Measurement-while-drilling assembly using gyroscopic devices and methods of bias removal
US6347282B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 1998 |
| Grant date | Feb 12, 2002 |
| Priority date | — |
| Expiry date | Dec 16, 2018 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/022
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
This invention provides a measurement-while-drilling (MWD) downhole assembly for use in drilling boreholes which utilizes gyroscopes, magnetometers and accelerometers for determining the borehole inclination and azimuth during the drilling of the borehole. The downhole assembly includes at least one gyroscope that is rotatably mounted in a tool housing to provide signals relating to the earth's rotation. A device in the tool can rotate the gyroscope and other sensors on the tool at any desired degree. A processor in the tool combines measurements from the sensors taken at a plurality of positions at the same depth to determine the systematic bias in the sensors before further processing. Accelerometers in the MWD tool provide gravity measurements from which the toolface and inclination are determined. The unbiased gyroscopic measurements are used in conjunction with the tool face and inclination measurements to determine the azimuth and tool face with respect to true north. Three axially spaced apart magnetometers may be used to correct for local magnetic disturbances. Additionally, when measurements are made with magnetic, accelerometer and gyroscopic measurements along three diff…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.