Early evaluation by fall-off testing
US5555945A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1994 |
| Grant date | Sep 17, 1996 |
| Priority date | — |
| Expiry date | Aug 15, 2014 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B49/008
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Early evaluation testing of a subsurface formation is provided by monitoring pressure fall-off in the formation. This is accomplished by providing a column of fluid in the well having an overbalanced, hydrostatic pressure at the subsurface formation greater than a natural formation pressure of the subsurface formation. A testing string is run into the well, and the testing string includes a packer, a pressure monitor and a closure tool arranged to close a bore of the testing string. The formation is shut in by setting the packer and closing the bore of the testing string with the closure tool and thereby initially trapping the overbalanced hydrostatic pressure of the column of fluid in the well below the packer. Then the pressure in the well below the packer is monitored as it falls off toward the natural formation pressure. This data can be extrapolated to estimate the natural formation pressure based upon a relatively short actual test interval on the order of ten to fifteen minutes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.