二氧化碳增稠剂的制备及其压裂性能评价

发布时间：2018-05-14 23:18

  本文选题：非常规油气资源 + 二氧化碳　； 参考：《西南石油大学》2017年硕士论文

【摘要】：针对非常规油气储层的压裂改造,在大量调研了国内外关于CO_2压裂液增稠剂的研究现状后,设计合成了一类含氟的增稠剂,用来增稠CO_2,并制备成压裂液体系。本文以全氟辛酸、丝氨醇、乙醇胺、1,6-己二异氰酸酯以及二碳酸二叔丁酯作为反应原料经氨基保护、酯化反应、脱保护和亲核加成反应分别得到C02增稠剂SCT、DCT。首先,对丝氨醇、乙醇胺中的氨基上保护基团,起到保护氨基的作用。然后,通过酯化作用,将已从全氟辛酸制备成的全氟辛酰氯引入到N-Boc-丝氨醇和羟乙基氨甲酸叔丁酯中。最后,脱氨基保护后,将产物与1,6-己二异氰酸酯反应得到单链、双链增稠剂。其中,采用单因素法优化了合成N-Boc-丝氨醇和羟乙基氨甲酸叔丁酯中的投料比,通过正交试验对酯化反应过程中反应温度、时间以及投料比进行了优化,确定了最佳合成条件。通过FTIR、13C-NMR对中间产物和最终产物进行了结构表征。深入研究增稠剂的热性能和在CO_2、凝析油、去离子水中的溶解性能。结果表明:增稠剂DCT、SCT的热稳定性能好,分别在200℃和170℃才发生热降解,满足了现有页岩气储层温度的需要;通过静态法研究了两种增稠剂在CO_2中的溶解性能,利用Chrastil半经验模型对实验溶解度进行线性关联,单链、双链增稠剂的实验值与理论值的平均相对偏差分别为11.14%和9.52%,线性拟合程度较高,关联性好,表明实验测量值较为准确;此外,在40℃、60℃和80℃的不同温度条件下,两种增稠剂都难溶于凝析油和水中,有利于压裂后返排和后续的地面处理。考察了合成得到的增稠剂在CO_2中的增稠效果以及对岩心的伤害率。通过单因素法,对增稠剂的加入量进行了筛选,结果表明,增稠剂DCT和增稠剂SCT的最佳加入量为2wt%,其将C02的粘度从0.04mPa·s分别提升至1.54mPa·s和1.46mPa.s,增加幅度分别约为39倍和36倍。随着温度上升,混合体系的粘度下降,在温度从30℃升至40℃时,粘度出现上升,后继续下降;而体系的粘度随着压力值的上升而上升;随着剪切速率的上升,体系的粘度也随之下降,属于一类典型的剪切变稀的假塑性流体;增稠剂DCT和增稠剂SCT对岩心的伤害率都较低,分别为1.43%和1.62%,均远远小于常规的水基压裂液,能够满足"石油与天然气行业标准SY/T 6367-2008压裂液通用技术条件"的要求。
[Abstract]:In view of fracturing modification of unconventional oil and gas reservoir, a kind of fluorine-containing thickener was designed and synthesized after a large number of researches on thickening agent of CO_2 fracturing fluid at home and abroad, which was used to thicken CO-2 and to form fracturing fluid system. In this paper, perfluorooctanoic acid, sericin, ethanolamine 1-hexadiisocyanate and di-tert-butyl dicarbonate were used as raw materials to obtain C02 thickener SCT _ (DCT) by amino protection, esterification, deprotection and nucleophilic addition respectively. First, protect the amino groups from the amino groups in sericin, ethanolamine, and play the role of protecting amino groups. Then, the perfluorooctanoyl chloride which had been prepared from perfluorooctanoic acid was introduced into N-Boc-serine and hydroxyethyl carbamate tert-butyl ester by esterification. Finally, after deamination protection, the product was reacted with 1% hexane diisocyanate to form a single chain and double chain thickener. Single factor method was used to optimize the feed ratio of N-Boc-serine and hydroxyethyl carbamate tert-butyl ester. The reaction temperature, time and feed ratio were optimized by orthogonal test, and the optimum synthesis conditions were determined. The intermediate and final products were characterized by FTIR 13C-NMR. The thermal properties of thickener and its solubility in CO2, condensate and deionized water were studied. The results show that the thermal stability of thickener DCT / SCT is good, and thermal degradation occurs at 200 鈩，

本文编号：1889920