单液法无机沉淀调剖体系的研制和性能评价

Research and Performance Evaluation of Inorganic Precipitation Profile Control System Injected in Single Slug

无机沉淀型调剖体系具有良好的溶解性和耐温耐盐性能,但存在反应物接触即沉淀的问题,施工方式多为双液法。为改善这一问题,以阻垢剂为缓沉剂,将其加入含碳酸钠和钙镁离子的水中制得可单液法注入的无机沉淀调剖体系。研究了缓沉剂浓度、水矿化度和钙镁离子浓度、温度对该调剖体系生成沉淀起始稀释倍数和稀释后沉淀量的影响,通过填砂管驱替实验考察了该调剖体系的注入性和封堵性。结果表明,缓沉剂的引入可以暂时抑制沉淀的产生以保证无机沉淀调剖体系能以单液法注入;当稀释至生成沉淀起始稀释倍数后缓沉剂将失去对沉淀的抑制作用,调剖体系重新产生沉淀以起到封堵作用。缓沉剂浓度越高,生成沉淀起始稀释倍数越大。增加水中钙镁离子浓度会降低生成沉淀起始稀释倍数,但可提高调剖体系的沉淀量。高温、高盐条件会降低生成沉淀起始稀释倍数,但沉淀量略有升高。组成为10%碳酸钠和2%缓沉剂聚天冬氨酸钠的调剖体系的注入性良好,对填砂管的封堵率约为70%。该无机沉淀调剖体系可用淡水、地层水、海水配注,适用于干旱缺水、海上平台等缺少淡水资源的特殊环境。

Inorganic precipitation profile control system had good solubility,temperature and salinity tolerant,and usually used in double fluid injection process because of the precipitation reaction between different reactants. In order to improve this problem,by using scale inhibitor as precipitation inhibitor and using sodium carbonate and mineralized water with calcium and magnesium ions as reactants,inorganic precipitation profile control system which could be injected in single slug was obtained. The effects of precipitation inhibitor concentration,water salinity,calcium and magnesium ions concentration,temperature on the initial dilution ratio of precipitate formation and precipitation weight were investigated. The injection and plugging properties of the profile control system were also investigated by sand pack displacement experiment. The experimental results showed that,precipitation inhibitor could temporarily inhibit the formation of precipitation to ensure that profile control system could be injected in single slug. Precipitation inhibitor would lose its effect when dilution ratio was more than initial dilution ratio of precipitate formation,and the profile control system would reproduce precipitation to block. With increasing concentration of precipitation inhibitor,the dilution ratio increased. With the increase of calcium and magnesium concentration in mineralized water,the dilution ratio decreased but precipitation weight increased. The dilution ratio decreased under high temperature and high salinity environment,but precipitation weight increased slightly. The profile control system had good injectivity at the same time. Its plugging ratio could reach 70% for the profile control system consisting of 10% Na2CO3 and 2% sodium of polyaspartic acid. The profile control system could be prepared by fresh water,formation water or even seawater,and was suitable for special environments such as drought and lack of freshwater resources,offshore platforms and so on.