US Patent 7413018 Apparatus for wellbore communication

Methods and apparatus for communicating between surface equipment and downhole equipment. One embodiment of the invention provides a wellhead assembly that allows electrical power and signals to pass into and out of the well during drilling operations, without removing the valve structure above the wellhead. Another embodiment of the invention provides an electromagnetic casing antenna system for two-way communication with downhole tools. Another embodiment of the invention provides an antenna module for a resistivity sub that effectively controls and seals the primary/secondary interface gap.