Wellhead with improved ESP cable pack-off and method

A wellhead 10 for use with subterranean wells includes an improved tubing hanger 16 including an improved electric power cable pack-off port 20 that permits positioning an electric submersible pump ("ESP") power cable 40 through the port 20 in the tubing hanger. The improved wellhead permits installation of packing 34 and compression rings 30, 32 within the power cable port 20 to create a vapor-tight pressure seal around the outer cable jacket 41 . The seal may be rated at pressures of at least 750 psia. The wellhead 10 comprises a wellhead body 12 for supporting a tubing hanger 16, the tubing hanger including a tubing port 22 and a power cable port 20 for passing electrical power from an electrical power source 72 through the power cable port to the electric motor M. The wellhead 10 also includes a cable seal 34 within the power cable port, a lower packing seat 66, and a packing gland 24 selectively moveable with respect to the seat for compressing the cable seal 34 to form a pneumatic seal.