Thickening brine with crosslinked carboxymethyl hydroxyethyl cellulose - useful as fluids in post primary oil recovery from wells (NO 7.3.77)

摘要

Thickened aq. brine is made contg. =0.025 wt. % carboxymethylhydroxyethylcellulose (CMHEC) with a carboxymethyl D.S. of 0.2-0.6 and a hydroxyethyl M.S. of 1.5-3.0, cross linked in soln. with a polyvalent metal cation added in the form of a salt in a ratio metal cation/COOH gp. of 0.025-1% molar, resp. 0.025-0.4% molar. The thickened aq. brines are esp. useful for recovering secondary amts. of oil from oil wells, in which a drive fluid is pumped into the well to force out additional amts. of oil. The thickener prevents 'fingering' of the fluid into permeable zones in the formation. The cross-linked CMHEC gives good thickening at low concn. is soluble in brine, and gives a fluid whose viscosity remains stable over long periods.