Electrical imaging in conductive and non-conductive mud

Abstract

The invention is a method and apparatus for determining an electrical property a formation surrounding a borehole with a measuring-while-drilling device. The apparatus an antenna configuration disposed along the outer face of an extendable stabilizer joined to a rotatable drill collar. Typically, two receivers and two transmitters are spaced along the longitudinal axis of the drill collar, with the two receivers spaced symmetrically in between the two transmitters. Alternatively, receivers and transmitters can be spaced along the circumference, possibly over multiple stabilizers. Multiple assemblies can be used. Data can be obtained with the transmitter-receiver assembly held in a stationary position or rotating circumferentially. Apparatus can be operated in a “broadside” configuration, an “endfire” configuration, or a configuration in which transmitter coils and receiver coils are oriented orthogonally to each other.

Dependencies are inferred from the claim text.