Method for detecting formation resistivity outside of metal casing using time-domain electromagnetic pulse in well
US8756017B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 8, 2011 |
| Grant date | Jun 17, 2014 |
| Priority date | — |
| Expiry date | Oct 8, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for detecting formation resistivity outside of metal casing using time-domain electromagnetic pulse in a borehole, the method including steps of a) providing a borehole large power pulse transmitting source, recording an induced electromotive force ε, and full time digital recording a transmitted waveform and a received signal; b) conducting transmission-reception and superimposing received signals to improve signal to noise ratio; c) calculating corresponding casing response according to known casing parameters and recorded current waveform of the transmitting source to obtain a relative induced electromotive force Δεf; d) correcting relative induced electromotive force value; e) carrying out one-dimensional inversion and converting the observation signal into radial variation information of the formation resistivity; f) obtaining a two-dimensional image of the longitudinal and radial resistivity distribution of outer cased formation resistivity for measured well sections; and g) determining residual oil distribution in a reservoir from outer cased reservoir resistivity distribution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.