Active positioning of downhole devices using spherical motors

Apparatus and method for controlling northerly turning error in

Apparatus and method for measuring curvature of tubes

Azimuth determination for vector sensor tools

Azimuth determination for vector sensor tools

Bend detector pig

Borehole drift-direction probe

Borehole tool

Directional drilling of bore holes

Downhole tool

Error reduction in compensation of drill string interference for

Gyroscopic instrument

Heading indicator and method of using

High speed well surveying and land navigation

Mapping apparatus employing two input axis gyroscopic means

Measuring device for measuring deviation of body and method...

Measuring instruments

Method and apparatus for use in creating a magnetic...

Method for connecting magnetic measurements performed in a well

Method for determining azimuthal direction relative to true nort