Wellbore inertial directional surveying system

Patent · Tue Jan 01 00:00:00 EST 1991

OSTI ID:867684

Andreas, Ronald D ^[1]; Heck, G Michael ^[1]; Kohler, Stewart M ^[1]; Watts, Alfred C ^[1]

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1. Albuquerque, NM

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 aboutthe 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 anular rate information. Kalman estimation techniques are used to compensate for system errors.

• Research Organization: AT&T
• DOE Contract Number: AC04-76DP00789
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4987684
• OSTI ID: 867684
• Country of Publication: United States
• Language: English

Related Subjects

wellbore
inertial
directional
surveying
providing
complete
survey
oil
gas
borehole
determine
displacement
directions
path
relative
head
surface
information
generated
especially
useful
numerous
drilled
geographical
targets
single
off-shore
platform
accurate
knowledge
allows
proper
spacing
provides
assurance
target
formations
reached
tool
lowered
electrical
cable
computer
positioned
communicates
via
contains
sensor
block
supported
gimbal
rotation
axis
aligned
cylinder
correspondingly
gyroscope
measurement
null-seeking
servo
loop
essentially
prevents
aboutthe
angular
rates
axes
perpendicular
measured
gyroscopes
manner
similar
strapped-down
arrangement
accelerometers
provide
acceleration
uphole
derives
position
based
anular
rate
kalman
estimation
techniques
compensate
errors
sensor block
position information
especially useful
rotation axis
electrical cable
rate information
manner similar
path relative
target formation
wellbore inertial
inertial directional
directional surveying
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