Encapsulated water absorbent polymers as lost circulation additives for aqueous drilling fluids
US4664816A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 28, 1985 |
| Grant date | May 12, 1987 |
| Priority date | — |
| Expiry date | May 28, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S507/902
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
The disclosed invention is a novel drilling fluid additive for use in reducing lost circulation in wellbores and a method for employing the invention additive for reducing such lost circulation. The invention additive is a highly water absorbent polymer encapsulated by a reaction-preventive protective casing to prevent the polymer from expanding by absorbing water until it is desired to breach the casing. The reaction-preventive protective casing may be a film which will dissolve after a desired time of residence in the borehole or a film or waxy substance which will dissolve or melt at a desired temperature in the borehole, releasing the water absorbent polymer to expand by absorbing water. The substantially expanded polymer will seal off thief zones and fissures, reducing lost circulation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.