RISER INSTALLATION FROM OFFSHORE FLOATING PRODUCTION UNIT.

摘要

A method for installing risers so they extend from a FPU (floating production unit) to multiple subsea hydrocarbon wells of an oil field, which avoids damage to the pipe sections and that is economical. As pipe sections are connected to a near end (56) of a pipe string portion (68B-68D) that lies at the FPU, a tug boat (30) pulls the far end (65) of the pipe string toward a well head. Initially, a long pull line (34) extends from a winch (32) on the tug boat, in a double catenary curve to the far end of the pipe string. The winch is operated to shorten the pull line until the pipe string extends in a double catenary curve (60). Tension in the pipe string is maintained at a proper level during installation by maintaining the near end portion of the pipe string so it extends at a near end angle (70) to the vertical that continually lies within a predetermined range, such as from 3?? to 12??.