聚乙烯醇胶乳油井水泥抗盐性能实验

Experiment of salt-resisting performance of polyvinyl alcohol latex oil-well cement

为了有效地使用聚乙烯醇胶乳油井水泥,采用氯化钠和氯化钙模拟现场水质和工况,应用API标准实验方法研究了其抗盐性能。研究结果表明,随着氯化钠或氯化钙加量的增大,水泥浆的失水量、初始稠度和游离水量逐渐增大,稠化时间逐渐缩短,水泥石的抗压强度和胶结强度略有增长。氯化钠和氯化钙的加量存在拐点值,该值随聚乙烯醇加量的增大而增大,超过该值后,水泥浆失水量急剧增大,当聚乙烯醇加量为0.1%,0.35%和0.7%时,氯化钠加量的拐点值分别约为1%,3%和4%,而氯化钙加量的拐点值则约为1.5%,2.5%和3%。机理分析结果表明,氯化钠和氯化钙主要是通过与聚乙烯醇反应以及介入水泥的水化进程影响水泥浆和水泥石的性能。

In order to effectively apply the polyvinyl alcohol latex oil-well cement, sodium- and calcium- chloride are both introduced to simulate the on-site water quality and operational situation, and the salt-resisting performance of the cement system is experimentally investigated by standard API test methods. The increasing concentration of the sodium- or calcium-chloride can result in the increment of fluid loss,initial consistency and free water content of cement slurry,the shortening of thickening time of the slurry, and a little improving of compressive strength and cementing strength of set cement. A breakpoint value is observed for the concentration of the sodium- and calcium- chloride. The value increases with the increasing of concentration of the polyvinyl alcohol , and the fluid loss of the cement slurry increases significantly as long as the value is surpassed. When the concentration of polyvinyl alcohol is 0.1% ,0. 35% and 0. 7% respectively in this experiment,the relevant breakpoint value of the concentration of sodium chloride is approximately 1% ,3% and 4% , and that of calcium chloride is about 1. 5% ,2. 5% and 3% respectively. Mechanism analysis demonstrates the main effect of the sodium-and calcium-chloride on the properties of the cement slurry and set cement is attributed to their reaction with polyvinyl alcohol as well as their participation in the cement hydration. The achievements obtained offer basic foundations for the development and application of the polyvinyl alcohol latex oil-well cement and other polyvinyl-alcohol-typed chemical auxiliaries in oil fields.