Method and apparatus for borehole directional logging

Abstract

Abstract A METHOD AND APPARATUS FOR BOREHOLE DIRECTIONAL LOGGING. THE APPARATUS INCLUDES A FIRST COIL ADAPTED FOR ROTATION ABOUT AN AXIS ALIGNED WITH THE LONGITUDINAL AXIS OF THE BOREHOLE AND A GIMBAL MOUNTED MAGNETIC FIELD PRODUCING COIL FOR GENERATING A FIRST MAGNETIC FIELD OF PREDETERMINED DIRECTION WITH RESPECT TO THE VERTICAL IN THE SPACE OCCUPIED BY THE FIRST COIL WHEREBY AN ALTERNATING SIGNAL IS INDUCED THEREIN REPRESENTATIVE OF THE INCLINATION ANGLE OF THE BOREHOLE. A SECOND COIL IS PROVIDED FOR ROTATION AT THE SAME RATE AS THE FIRST COIL WHILE BEING SUBJECTED TO A SECOND MAGNETIC FIELD HAVING AT LEAST A COMPONENT OF KNOWN AZIUM DIRECTION, THEREBY GENERATING AN ALTERNATING SIGNAL IN THE SECOND COIL, THE PHASE ANGLE OF WHICH, WITH RESPECT TO THE FIRST COIL SIGNAL IS RESPECTIVE OF THE AZIUM ANGLE OF THE BOREHOLE. COMPUTING APPARATUS IS SHOWN FOR DETERMINING THE LOCATION OF A SELECTED SEGMENT OF THE BOREHOLE AT ANY DEPTH INCLUDING MATHEMATICAL AND TRIGONOMETRIC FUNCTION OPERATORS FOR GENERATING SIGNALS REPRESENTATIVE OF THE INCREMENTAL CHANGES OF THE BOREHOLE POSITION AND OF THE CORRESPONDING INCREMENTAL LENGTH SEGMENTS ALONG THE BOREHOLE. ALSO INCLUDED ARE COMPUTING ELEMENTS FOR SUMMING THE LATTER SIGNALS THEREBY OBTAINING THE LOCATION OF THE BOREHOLE AT ANY DEPTH. THE METHOD INCLUDES GENERATING FIRST AND SECOND SIGNALS RESPECTIVE OF THE BOREHOLE INCLINATION AND AZIMUTH, RESPECTIVELY, AND IN RESPONSE THERETO GENERATING SIGNALS OF THE INCREMENTAL CHANGES IN THE LOCATION OF SUCCESSIVE SEGMENTS OF THE BOREHOLE CORRELATED WITH A SIGNAL REPRESENTATIVE OF THE LENGTH OF SAID SEGMENTS, AND GENERATING SIGNALS REPRESENTATIVE OF THE BOREHOLE LOCATION ALONG ITS LENGTH BY SUMMING THE LATTER SIGNALS.

Inventors

• 👤 Fontaine C Armistead

Bibliographic Details