聚丙烯酰胺凝胶堵水剂及延迟交联机理研究

PAM/PHPAM GELLING FLUIDS FOR WATER PLUGGING AND DELAYED CROSS-LINKING MECHANIZMS OF PAM/PHPAM

本文介绍了能适应灰、砂岩孔、缝型油藏并可延迟交联的PAM凝胶堵水剂体系。其特点是:①应用有机多元延迟交联剂与化学反应平衡原理,较好地解决了交联几率与交联度的相互矛盾问题;②利用一剂多效应与氧化-还原反应原理,有效地解决了体系内自生酸调pH值和热稳定性的方法与技术难题;③运用优选法筛选出了一套不用铬离子的PAM凝胶堵水剂与延迟交联的配方。通过灰岩封堵模拟试验、脱水凝胶的红外光谱和电镜扫描检验,该堵剂的堵效、强度和封堵周期都是令人满意的。

Several formulations are selected from three basic systems with a bicomponent organic cross-linking agent, i. e. urotropine+formaldehyde, which might lead to controllable delayed cross-linking of aqueous PAM/PHPAM solutions with fonnation of optimum hydrogels for water plugging.These systems are (1) polymer+urotropine+ethylenediamine;(2) polymer+urotropine+formaldehyde+K_2S_2O_8;(3) polymer+urotropine+formaldehyde+ NH_4Cl. It is shown that only the formulations of systems (2) and (3) have successfully gone through the laboratory simultating tests on water plugging in limestone and sandstone reservoir,Single urotropine or formaldehyde can not serve a satisfactory cross-linking agent for controllable delayed aqueous PAM/PHPAM systems. The effects of concentrations of components and pH of media on cross-linking/gelation processes and properties oi gelled systems are studied,The mechanizms of cross-linking with urotropine+formaldehyde in the presence of K_2S_3O_8 or NH_4Cl are discussed.