Inhibition of scale from oil well brines utilizing a slow release composition and a preflush and/or after flush
US5604185A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 27, 1995 |
| Grant date | Feb 18, 1997 |
| Priority date | — |
| Expiry date | Mar 27, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09K8/528
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
An improvement in a method for the inhibition of scale deposition on the surfaces of a well coproducing oil and scale forming brines, said method comprising injecting into the well reservoir an acidic aqueous solution at a first pH containing dissolved therein a scale inhibitor, multivalent metal cations, 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. Such improvement comprises injecting as a preflush before said injection of inhibitor solution and/or as an afterflush after said injection of inhibitor solution, a solution of a heat sensitive pH-increasing substance and multivalent metal cations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.