Borehole electric field survey with improved discrimination of subsurface features
US9611736B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Aug 29, 2013 |
| Grant date | Apr 4, 2017 |
| Priority date | — |
| Expiry date | Jan 3, 2034 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A90/30
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Errors produced in a borehole to surface electromagnetic (BSEM) survey by near surface electrical anomalies on the estimates of formation properties are reduced. The effects of variations in subsurface electrical resistivity near the surface are separated from electrical resistivity changes at locations in the formations of interest far from the measurement region. A survey system includes one or more electrodes to inject electrical current at formation depth within a borehole, one or more counter electrodes which collect such current on the surface of the earth, and one or more electrodes to inject current on the surface. A transmitter is selectively connectable to different sets of the electrodes to cause a current to flow between the selected electrode sets. The resultant fields from the current flow are sensed and processed. The effects of near surface anomalies are detectable in the data and removable from the survey data of interest regarding the formations. The survey data more accurately indicates formation features or properties of interest.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.