초록 ▼

A method for the inhibition of scale deposition on the surfaces of a well coproducing oil and scale forming brines comprising injecting into the well reservoir an acidic aqueous solution at a first pH containing dissolved therein a scale inhibitor, multivalent metal ions, and a heat sensitive pH inc

A method for the inhibition of scale deposition on the surfaces of a well coproducing oil and scale forming brines comprising injecting into the well reservoir an acidic aqueous solution at a first pH containing dissolved therein a scale inhibitor, multivalent metal ions, and a heat sensitive pH increasing substance which decomposes at elevated temperatures liberating an alkaline compound such that the solution is inherently heated by the higher ambient reservoir temperature to a temperature at which the alkaline compound is liberated from the heat sensitive substance thus raising the pH of the solution to a point at which a sparingly soluble multivalent metal salt of the scale inhibitor is phase separated from the solution on the porous surfaces of the reservoir rock formation, providing for a slow release of inhibitor into the produced brines when the well is in its production phase.

대표청구항 ▼

A method for the inhibition of scale deposition on the surfaces of a well coproducing oil and scale forming brines comprising injecting into the well reservoir an acidic (aqueous) solution at a first PH containing dissolved therein a scale inhibitor, multivalent metal ions in the presence of which s

A method for the inhibition of scale deposition on the surfaces of a well coproducing oil and scale forming brines comprising injecting into the well reservoir an acidic (aqueous) solution at a first PH containing dissolved therein a scale inhibitor, multivalent metal ions in the presence of which said scale inhibitor is soluble at said first pH but with which it forms sparingly soluble salts at a higher pH, and a heat sensitive pH increasing substance which decomposes at elevated temperatures liberating an alkaline compound such that the solution is inherently heated by the higher ambient reservoir temperature to a temperature at which the alkaline compound is liberated from the heat sensitive substance thus raising the pH of the solution to said higher pH at which a sparingly soluble multivalent metal salt of the scale inhibitor is phase separated from the solution on the porous surfaces of the reservoir rock formation, providing for a slow release of inhibitor into the produced brines when the well is in its production phase, said heat sensitive pH increasing substance being 1) urea or a urea derivative which has the formula R1R2NCONR3R4 where the R\s are the same or different and each is hydrogen or an alkyl group containing 1 or 2 carbon atoms, or is 1-phenylurea, 1-methyl-3-phenylurea or 1-ethyl-1phenylurea; 2) an acyl azide which on being heated to above about 80°C. rearranges to the corresponding isocyanate with the liberation of nitrogen; or 3) cyanic acid.