Downhole fiber optic transmission for real-time well monitoring and downhole equipment actuation

A method of operating a well monitoring system, comprising:

• landing a tubing hanger in a wellhead, wherein the tubing hanger comprises a bore and a first fiber optic cable;
• landing a tree on the tubing hanger, wherein the tree comprises a bore and a second fiber optic cable, wherein a seal sub is coupled to the tree, wherein an upper end of the seal sub is disposed within an opening at a lower end of the tree, wherein the seal sub comprises a fiber optic communications line;
• and
• creating an electrical connection between the seal sub and the tubing hanger, wherein at least one of:
• the first fiber optic cable terminates at a first photodetector in the tubing hanger that is electrically coupled to the electrical connection and the fiber optic communications line terminates at a first optical transmitter in the seal sub that is electrically coupled to the electrical connection, or
• the first fiber optic cable terminates at a second optical transmitter in the tubing hanger that is electrically coupled to the electrical connection and the fiber optic communications line terminates at a second photodetector in the seal sub that is electrically coupled to the electrical connection.

A subsea wellhead system, comprising:

• a tubing hanger landed in a wellhead housing, wherein the tubing hanger comprises a bore and a first fiber optic cable;
• a tree landed on the tubing hanger, wherein the tree comprises a bore and a second fiber optic cable, wherein the second fiber optic cable extends from a surface location;
• a seal sub coupled to an inner wall of the tree, wherein the seal sub is landed in and engaged with an inner wall of the tubing hanger, wherein the seal sub comprises:
• a bore;
• and
• a fiber optic communications line that is communicatively coupled to both the first fiber optic cable and the second fiber optic cable;
• wherein the seal sub and the tubing hanger form an electrical connection regardless of an orientation of the tubing hanger relative to the tree;
• a transducer disposed at a downhole location about a tubing string suspended from the tubing hanger, wherein the first fiber optic cable is communicatively coupled to the transducer and extends between the transducer and the seal sub;
• a first photodetector disposed in the seal sub and communicatively coupled to the fiber optic communications line, the first photodetector configured to convert a light signal traveling through the second fiber optic cable from the surface location to an electrical signal communicated to the electrical connection;
• and
• a first optical transmitter disposed in the tubing hanger and communicatively coupled to the first fiber optic cable, the first optical transmitter configured to convert the electrical signal traveling through the electrical connection into a light signal communicated to the first fiber optic cable.