Design Parameter Study of Heave Compensation System for Offshore Drilling Operations Considering Pneumatic and Hydraulic Control

Abstract

In this paper, design parameter study of heave compensation system of offshore drilling rig is discussed under the assumption of the drilling operations and considering the pneumatic and hydraulic control force exerted by the heave compensation system. The drilling operations were performed with a drilling rig composed of an offshore drilling system and a semi-submersible. Since the heave motion of the semi-submersible is caused by the ocean environment and affects the drilling operations, a heave compensation system is needed to control the position of the drill bit, so that it would remain stationary and unaffected by the heave motion. The heave compensation system is the boring tool used for drilling to control the position of the drill bit. It adopts the pneumatic and hydraulic control systems which are appropriate for transporting large amounts of work. At this juncture, pneumatic and hydraulic control refers to the manner of control accomplished by a pressurized fluid and operated by the fluid cylinder of the fluid motor. The fluid power is called hydraulics when the fluid is a liquid and is called pneumatics when the fluid is a gas. To carry out the dynamic response analysis of the heave compensation system, the equations of motion were constructed with a mass-spring-damper system. For the external forces exerted on the heave compensation system, the hydrostatic and hydrodynamic forces were considered to be acting on the hull of the semi-submersible rig. Also, for the control force of the heave compensation system, the pneumatic and hydraulic control systems were used, and the PD control algorithm was adopted. The dynamic response analysis of the heave compensation system was performed iteratively by inputting different values of the design parameters, after which the relationship between the design parameters and the heave compensation performance was analyzed. In addition, the strategy for the optimal design of the heave compensation system is discussed by setting up the space of the equipment and the operation cost and risk as objective functions of the design parameters.