METHOD AND SYSTEM FOR DETERMINING FORMATION ANISOTROPIC RESISTIVITY WITH REDUCED BOREHOLE EFFECTS FROM TILTED OR TRANSVERSE MAGNETIC DIPOLES

摘要

Systems and methods are provided for determining subsurface formation properties using an antenna system disposed within a borehole traversing the formation. A loggin g system includes a well tool implemented with an antenna system having transverse or tilted magnetic dipoles. One antenna implementation uses a set of three coils having non- parallel axes. Through mechanical or electromagnetic rotation of an antenna about its axis in order to maximize or minimize couplings, the systems and methods are used to estimate formation anisotropic resistivity, providing reduced borehole effects in vertical and small deviation wells. This invention may also be applied in deviated wells when the borehol e is perpendicular to the strike direction, as is often the case in wireline logging.