Signal processing to enable utilization of a rig reference sensor with a drill bit seismic source
US5191557A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1991 |
| Grant date | Mar 2, 1993 |
| Priority date | — |
| Expiry date | Sep 13, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V2210/161
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus (10) for providing while drilling information on a subterranean geologic formation (28) includes a drilling rig (12) and a rotary drill bit (18) attached to the drilling rig (12) for providing seismic waves as it drills in the earth (16). Geophones (20) are spaced from the rotary drill bit (18) in the earth (16) and receive in direct seismic wave paths (26) and seismic wave paths (30) reflected from the subterranean geologic formation (28) the seismic waves provided by the drill bit (18). A reference sensor (24) is located on the drilling rig (12). The seismic signals sensed by the reference sensor (24) and by the geophones (20) are cross-correlated to separate the drill bit generated signals from interference signals by combining the reference signals and the signals received by the geophones (20). The cross-correlated reference signals and the signals received by the geophones (20) are separated into a first group of the drill bit generated seismic signals travelling to the geophones (20) in direct paths and a second group of the drill bit generated seismic signals travelling to the geophones (20) in paths reflected from the subterranean geologic formation (28). The …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.