Active Heave Compensation System Research Articles

Modelling and simulation of a hydraulic active heave compensation system

The following work presents modelling, simulation and results of hydraulic motor and hydraulic cylinder position measurement for a hydraulic active heave compensation system (AHC). In order to perform experimental research the authors developed a test stand. A hydraulic cylinder is used to carry out a simulation of sea waves. The development of a test stand made it possible to compare the simulation with the experimental results. A hydraulic motor is used for compensation of sea waves. Optimization of design parameters for such systems can be done by analysing a model simulation. The main components of this system were modelled. This model was implemented in simulation software Mathlab Simulink and its dynamic performance was tested. The Authors presented the simulation and the experimental results for main components of a hydraulic active heave compensation system.

Control Characteristics of Secondary Regulated Active Heave Compensation System

Control Characteristics of Secondary Regulated Active Heave Compensation System

Dynamics analysis and active control of a floating crane

Original scientific paper The floating cranes, which transfer payloads during offshore constructions, need meet rigorous demands for efficiency and safety in serious sea conditions while the unexpected motion of the floating crane caused by wave make it even harder. This paper analyses the dynamics of a floating crane and presents an active heave compensation system (HCS) to allow the payloads motion decoupled from the wave-induced ship motion in the vertical direction. Specifically, virtual prototyping technology is introduced for the floating crane systems to investigate the real behaviour of the HCS. A virtual mechanical model of the floating crane is created to analyse the dynamics of the floating crane. In addition, an active HCS is designed for the under actuated floating crane system. A self-adaptive PID control law based on improved genetic algorithm is proposed for the essential part of the HCS. The co-simulation and experiment results demonstrate that the payload motion due to the ship’s vertical motion can be reduced significantly in harsh sea conditions.

Study on a Mechanical Semi-Active Heave Compensation System of Drill String for Use on Floating Drilling Platform.

There are some disadvantages for existing heave compensation systems of drill string used for the Floating Drilling Platform (FDP), including high energy consumption, large and complex structure, and expensive manufacturing and maintenance costs. In view of the above, we present a streamlined mechanical semi-active heave compensation system (MSAHC) in this study. This system consists of active compensation part with the pinion and rack and passive compensation part. In order to evaluate system performance of the MSAHC, we establish its simulation model with AMEsim software. In the process of simulation, displacement of rotary hook and energy consumption is regarded as performance parameters of the system. And the change rule of two performance parameters are analyzed by changing these design parameters including gear radius of the pinion and rack, scale coefficient of PID, rotary hook load, heave height and heave period of the FDP, and accumulator volume. Then, based on the simulation results of the MSAHC system performance, we have selected out a best set of design parameters from them. Moreover, the feasibility of the design scheme of the MSAHC is effectively verified by comparison with the existing three heave compensation system. The result shows that the energy consumption of the MSAHC is lower than the active heave compensation system (AHC) and the semi-active heave compensation system (SAHC) when achieving a same compensation effect as well as the accumulator volume of MSAHC is half of the passive heave compensation system (PHC). Therefore, the new designed MSAHC not only ensure compensation effect but also lower energy consumption, and its structure is simplified by adopting the simple mechanical structure to decrease manufacturing cost, maintenance cost and floor space.

Real-Time Heave Motion Estimation using Adaptive Filtering Techniques

Active heave compensation (AHC) systems require an accurate estimate of the vertical vessel motion in order to decouple the offshore crane's lift operation from the motion of the vessel. In this work, the heave motion is estimated based on measurements from an inertial measurement unit (IMU) using an adaptive heave filter whose parameters are adapted online. A standard double integrating heave filter introduces large phase errors resulting in large estimation errors for real-time applications. This work presents three modifications of a standard heave filter in order to reduce those phase errors. The error composition of each proposed filter is analyzed. The results are used to derive error functions which are minimized in order to obtain the optimal filter parameters. Furthermore, sea state characteristics, such as the mean heave height and the dominant heave frequency are determined online and utilized for parameter adaptation. The real-time estimation accuracy improves significantly when applying the phase correction algorithms to the filters. This is evaluated using measurement results from the Liebherr AHC test bench.

Heave Compensation Control for Ocean Vessel

Heave compensation Control is usually used in vessels for offshore and deep-sea operations to reduce the adverse impact of unexpected vertical motion. This paper presents a control strategy for an active heave compensation system consisting of an electro-hydraulic system driven by a double rod actuator, which is subjected to parametric uncertainties and unmeasured wave disturbances. An adaptive robust controller is designed to guarantee the heave compensation error convergent to a bounded neighborhood around the origin. Simulations illustrate the effectiveness of the proposed control system.

Scientific Drilling

No abstract available. doi:10.2204/iodp.sd.15.08.2013

Adaptive robust control for an active heave compensation system

Active heave compensation systems are usually employed in offshore and deep-sea operations to reduce the adverse impact of unexpected vessel’s vertical motion on the response of underwater instruments. This paper presents a control strategy for an active heave compensation system consisting of an electro-hydraulic system driven by a double rod actuator, which is subjected to parametric uncertainties and unmeasured environmental disturbances. Adaptive observer and discontinuous projection type updating law with bounded adaption rate are presented firstly to estimate the uncertain system parameters. Then a similar estimation algorithm is designed by using a multiple delayed version of the system to enhance the performance of parameter observation. A reduced order observer is also introduced to estimate unknown wave disturbances. Using the obtained uncertainty information, the resulting control development and stability analysis are implemented based on the Lyapunov’s direct method and back-stepping technique. The proposed controller guarantees the heave compensation error convergent to a bounded neighborhood around the origin. Simulations illustrate the effectiveness of the proposed control system.

Heave Compensation System for Base Plate Used in Deep-Water Exploration Ship

This paper presents a heave compensation system for base plate used in 3000m deep-water exploration ship according to the sea conditions and the compensation requirements. The heave compensation system consists of a passive heave compensation system and an active heave compensation system. The passive heave compensation system with two hydraulic circuits and two air circuits is described, and the working principle is analyzed. The active heave compensation system, which consists of the hydraulic compensation cylinder, the hydraulic system using the closed-circuit and the electrical control system, is also established, and the working principle is investigated. The heave compensation system can keep compensation tension in the wire rope within certain range and make the rod run at design range (±500mm), which can avoid the serious equipment damage and a safety hazard to operators.

Riserless, Remotely Operated Technology Enables 10,000-ft Intervention Without Rig

Technology Update Intervention is necessary during the life cycles of most subsea wells. However, traditional methods can make it time consuming and very costly, with spread rates for drilling and semisubmersible rigs running at USD 1 million to USD 1.4 million per day. There are more than 4,000 producing subsea (wet tree) oil and gas wells worldwide, and the number is increasing by approximately 500 per year. With many wells more than a decade old, intervention is crucial to enable maximum oil and gas extraction. The sustained rise in deepwater exploration has made the need for cost-effective intervention on wet well trees even more pertinent. With the challenging conditions encountered in deep subsea settings such as Asia, Brazil, West Africa, and the Gulf of Mexico, many wells have produced for several years without necessary intervention. This often results in suboptimal production and reduced ultimate recovery. The AX-S system, developed by Expro, is designed to provide a safe, riserless, and remotely operated subsea well intervention method that can complete a typical deepwater intervention in six to eight days, compared with 10 to 12 days for a rig intervention, at a cost savings of approximately 75% to 80% based on lower day rates and speedier job completion. The system, designed and built over a seven-year development period with the input of more than 200 vendors, is in the final commissioning stage. Commercialization is expected later this year. Deployed from a monohull vessel (Fig. 1), the system is the first rigless intervention technology that can operate in waters up to 10,000 ft—several hundred feet deeper than the world’s deepest subsea well. The improved economics afforded by the system will allow operators to increase production and recovery rates in wet tree wells that otherwise might wait additional years for interventions. To enable deployment of the system, Expro has entered into a multiyear charter party contract with TS Marine Asia Pacific to use its dynamically positioned (DP) multiservices vessel Havila Phoenix for worldwide operations. The DP 2 Class vessel is 361 ft long and 75 ft wide with a moonpool of 23.6 ft by 23.6 ft, a 94-ton fiber rope drum winch with deployment tower, a 276-ton wire rope subsea crane, and two ultraheavy-duty Work Class remotely operated vehicles (ROVs) rated to more than 13,000 ft. The winch and crane are equipped with active heave compensation systems.

Modeling, simulation and design optimization of a hoisting rig active heave compensation system

The objective of this paper is to present an approach in developing a virtual active heave compensation system for a draw-works on a hoisting rig. A virtual system enables quicker overall product development time of a physical system as well as flexibility in optimizing the design parameters. Development of the virtual system started with the modelling of the draw-works and hoisting rig dynamics. Simulations of this model were run in two operational modes while subject to a sinusoidal wave: heave compensation and seabed landing of a payload. The results were analyzed and used for optimization in terms of cost and performance. This lays the groundwork for further testing either through hardware-in-the-loop testing (HIL) or using an actual prototype.

Heave Motion Estimation of a Vessel Using Acceleration Measurements

AbstractOcean waves continuously disturb every vessel resulting in horizontal and vertical motions. Especially the vertical motion has a significant effect on certain marine applications like subsea lifting operations. Subsea lifts are required for underwater installations on the seabed. Since such operations are normally performed from vessels using offshore cranes, the vertical vessel motion results in excessive dynamic loads acting on the crane structure. Furthermore, an accurate positioning of the load on the seabed is nearly impossible during harsh sea conditions. To avoid these problems active heave compensation systems can be used. These systems actively compensate for the vessel's vertical motion and therefore reduce the dynamic loads acting on the crane structure and enable precise positioning of the load. However, active heave compensation systems always require the knowledge about a vessel's heave motion. This article presents an observer based method to estimate the heave motion of a vessel from accelerometer signals without requiring any vessel specific parameters. The observer model is formulated by a sum of periodic components that approximate the heave motion of a vessel. The parameters of these components are identified online. The identified model is used with an extended Kalman filter to estimate the heave motion with high accuracy. The proposed method is evaluated with simulation and measurement results from an experimental setup.

High Performance Control of an Active Heave Compensation System

Abstract To compensate for heave motion, which has an adverse impact on the response of a drill-string or a riser, passive and active devices are usually used. Active heave compensators, whose control system is an essential part, allow conducting operations under more extreme weather conditions than passive ones. This paper presents a constructive method to design a nonlinear controller for an active heave compensation system using an electro-hydraulic system driven by a double rod actuator. The control development is based on Lyapunov's direct method and disturbance observers.

Nonlinear control of an active heave compensation system

Heave motion of a vessel or a rig has an adverse impact on the response of a drill-string or a riser. To compensate for heave motion, passive and active devices are usually used. Active heave compensators, in which a control system is an essential part, allow conducting operations under more extreme weather conditions than passive ones. This paper presents a constructive method to design a nonlinear controller for an active heave compensation system using an electro-hydraulic system driven by a double rod actuator. The control system reduces the effect of the heave motion of the vessel on the response of the riser by regulating the distance from the upper end of the riser to the seabed. The control development is based on Lyapunov's direct method and disturbance observers. The paper also includes a method to select the control and disturbance observer gains such that actuator saturations are avoided. Stability of the closed loop system is carefully examined. Simulation results illustrate the effectiveness of the proposed control system.

Adaptive wave synchronization for lowering of crane load

An adaptive observer for wave synchronization of an object through the wave zone is proposed in this article. The observer is based on measurements of the vessel accelerations in heave, pitch and roll, the winch motor position and the wire force. These measurements are normally available in active heave compensation systems. Comparison between wave synchronization and conventional heave compensation shows large improvement with respect to hydrodynamic forces on the object during wave synchronization. This is especially the case for large sea states.

An Operational Subsea Wireline System

This paper describes an operational subsea wireline system that is self-contained and flexible and offers a safe, economical, and proven method for riserless re-entry into any subsea well. The system discussed here was developed over a number of years and has been used to carry out a comprehensive range of wireline tasks from floating vessels in the North Sea. Although generally deployed from a diving support vessel (DSV), the system has been successfully used from a drilling rig to conduct wireline operations in a well, simultaneously with workover operations in an adjacent well, on a subsea template.