Methods and apparatus for making directional measurements of earth formatio ns surrounding a borehole. New antenna coil shield designs are utilized to provide selective attenuation of at least one electromagnetic energy field component as the component interacts with the shield. The new shields are implemented in several downho le tool configurations to provide azimuthally focused formation measurements. In effect, the new shield filters interacting electromagnetic energy field components to pa ss those components corresponding to a magnetic dipole oriented at an angle from the tool axis. The shields thereby alter a coil's envelope of influence to electromagnetic energy. The new shields also form part of a system for making directional measurements while drilling.
申请公布号
CA2327157(A1)
申请公布日期
2001.06.01
申请号
CA20002327157
申请日期
2000.11.30
申请人
SCHLUMBERGER CANADA LIMITED
发明人
CLARK, BRIAN;BONNER, STEPHEN D.;OMERAGIC, DZEVAT;HOMAN, DEAN M.;ROSTHAL, RICHARD A.;BARBER, THOMAS D.;CHESSER, SCOTT S.