Surfactant oil recovery process usable in high temperature, high salinity formations

摘要

Many petroleum formations contain water having high salinity and/or high concentrations of divalent ions such as calcium or magnesium dissolved therein, and are additionally at temperature from about 70 DEG F. to about 300 DEG F. Most surfactants suitable for use in oil recovery operations are either ineffective in high salinity or high hardness waters, or cannot tolerate the higher temperatures encountered in many such formations. An aqueous fluid containing a water soluble alkylpolyalkoxyalkyl sulfonate or alkylarylpolyalkoxyalkyl sulfonate and a water-insoluble polyethoxylated aliphatic alcohol or polyethoxylated alkylphenol nonionic surfactant is effective in formations containing water whose salinity is from 70,000 to 220,000 parts per million total dissolved solids and also having temperatures as high as 300 DEG F. The fluid is phase stable over a wide range of formation temperatures and water salinities and hardness values.