程进行模拟研究.结果显示:仅依靠压裂液不能引起润湿反转,渗吸采收率仅为4.95%.添加表面活性剂后润湿性发生变化,渗吸采收率有大幅提高,其中阳离子表面活性剂改变润湿性的能力要好于非离子表面活性剂和阴离子表面活性剂; 考虑润湿反转的模型可对表面活性剂润湿反转过程进行较好描述,模拟结果与实验数据拟合较好; 现场一平台井压裂液中加入润湿反转剂DL-15后,体积压裂形成复杂裂缝,产量比邻井提高2～4 t/d.建议体积改造形成复杂缝网的前提下,在压裂液中添加表面活性剂,延长焖井时间,依靠停泵后的压差驱替和渗吸置换作用,提高开井后产量.

In view of the comparison of contact angle and interfacial tension, we study the performance of the method of enhanced oil recovery(EOR)by altering the wettability of reservoir rock surfaces through adding different types of surfactant into the fracturing fluids during hydraulic fracturing. Firstly, the cationic surfactant, anionic surfactant and nonionic surfactant, respectively, were added into fracturing fluids. Afterwards, the imbibition experiments for tight cores after treated with different surfactants were performed. Lastly, a numerical simulation was carried to model the effects of wettability alteration by changing relative permeability curves and capillary curves. The main conclusions have been summarized as follows:(i)Only fracturing fluids cannot bring wettability alteration with a recovery as just of 4.95%. However, fracturing fluids added with surfactants can bring the changes of contact angle, and the recovery can be increased to be 21.29%(anionic surfactant), 15.84%(nonionic surfactant)and 9.91%(cationic surfactant).(ii)The simulation results with different relative permeability and capillary curves can achieve excellent agreement with the experimental data, hence this numerical simulation can be an effective method to describe wettability alteration in this study.(iii)As for field application, the oil production rate of a multi-stage fractured horizontal well with added surfactants(DL-15)into the fracturing fluids can have about 2～4 t/d more than that of other wells.(iv)The practices to add appropriate surfactants into the fracturing fluids during hydraulic fracturing and extend the shut-in period after fracturing are recommended in order to improve oil production performance.

引言
1 致密岩心润湿反转实验
2 结果与讨论
3 润湿反转的模拟
4 现场应用
5 结论

图1 接触角测量及渗吸实验所用岩心柱示意图<br/>Fig.1 Core sample for contact angle measurement and imbibition experiment

图1 接触角测量及渗吸实验所用岩心柱示意图
Fig.1 Core sample for contact angle measurement and imbibition experiment

图2 润湿反转前后接触角变化<br/>Fig.2 Contact angle before and after wettability alteration

图2 润湿反转前后接触角变化
Fig.2 Contact angle before and after wettability alteration

图3 液体与原油间界面张力<br/>Fig.3 Interfacial tension between fluid and oil

图3 液体与原油间界面张力
Fig.3 Interfacial tension between fluid and oil

图4 不同类型液体下的渗吸采收率<br/>Fig.4 Imbibition recovery rates of different fluids

图4 不同类型液体下的渗吸采收率
Fig.4 Imbibition recovery rates of different fluids

$表1 压裂液与不同类型表面活性剂复配溶液下岩心实验结果<br/>Table 1 Experimental results of fracturing fluids and surfactant compounded solutions$

表1 压裂液与不同类型表面活性剂复配溶液下岩心实验结果
Table 1 Experimental results of fracturing fluids and surfactant compounded solutions

图5 四种液体润湿反转性能分析<br/>Fig.5 Performance of the four different liquids

图5 四种液体润湿反转性能分析
Fig.5 Performance of the four different liquids

图6 润湿反转模型<br/>Fig.6 Sketch map of wettability alteration

图6 润湿反转模型
Fig.6 Sketch map of wettability alteration

表2 润湿反转前后相关参数<br/>Table 2 Parameters used in the model

表2 润湿反转前后相关参数
Table 2 Parameters used in the model

图7 润湿反转前后相对渗透率变化<br/>Fig.7 Relative permeability before/after wettability alteration

图7 润湿反转前后相对渗透率变化
Fig.7 Relative permeability before/after wettability alteration

图8 润湿反转前后毛管压力变化<br/>Fig.8 Capillary pressure before/after wettability alteration

图8 润湿反转前后毛管压力变化
Fig.8 Capillary pressure before/after wettability alteration

图9 实验和模拟拟合图<br/>Fig.9 Data fitting of experiment and modeling

图9 实验和模拟拟合图
Fig.9 Data fitting of experiment and modeling

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备注

引言

1 致密岩心润湿反转实验

2 结果与讨论

3 润湿反转的模拟

4 现场应用

5 结论

期刊信息

备注