APPARATUS AND METHOD FOR REMOVING ANISOTROPY EFFECT FROM DIRECTIONAL RESISTIVITY MEASUREMENTS

摘要

A directional resistivity tool includes at least one receiver deployed axially asymmetrically between at least one pair of transmitters. The transmitters are configured to transmit electromagnetic waves at first and second correspondingly distinct frequencies f 1 and f 2 such that: f 1 / f 2 = L 2 2 / L 1 2 , where L 1 and L 2 represent the corresponding axial distances between the first and second transmitters and the receiver. Exemplary embodiments of the invention further include a method for reducing the near-bed anisotropy effect. The anisotropy effect may be advantageously reduced (or removed) while at the same time providing for freedom in selecting the axial transmitter and receiver spacing.