Portable drillstring compensator

Offshore staff

U.S. patent number US7131496
Appl. Data: 11 20050715
Applicant: Control Flow Inc.
Inventor(s): Williams, Richard D. Coffey, Lacey C.

A closed system drill string compensator having a hydraulic fluid accumulator, at least one air pressure vessel, and a piston and a piston rod slidably engaged within a cylinder. The drill string compensator provides tensioning force for supporting a drillstring and permits the drilling vessel to remain connected to the drillstring during ocean level changes caused by wave action or ocean heave. In one embodiment, the accumulator surrounds the cylinder and at least one air pressure vessel is disposed radially around the accumulator and the cylinder. In another embodiment, the accumulator surrounds the cylinder and includes two ports, one port for permitting fluid communication between the cylinder and the accumulator and a second port for permitting fluid communication between the accumulator and the air pressure vessel, the first port including a shut-off valve. Methods of compensating a drill string also are disclosed.

11/21/2006