公开(公告)号：US11639639B2

公开(公告)日：2023-05-02

申请号：US16972569

申请日：2019-06-06

Applicant: MAERSK DRILLING A/S

Inventor： Jesper Holck ,  Kristian E. Hansen

IPC: E21B19/09 ,  B66C13/02 ,  E02D5/24 ,  B66D1/48 ,  B66D3/04 ,  E21B19/00

Abstract: A method for mitigating the effects of cable wear in an active heave compensated hoisting system of an offshore vessel in a locked to bottom mode of operation is disclosed. The method comprises supporting an upper end of a string which is connected to a subsea well from a travelling block of the hoisting system, wherein the travelling block is suspended from a crown block via a cable. The method further comprises operating an active heave compensation system to control a drawworks of the hoisting system to pay in and out the cable to compensate for motion of the offshore vessel and maintain a target overpull in the string. The method further comprises adjusting a ballast system of the offshore vessel to vary the draft of the vessel, and controlling the drawworks in accordance with the variation in the draft of the vessel to cause a length of cable to slip through the hoisting system and maintain the target overpull in the string.