Study On The Properties Of Soluble Silicate As Plugging Agent

Due to its advantages of low cost, temperature tolerance, salt resistance, good injectivity, friendly environment and suitability to harsh reservoir conditions, soluble silicate is applied widely for profile control and water plugging in oilfield. Sodium silicate is the most representative soluble silicate, for which the study on sodium silicate is greatly important to guide the application of soluble silicate for profile control and water plugging in oilfield.The properties of sodium silicate as plugging agent are studied in the paper, including the sensitivity to calcium or magnesium which means reacting with calcium or magnesium ion even low concentration to pruduce deposits, the sensitivity to salt which means with hypersalinity saline water forming gel or deposit, the sensitivity to temperature which means generating deposits with high temperature and the sensitivity to acid which means bringing about gel under the effect of acidic activator. The results indicate that the sensitivity to calcium or magnesium is affected slightly by temperature, the sensitivity to salt is influenced greatly by salinity, while slightly by temperature, the sensitivity to temperature is affected dramatically by temperature, sodium silicate concentration and time, and the sensitivity to acid is influenced obviously by inorganic salt, temperature and pH value.Except study on the properties and influential factors of sodium silicate, a series of sodium silicate multisystems is studied with sodium silicate as the major agent. Among the sodium silicate multisystems, the sodium silicate and urea system forms gel under high temperature (80℃~130℃) with the advantages of easy preparation, high temperature tolerance and excellent stability, and the sodium and HPAM system forms gel affected by activator and presents perfect viscoelasticity and fine stability under low temperature(30℃~70℃).