Patching of injection and production well annular casing leaks for restoring mechanical integrity
US5954132A · kind A · utility
Inventors
Key dates
| Filing date | Nov 5, 1996 |
| Grant date | Sep 21, 1999 |
| Priority date | — |
| Expiry date | Nov 5, 2016 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B33/138
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A system designed to patch single and multiple casing leaks that occur in an injection well annulus where there is direct communication from the outermost casing string to the original open-hole wellbore and the adjacent earth strata. This system utilizes a four-stage process which consists of four separate types of fluids. The first injection stage is a CaCl.sub.2 solution in water. The second injection stage utilizes H.sub.2 SiO.sub.3, Na.sub.2 in a solution of water to create sodium metasilicate Na.sub.2 SiO.sub.3 in water. These two react in a double replacement chemical reaction to yield an aqueous phase and a solid phase. The third injection stage is then implemented, the same including a bentonite/attapulgite/diatomaceous earth slurry with large plugging materials suspended therein. The fourth stage utilizes covalently bonded N.sub.2 in a gaseous state. After injection of the first three stages N.sub.2 pressure is applied and the staged patching material migrates to the casing hole(s), thread leak, packer leak, or perforation. Upon restriction, the materials then combine and a filtration process beings. Filtration continues until the contents of the third stage have complete…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.