Reducing error contributions to gyroscopic measurements from a wellbore survey system

摘要

A method reduces error contributions to gyroscopic measurements from a wellbore survey system having two gyroscopic sensors adapted to generate signals indicative of at least one component of the Earth's rotation substantially perpendicular to the wellbore (20) and indicative of a component of the Earth's rotation substantially parallel to the wellbore. The method includes generating a first signal indicative of the at least one substantially perpendicular component while the first sensor (12) is in a first orientation; generating a second signal indicative of the at least one substantially perpendicular component while the first sensor (12) is in a second orientation; generating a third signal indicative of the substantially parallel component while the second sensor (14) is in a first orientation; and generating a fourth signal indicative of the substantialy parallel component while the second sensor (14) is in a second orientation. The method further includes calculating information regarding at least one of a mass unbalance offset error and a quadrature bias error using the first, second, third, and fourth signals.