高温下PAM/PEI体系延缓成胶技术研究

Delayed Gelation of Polyacrylamide/Modified Polyethyleneimine Aqueous System at High Temperatures

使用一种氨基保护剂与3种商品聚乙烯亚胺反应,制得了钝化率不同(50%,70%,95%)的3个系列改性聚乙烯亚胺PEI-Sc,通过红外光谱和1H核磁共振谱确认了改性物的化学结构。考察了1.25%PAM(相对分子质量1.0×107)+0.625%PEI-Sc水溶液在120℃的成胶时间(形成Sydansk相对强度代码D级凝胶所需时间)。结果表明成胶时间随PEI-Sc钝化率的增大而大幅度增大,最大值超过40小时,为使用未改性PEI时的30倍以上;减小原料PEI的相对分子质量,增大配液用水的矿化度(由0增至6、20 g/L),均可增大成胶时间;在较低温度下(90℃,100℃),成胶时间大幅度增加。PEI-Sc/PAM体系可用于高温高盐油藏的堵水剂。

Three commercial grades of polyethyleneimine,PEI,of various molar mass were reacted with an amino functionalities protection agent to give three series of chemically modified PEI,notated as PEI-Sc,of deactivation degree 50%,70% and 95% and their chemical structures were identified by IR and 1H NMR techniques.For 1.25% polyacrylamide,PAM,＋0.625% PEI-Sc aqueous solutions,in which the PAM had molar mass of 1.0×107,the gelation time（GT）at 120℃ was investigated and determined as the time needed for the solutions to form an uneasily flowing gel of Sydansk＇s relative strength code D.It was shown that the GT was increased significantly with increasing the deactivation degree of PEI-Sc and the largest values of GT were more than 40 hrs,or more than 30 times of that when original PEIs were used;the GT was increased to some extent with increasing the molar mass of original PEIs or with decreasing the salinity of the gelling solutions（from 0 to 6 and 20 g/L）;at lower temperatures（at 100℃ and 90℃） the GT was increased dramatically.The PEI-Sc/PAM aqueous gelling systems suggested might be used for water shutoff/profile modification in high temperature and high salinity oil reservoirs.