Method of increasing retention of scale inhibitor in subterranean formations
US4947934A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 2, 1989 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Feb 2, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S507/927
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A method for inhibiting the formation of scale in a well penetrating a subterranean formation for the production of fluids from the formation comprising injecting into the formation an acidic aqueous solution having a pH effective to form a water-soluble complex of the inhibitor and the polyvalent cation, preferably in the range of 2 to 3, containing a mixture of a polyacrylate scale inhibitor having a molecular weight range from 500 to 10,000 and a polyvalent cation wherein the equivalent ratio of polyvalent cation to polyacrylate scale inhibitor is less than or equal to 0.5 in the acidic aqueous solution and allowing natural conditions in the formation to raise the pH of the solution an amount sufficient to cause controlled precipitation and increased deposition of the scale inhibitor in situ in the form of the polyvalent cation-polyacrylate complex. The scale inhibitor solution employed in this method avoids premature plugging of the formation, substantially extends the lift of the treatment and the polyvalent cation complex of the polyacrylate is fully inhibitive.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.