A Static Analysis of Hydraulic Heave in Cohesive Soil

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Motion Control of Hydraulic Winch Using Variable Displacement Motors

The paper II is excluded from the dissertation with respect to copyright.To compete in the open market of the offshore crane industry, it is imperative for the manufacturer to continuously improve crane operability. In this context, the crane operability is expressed by means of a so-called weather window. The weather window is computed from the crane characteristics in combination with that of the vessel and the payload to be handled. It returns a set of boundaries for when it is accepted to perform a planned lift, mainly in terms of current sea-state and wind. The most important crane operability characteristics that enter into the computation of the weather window are maximum wire velocity and load capacity. This thesis focuses on how to improve the operability of active heave compensated offshore cranes. Two ways of achieving that goal have been investigated, namely, an improved control strategy and the use of model-based lift planning. The system investigated is the hydraulic active/passive winch system used by National Oilwell Varco. A new control strategy for the system was developed, tested, and implemented. The new strategy utilizes that variable displacement of the hydraulic motors of the active system of the winch drive. The strategy, semi secondary control, gave significant benefits in terms of reduced peak-pressure, increased load capacity, increased wire-speed capacity, and smoother winch performance at low winch speed. The results were validated and verified through simulations and in-field measurements.publishedVersio

Interdisciplinary design methodology for systems of mechatronic systems focus on highly dynamic environmental applications

This paper discusses a series of research challenges in the design of systems of mechatronic systems. A focus is given to environmental mechatronic applications within the chain “Renewable energy production - Smart grids - Electric vehicles”. For the considered mechatronic systems, the main design targets are formulated, the relations to state and parameter estimation, disturbance observation and rejection as well as control algorithms are highlighted. Finally, the study introduces an interdisciplinary design approach based on the intersectoral transfer of knowledge and collaborative experimental activities

Safety related study of Expanding Pin systems application in lifting and drilling equipment within Construction, Offshore, and Marine sectors

A questionnaire-based survey has been performed among original equipment manufacturers (OEMs), sub-suppliers, engineering companies, end-users, service & maintenance, and “others”, as part of an investigation to clarify their relationship to expanding pin system, compared to standard, cylindrical pins. In addition, a short literature study on onshore cranes is conducted. The survey is based on 9 questions about safety for personnel and machine, breakage, and wear of pins and supports, and installation and retrieval easiness of pins. The analysis of the responses indicates that safety for personnel and machines/equipment is regarded mainly as either “Important” or “Crucial and decisive”, and that the expanding pin solution is regarded as “better” or “equal” compared to the standard, cylindrical pin, both for “safety level”, “risk for breakage of pin & support”, “tear & wear on pin & support” and “installation and retrieval time”.publishedVersio

Manipulation of the choke pressure during Managed Pressurized Drilling (MPD) operation

Master's thesis in Petroleum EngineeringIn the present investigation, the disturbance and its effect on the bottom hole pressure has been studied. After digging into the prior works, it’s figured out that the reason of their failure is oversimplification and ignoring some parameters that have considerable impact on the BHP like frictional forces resulting from fluid and drill string movements. Following the weakness of the last studies, the feasibility of applying new hydraulic model has been studying and new assumptions have been presented. The model is provided by a set of linked PDEs 1. the pressure dynamics of the well annulus during unsteady Couette flow with a pressure gradient; 2. The movement of the elastic drill string coupled with the pressure dynamic through viscous friction and displacement of drilling mud. It is shown how the model can be simplified to a linear system and under which assumption this simplification can be proceeded. By using the Laplace transformer and inserting appropriate boundary conditions, the transfer function is derived from the linear system. The resulting model uses heave disturbance and controlled flow into the wellbore as input, and the measured pressure at the top of the well, as well as the pressure at the bottom of the well as output. Based on the Hydraulic model developed, for the sake of simplification and faster running time, a lower order of the model with fewer control volumes have been introduced for the Model Predictive Controller (MPC). Two control algorithms for both normal and intervention operations have been evolved by application of PID and Model Predictive Controller (MPD). The Optimization of the PID controller has been done theoretically and validified by MATLAB

In situ enhancement of well recovery by pneumatic media injection

The objective of this thesis was to develop a new process for enhancing recovery wells at hazardous waste sites. The process, known as an extended radius well (ERW), involves injection of ceramic beads directly into groundwater plumes to create drainage paths for liquid contaminants. This is a variant of Pneumatic Fracturing, which is a patented in situ remediation process developed to increase permeability of soil and rock formations by injection of high pressure gas. The research study comprised laboratory investigations, engineering scale tests, and a field pilot demonstration. The laboratory investigations examined the properties of several candidate media to determine their gradation, permeability, mechanical strength and flowability. Ultimately, ceramic beads were chosen for use in the field demonstration. Engineering scale injection tests were subsequently conducted in a 20 yd3 (15.3 m3 ) vessel filled with silty sand to establish system operating parameters. A field pilot demonstration of the ERW process was performed at an industrial site underlain by silty fine sands containing a plume of petroleum hydrocarbons. Two ERWs were established and pumping tests performed over an 85 day period. The two ERWs displayed average increases in product recovery of 225% and 335%, respectively, compared with previous results from conventional recovery systems. Soil borings confirmed that discrete lenses extended outward from the ERWs, and model analyses attributed the observed enhancement to an increase in effective well diameter

Determining the Optimal Number of Pistons for Offshore Digital Winch Drives

In offshore winch drive applications, determining the required number of pistons in digital displacement motors is critical for minimizing torque ripples. Digital displacement motors have shown promise for improving energy efficiency for offshore operations, such as placing equipment on the seabed or mineral drilling. However, they are known for exhibiting significant torque ripples, which can affect load-handling precision. This paper estimates the required number of pistons for realizing a digital hydraulic winch drive based on information from a commercial winch. The proposed drive employs full-stroke displacement strategies at high speeds and partial-stroke at low speeds. By simulating steady-state operations, this study correlates torque output with position oscillations. The results show that 37 pistons are required to keep position oscillations below a benchmark threshold of 10 mm throughout the drive’s operating range to avoid hindering the drive’s performance. However, such a high piston count could result in high costs due to the large, expensive valves required for partial-stroke operations. Therefore, this paper suggests an alternative drive topology for future research, which could potentially reduce the number of pistons that are operated with partial strokes

Ground-freezing experience on the east side access Northern Boulevard crossing, New York

A brief review is given of ground freezing technology as a means of providing groundwater cut-off and temporary structural support in weak ground for transportation tunnelling and shaft-sinking operations. Then detailed coverage of a particular case history is reported in variable soils in Queens, New York. As part of the upgrading of rail access from Long Island into Manhattan, a tunnel was required that necessitated a frozen arch structure under a ‘live’ roadway and rail lines. The installation, development and performance of the frozen zone are described. At two small locations groundwater continued to flow through the line of the frozen arch, the heat in the newly arrived groundwater being greater than the capacity of the ground freezing technique to remove that heat, thereby preventing final ‘closure’ by frozen soil at those points. The remedial works to overcome these difficulties are described. Some conclusions are drawn concerning the reasons when and why these localized unfrozen ‘windows’ can be anticipated in freeze zones and about the requirements for remedial solutions

A Wave Simulator and Active Heave Compensation Framework for Demanding Offshore Crane Operations

Abstract-In this work, a framework is presented that makes it possible to reproduce the challenging operational scenario of controlling offshore cranes via a laboratory setup. This framework can be used for testing different control methods and for training purposes. The system consists of an industrial robot, the Kuka KR 6 R900 SIXX (KR AGILUS) manipulator and a motion platform with three degrees of freedom. This work focuses on the system integration. The motion platform is used to simulate the wave effects, while the robotic arm is controlled by the user with a joystick. The wave contribution is monitored by means of an accelerometer mounted on the platform and it is used as a negative input to the manipulator's control algorithm so that active heave compensation methods can be achieved. Concerning the system architecture, the presented framework is built on open-source software and hardware. The control software is realised by applying strict multi-threading criteria to meet demanding real-time requirements. Related simulations and experimental results are carried out to validate the efficiency of the proposed framework. In particular, it can be certified that this approach allows for an effective risk reduction from both an individual as well as an overall evaluation of the potential harm