Wellbore inertial directional surveying system

Patent · Tue Jan 29 04:00:00 EST 1991

OSTI ID:5495683

Andreas, R D; Heck, G M; Kohler, S M; Watts, A C

This patent describes a wellbore inertial directional surveying system for providing a complete directional survey of an oil or gas well borehole to determine the displacement in all three directions of the borehole path relative to the well head at the surface. The information generated by the present invention is especially useful when numerous wells are drilled to different geographical targets from a single off-shore platform. Accurate knowledge of the path of the borehole allows proper well spacing and provides assurance that target formations are reached. The tool is lowered down into a borehole on the electrical cable. A computer positioned on the surface communicates with the tool via the cable. The tool contains a sensor block which is supported on a single gimbal, the rotation axis of which is aligned with the cylinder axis of the tool and, correspondingly, the borehole. The gyroscope measurement of the sensor block rotation is used in a null-seeking servo loop which essentially prevents rotation of the sensor block about the gimbal axis. Angular rates of the sensor block about axes which are perpendicular to the gimbal axis are measured by gyroscopes in a manner similar to a strapped-down arrangement. Three accelerometers provide acceleration information as the tool is lowered within the borehole. The uphole computer derives position information based upon acceleration information and annular rate information. Kalman estimation techniques are used to compensate for system errors.

• Assignee: Dept. of Energy, Washington, DC (USA)
• Patent Number(s): A; US 4987684
• Application Number: PPN: US 7-415941
• OSTI ID: 5495683
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
03 NATURAL GAS
030300 -- Natural Gas-- Drilling
Production
& Processing
440700 -- Geophysical & Meteorological Instrumentation-- (1990-)
47 OTHER INSTRUMENTATION
ACCELEROMETERS
COMPUTERIZED CONTROL SYSTEMS
CONTROL SYSTEMS
DESIGN
DIRECTIONAL DRILLING
DRILLING
MEASURING INSTRUMENTS
MONITORING
MONITORS
NATURAL GAS WELLS
OFFSHORE DRILLING
OFFSHORE PLATFORMS
OIL WELLS
WELLS