摘要
开发易注入、可形成有效封堵的裂缝封窜技术,对于二氧化碳驱提高采收率技术具有重要意义。本文对硅酸乙酯进行改性提高其耐温性和不溶性,再乳化形成易注入的O/W乳液。考察了乳化剂类型和乳化剂用量对胶凝过程的影响。明确了pH值、温度和矿化度等因素对凝胶性能的影响,并通过人造岩心评价了该硅酸凝胶体系的封堵性能。结果表明,20%Span-80+80%Tween-80组成的复合乳化剂乳化效果最好,当乳化用量为1%时,乳化稳定性最好,粒径均一,易注入。当环境pH小于7时,可诱导乳液形成凝胶;随着温度的升高,成胶强度增强,但在150℃高温下,成胶强度下降。升高矿化度可加速凝胶的生成,但对凝胶强度影响较小。动力学分析表明,H+浓度是影响凝胶产生的关键因素,因此可在CO_(2)驱替酸性环境中,实现地层封堵。岩心实验结果显示,该凝胶颗粒可显著降低地层渗透率,封堵效果大于80%,可满足二氧化碳驱防气窜要求。
It is of great significance to develop the anti-channeling chemical formulation which can form effective plugging during carbon dioxide flooding.In this work,chemical modification was performed on ethyl silicate to improve its thermal stability and insolubility.The product was then emulsified into O/W emulsion which was readily to inject.The effects of emulsifier and its dosage on gelation were investigated.The influences of pH value,temperature and salinity on the gel properties were examined.The plugging performance of the silicic acid gel system was evaluated through artificial core flooding test.The results show that the emulsifier composed of 20%Span-80+80%Tween-80 possesses the best emulsifying performance.When the emulsifying dosage is 1%,the particle size was uniform,both the emulsion stability and the injectability are the best.When the pH value is lower than 7,the emulsion can form gel.With the increase of temperature,the gel strength increases,but at the high temperature of 150℃,the gel strength decreases.The salinity can accelerate the formation of gel,but has little effect on the gel strength.Kinetic analysis shows that H~+concentration is the key factor determining gel formation,which can achieve formation plugging ing the acid environment of CO_(2)flooding.In the core test,the gel particles can significantly reduce the formation permeability,and the sealing effect is greater than 80%,showing promising potential for practical uses.
作者
刘笑春
鄢长灏
何治武
付继有
王晨
LIU Xiao-chun;YAN Chang-hao;HE Zhi-wu;FU Ji-you;WANG Chen(Oil and Gas Technology Research Institute,Changqing Oilfield Branch Company,PetroChina,Xi'an 710018,China;Shale Oil Development Branch Company,Changqing Oilfield Branch Company,PetroChina,Qingyang 745100,China;Key Laboratory of Light Chemical Additives Chemistry and Technology,Ministry of Education,Shaanxi University of Science and Technology,Xi'an 710021,China)
出处
《化学研究与应用》
CAS
北大核心
2024年第8期1922-1928,共7页
Chemical Research and Application
基金
中国石油集团(股份)公司科技重大专项“长庆黄3区二氧化碳驱先导试验”(2022ZS0803)资助。
关键词
CO_(2)驱
防气窜
乳化
硅酸
CO_(2) flooding
anti-channeling
emulsify
silicic acid
