06882937 is referenced by 30 patents and cites 45 patents.

A method for determining rotational offset between first and second gravity measurement devices deployed on a downhole tool is disclosed. The method includes positioning the tool in a previously surveyed section of a borehole that provides a historical survey including at least three previously surveyed azimuthal reference points and utilizing the gravity measurement devices to determine local azimuths at three or more sites in the previously surveyed section of the borehole. The method further includes comparing local azimuths with the historical survey and determining a rotational offset between the measurement devices that gives a best fit between local azimuths and the historical survey. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Title
Downhole referencing techniques in borehole surveying
Application Number
10/369353
Publication Number
6882937 (B2)
Application Date
February 18, 2003
Publication Date
April 19, 2005
Inventor
Graham McElhinney
Inverurie
GB
Assignee
PathFinder Energy Services
TX, US
IPC
G01V 011/00
View Original Source