DOWNHOLE REFERENCING TECHNIQUES IN BOREHOLE SURVEYING

摘要

A method for determining rotational offset between first and second gravi ty 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.