Patent ID: 7918271
Filing Date: 2011-04-05
Classification: E21B

Abstract:
1. A wellhead assembly for providing a power connection to a downhole electrical device, comprising: one or more pressure-containing wellhead body members supported above a surface casing, the one or more wellhead body members forming and enclosing a vertical wellbore which extends through the one or more wellhead body members; an isolated tubing hanger supported by the one or more wellhead body members within the vertical wellbore, the isolated tubing hanger suspending therefrom a conducting tubing string; a grounding tubing hanger supported by the one or more wellhead body members within the vertical wellbore, the grounding tubing hanger suspending therefrom a grounding tubing string concentrically spaced from the conducting tubing string; the conducting tubing string and the grounding tubing string each being electrically conductive and extending downhole spaced from the surface casing in electrical connection with the downhole electrical device; the isolated tubing hanger and the grounding tubing hanger each being supported in sealed relationship within the vertical wellbore; the isolated tubing hanger having an outer housing which seats in the vertical wellbore of one of the one or more wellhead body members, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection to, and suspend, the conducting tubing string, and insulation between the outer housing and the conducting portion to electrically isolate the outer housing from the conducting portion; a hot electrical connection for making an electrical connection to the conducting tubing string or to the conducting portion of the isolated tubing hanger; electrical isolation associated with the hot electrical connection and the one or more wellhead body members for sealing and electrically isolating the hot electrical connection such that the one or more wellhead body members remain electrically isolated from the hot electrical connection; a grounding connection connected to the one or more wellhead body members for making a ground connection to the grounding tubing string; and a source of current having a first connection to the hot electrical connection and a second connection to the grounding connection.