Extracting petroleum from underground beds contg. very salt water - by polymer flooding process, with pre-injection of part of the polymer soln. contg. a sacrificial substance and with reduced salinity

摘要

A polymer flooding process for extracting petroleum from oil-bearing underground deposits contg. highly saline retained water and/or flood water, which are drilled with both an injection borehole and a prodn. borehole in contact with the deposit, comprises injecting a sacrificial substance (I) in aq. soln. together with polymers dissolved in the underground water. The novelty is that a small part of the polymer flooding soln. (II), contg. substance (I), is mixed with fresh water or water of low salinity so as to lower its salt content to below the stability limit of (I), and the greater part of (II) is then injected at higher salinity, above the solubility limit of (I). USE/ADVANTAGE - The process enables the use of sacrificial substances, esp. modified or unmodified (i.e. inexpensive) lignosulphonates (LS), in the polymer flooding process, even in highly saline deposits. Thus, the LS can be added to the soln. of polymer (e.g. polyacrylamide - PAA) without difficulty.