Logging while drilling electrical imager and method for measurement in oil based mud

摘要

Method and apparatus for generating borehole imagery during logging while drilling by firing signals in the direction of a borehole formation. Using at least one transmitter T3-T4 in a horizontal array and/or at least one transmitter T1-T2 in a vertical array to fire signals into downhole formation. The fired signals engage the downhole formation, and at least one of receivers R3-R4 in a horizontal array and/or at least one of receivers R1-R2 in a vertical array receive respective horizontal and/or vertical reflected signals from the formation. The received signals are used to determine one or more vertical and/or horizontal formation parameters, generating an image. The apparatus comprises a cylindrical body with receivers which may be compactly disposed therein, enlarged apertures 410 for transmitters which are disposed around the receivers. The vertical and horizontal parameters may include one or more of the attenuation and phase difference of the formation and may include an omni-directional image.