Well logging apparatus and method for determining properties of earth formations that have been invaded by borehole fluid
US5963036A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 1997 |
| Grant date | Oct 5, 1999 |
| Priority date | — |
| Expiry date | May 14, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/30
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus is disclosed for determining the properties of formations surrounding an earth borehole that have been invaded by borehole fluid to form an invaded zone. Properties determined in one embodiment are invaded zone resistivity Rxo, diameter of invasion DI, and uninvaded formation resistivity Rt, and the following steps are performed: (a) suspending a logging device in the borehole; (b) transmitting electromagnetic energy from a transmitter location on the logging device, and receiving the transmitted electromagnetic energy at receiver locations on the logging device for a first transmitter-to-receivers spacing associated with the transmitter and receiver locations; (c) determining, from the received electromagnetic energy, measurement characteristics associated with the first transmitter-to-receivers spacing; (d) repeating steps (b) and (c) for a plurality of further transmitter-to-receivers spacings to obtain measurement characteristics for the plurality of further transmitter-to-receivers spacings; (e) generating a model of formation of resistivity Rt with an invaded zone of resistivity Rxo and diameter of invasion DI; (f) selecting values of Rxo, DI, and Rt th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.