bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permanent Plug and Abandon of a Subsea Well With Obstructed Well Access: A Success Story
Authors: Stanislawek Mikolaj 
Published: September 2018

Permanent Plug and Abandon (PP&A) operations of the existing production and exploration wells continue to have a higher focus in drilling and well operations for Oil & Gas Companies. It is expected that they will play an important role in the future, and their further optimization and simplification is even more important. This paper describes a successful approach and execution of a challenging Permanent Plug and Abandon operation of a subsea well in the Norwegian Sea by Statoil.
A subsea well at over 350 m water depth was being drilled, when a casing running tool was stuck at the subsea wellhead when running an intermediate casing string. This led to a temporary well abandonment, before permanent P&A operations could be resumed at a later stage. Several concepts and contingency scenarios were evaluated and risk assessed in the planning phase, which required implementation of nonstandard and innovative P&A solutions and equipment. They were developed in the planning phase and reviewed with planning and execution teams, and tested before the operational start-up. Main P&A operational goals were established in the planning phase, and successfully implemented during the operations: 1) well control — confirm there is no gas and no well control risk in the well before resuming P&A operations, 2) gain access to the well by retrieving stuck tool from subsea wellhead, and 3) establish permanent P&A barriers in the well.
Both planning and execution of this operation is described in this paper, which includes main planned operations, and also a strategical approach with several contingency scenarios prepared in order to be able to P&A this well permanently.
Improving the Safety of Fishing Vessels Through Roll Motion Analysis
Authors: Santiago Caamaño Lucía , Míguez González Marcos , Díaz Casás Vicente 
Published: September 2018

Fishing sector is one of the most dangerous worldwide. Accidents are usually related to stability failures that can be due to static or dynamic phenomena. Their main cause is the crew lack of training in stability matters, especially in small-medium sized fishing vessels. The vast majority of fishermen assess the risk level of their ship carrying out a subjective analysis, based on their previous experience.
In order to reduce the number of stability-related accidents, onboard guidance systems were proposed in the last years as a tool that helps the skippers to evaluate the ship stability in an easy and understandable way.
The authors of this work have proposed their own alternative, which consists on a simplified stability guidance software installed on a touchable-screen computer.
In its initial version, this software relied in data manually introduced by the crew and only considered static stability for the evaluation of the vessel safety index. In the version presented in this paper, the authors have tried to solve the need for manual data applying a methodology for the real-time estimation of the roll natural frequency of the vessel. In addition to this, environmental conditions and the evaluation of dynamic stability vulnerabilities based on the IMO Second Generation of Intact Stability Criteria have also been included.
Station-Keeping Trials in Ice: Overview of Ice Management Support
Authors: Neville Mike , Almkvist Erik , Scibilia Francesco , Lindvall Joakim K. , Liferov Pavel 
Published: September 2018

In March 2017, Statoil performed station-keeping trials in drifting ice in the Bay of Bothnia. The anchor handling tug supply vessel Magne Viking, performed station keeping operations in various ice conditions, including managed and non-managed ice. Physical ice management was used to manage the approaching ice to a target condition suitable for the station keeping tests, and to enable other essential operations including deployment and retrieval of the mooring spread and other equipment. Given the objective of the trials, physical ice management activities were performed in such a way to allow investigation of various relevant parameters that influence the managed ice condition. Additional tests were also performed for the sole purpose to assist with validation of Aker Arctic’s ice management software “AIMS”, including tests designed to estimate the performance of the vessels under different ice conditions.
This paper focuses on the physical ice management operations performed by the ice management vessel Tor Viking (TV) during the Station Keeping Trials in ice (SKT). Also included is a discussion on how AIMS was used in the planning phase and how simulations compared with actual observations.
Analysis of Semi-Submersible Under Combined High Waves and Current Conditions Compared With Model Tests
Authors: Yang Limin , Nestegård Arne , Falkenberg Erik 
Published: September 2018

Viscous effects on the low-frequency excitation force on column based platforms are significant in extreme waves. The wave drift force as calculated by a zero-current potential flow radiation/diffraction code becomes negligible for such waves. In the present study, the effect of current and viscous contributions on the slowly varying wave forces are adjusted by a formula developed in the Exwave JIP, see e.g. [1], which is validated against model test results.
This paper presents numerical predictions of low frequency horizontal motions of a semi-submersible in combined high waves and current condition. In the simulation model, frequency dependent wave drift forces from radiation/diffraction code are modified by the formula. Static current forces and viscous damping are modelled by the drag term in Morison load formula using relative velocity between current and floater and with force coefficients as recommended by DNVGL-RP-C205 [2]. Low frequency surge responses calculated by the simulation model are compared with model tests for waves only and for combined collinear and noncollinear wave and current conditions.
Retracted: “Kinematic Analysis of the Motion of a Six Degrees of Freedom Wave Energy Converter Based on the Concept of the Stewart-Gough Platform” [ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, Volume 10: Ocean Renewable Energy, Madrid, Spain, June 17–22, 2018, Conference Sponsors: Ocean, Offshore and Arctic Engineering Division, ISBN: 978-0-7918-5131-9. Paper No. OMAE2018-78601, pp. V010T09A047; 10 pages, doi:10.1115/OMAE2018-78601]
Authors: ASME  
Published: September 2018

This paper was withdrawn. ASME does not hold the copyright. December 21, 2018.
Copyright © 2018 by ASME
Parameter Estimation for Synthetic Rope Models
Authors: Weller S. D. , Banfield S. J. , Canedo J. 
Published: September 2018

With widespread market penetration in the offshore sector, synthetic rope materials offer a range of axial compliance that can be exploited for mooring design, ranging from stiff (e.g. high modulus polyethylene) to soft (e.g. nylon). For new applications, such as the marine renewable energy (MRE) sector synthetic ropes are potentially an enabling technology due to their load reduction properties and relative low cost compared to conventional mooring component materials.
Existing design, test and certification procedures for ropes were developed for the station keeping of large offshore equipment. Arrays of small, reactive MRE devices will have an entirely different set of mooring load cases with the mooring system potentially an integral part of the power take off system. Larger devices are also likely to be subjected to complex loading as MRE deployment sites are typically highly energetic in terms of wind, wave and/or tidal energy. Consequently devices and associated subsystems are subjected to dynamic load cases in a wide range of complex environmental and operating conditions. Underpinning research is therefore required to understand the behaviour of synthetic materials subjected to highly dynamic loading regimes in terms of operational performance and long-term durability as these factors could have a significant impact on coupled device performance and availability. At present conventional mooring analyses is based on the use of simplified rope characteristics, although several studies including a Joint Industry Project (Syrope) have investigated these aspects. However, at present an industry-standard method to account for the time-varying behaviour of synthetic ropes for offshore equipment moorings does not exist.
The SynMaRE (Synthetic ropes for Marine Renewable Energy mooring systems) project aims to develop a time domain analytical model that can adequately represent the time dependent and non-trivial behaviour of synthetic ropes. Instead of being a stand-alone tool, it is intended that the model will be adopted for incorporation in (or with) commercial mooring system software allowing the prediction of mooring loads and device responses to an increased level of accuracy. This paper will present findings from an initial assessment of parameter estimation techniques utilising a simplified viscoelastic and viscoplastic model and validation scenarios based on physical tension-tension test data featuring load cases relevant to MRE mooring systems.
Numerical Study of Phase Change Influence on Wave Impact Loads in LNG Tanks on Floating Structures
Authors: Ancellin Matthieu , Brosset Laurent , Ghidaglia Jean-Michel 
Published: September 2018

Understanding the physics of sloshing wave impacts is necessary for the improvement of sloshing assessment methodology based on sloshing model tests, for LNG membrane tanks on floating structures. The phase change between natural gas and liquefied natural gas is one of the physical phenomena involved during a LNG wave impact but is not taken into account during sloshing model tests.
In this paper, some recent numerical and analytical works on the influence of phase change are summarized and discussed. For the impact of an ideally shaped wave, phase change influences two different steps of the impact in different ways: during the gas escape phase, phase change leads to a higher impact velocity; for entrapped gas pockets, phase change causes a reduction of the pressure in the gas pocket. However, this influence is quantitatively small.
The generalization to more realistic wave shapes (including e.g. liquid aeration) should be the focus of future works.
Decision Making Through the Application of Bayesian Network for Internal Corrosion Assessment of Pipelines
Authors: Ayello Francois , Liu Guanlan , Zhang Jiana 
Published: September 2018

Decision making for a new pipeline’s design and provision of the most effective maintenance or repair measures for a pipeline in operation can be a long and costly process. The final decision made, whether during design or operation, may not always reduce the risk or remediate the threat. This is mainly due to the uncertainty and missing information regarding the field chemistry for current and future pipeline operating conditions, that were not considered and quantified during the assessment.
In this paper, two case studies of pipeline internal corrosion risk are presented, one for pipeline in design and the latter for pipeline in operation. Both cases were assessed using Bayesian Networks. Bayesian Networks (BN) have been used to quantify the value of information of uncertain and missing data. BN displays the cause-effect relationships of these data in the form of conditional probabilities to describe how one’s data is influencing internal corrosion rates probability. Thus, predicting the pipeline’s conditions over the design life. Operators can visualize the development of internal corrosion within a pipeline over time and gain clearer understanding of the causal relationships that could lead to pipeline failure. The results allowed operators to confirm the effects of the parameter and followed by a sensitivity analysis to find out which data to prioritize in acquisition and validation before proceeding to decide on how the pipeline should be designed and maintained/inspected in future.
Rheological Properties of Barite Sediments in Water-Based Drilling Fluids
Authors: Vrålstad Torbjørn , Skorpa Ragnhild , Saasen Arild 
Published: September 2018

When a drilling fluid column remains static over a timeframe of several years, the drilling fluid separates into different sediment phases due to gravity separation. These heavy sediments, entitled “settled barite”, are the cause of significant operational problems several years after drilling.
An important problem caused by settled barite occurs when performing casing cut-and-pull operations during slot recovery and well abandonment: the casing is “stuck” due to the sediments in the annulus outside the casing. The consistency and rheological properties of the sediments determine how easily the casing is removed.
In this paper, we report a preliminary study were we have artificially prepared gravity sediment phases for two different types of water-based drilling fluids; one KCl/polymer-based fluid and one bentonite-based fluid. By studying the rheological properties of the obtained sediment phases, we see that there are considerable differences between the sediments for these different drilling fluids.
Effect of MWCNT and MWCNT Functionalized -OH and -COOH Nanoparticles in Laboratory Water Based Drilling Fluid
Authors: Alvi Muhammad Awais Ashfaq , Belayneh Mesfin , Saasen Arild , Fjelde Kjell Kåre , Aadnøy Bernt S. 
Published: September 2018

In recent years, the application of nanomaterial has been attracting the oil and gas industry. Nanomaterials research results show an improving performance of cement, drilling fluid and enhanced oil recovery.
In this paper, the effect of multi-walled carbon nanotube (MWCNT) and MWCNT functionalized with ligands–OH and - COOH nanoparticles on laboratory drilling fluids formulated from bentonite, KCL, Carboxymethyl cellulose (CMC) and xanthan gum (XG) was studied. The formulations and tests were performed at room temperature.
The results show that addition of 0.0095wt.% of MWCNT, MWCNT-OH and MWCNT-COOH nanoparticles in CMC/bentonite system decreases the filtrate-loss by 8.6 %, 7.1 % and 17.9 % respectively. These particles also decreased the coefficient of friction by 34 %, 37 % and 33 % respectively. In xanthan gum drilling fluid, 0.019wt%. MWCNT reduced the friction coefficient by 38 %.
Performance of a Wave-Energy-Converter Array Operating Under Model-Predictive Control Based on a Convex Formulation
Authors: Zhong Qian , Yeung Ronald W. 
Published: September 2018

Economics decision drives the operation of ocean-wave energy converters (WEC) to be in a “farm mode”. Control strategy developed for a WEC array will be of high importance for improving the aggregate energy extraction efficiency of the whole system. Model-predictive control (MPC) has shown its strong potential in maximizing the energy output in devices with hard constraints on operation states and machinery inputs (See Ref. [1–3]). Computational demands for using MPC to control an array in real time can be prohibitive. In this paper, we formulate the MPC to control an array of heaving point absorbers, by recasting the optimization problem for energy extraction into a convex Quadratic Programming (QP) problem, the solution of which can be carried out very efficiently. Large slew rates are to be penalized, which can also guarantee the convexity of the QP and improve the computational efficiency for achieving the optimal solution. Constraints on both the states and the control input can be accommodated in this MPC method. Full hydro-dynamic interference effects among the WEC array components are taken into account using the theory developed in [4]. Demonstrative results of the application are presented for arrays of two, three, and four point absorbers operating at different incident-wave angles. Effects of the interacting waves on power performance of the array under the new MPC control are investigated, with simulations conducted in both regular and irregular seas. Heaving motions of individual devices at their optimal conditions are shown. Also presented is the reactive power required by the power takeoff (PTO) system of the array to achieve optimality.
We are pleased to contribute this article in celebration of our collegiality with Professor Bernard Molin on the occasion of his honoring symposium.
A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects: Uncertainty and Sensibility Analysis
Authors: Oliveira Nara , Netto Theodoro 
Published: September 2018

The collapse pressure of pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. The severity of each individual corrosion defect can be determined by comparing the differential pressure during operation with the estimated collapse pressure. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto (2010). This formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries.
However, loads and resistance parameters have uncertainties which define the basic reliability problem. These uncertainties are mailyrelated to the geometric and material parameters of the pipe and the operational conditions.
This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto (2010) is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. Finally, a sensitivity analysis is performed to identify how geometric parameters of the defects influence the reduction of collapse pressure.
A Unified Approach for Estimating of the Drag Coefficient in Offshore Structures in Presence of Bio-Colonization
Authors: Bakhtiari Arash , Schoefs Franck , Ameryoun Hamed 
Published: September 2018

Due to increase of global demand for renewable energies, assessment of environmental forces become an important aspect of offshore structures which is the key to ensure optimized and reliable development of this industry. The present study aims to bring out an integrated approach to drag coefficient estimation for circular cylinders covered by biocolonization. Hard and long flapping (Kelp) species were chosen as the study area to demonstrate the effect of biofouling. An integrated approach including the percentage of cover, surface roughness ratio, biofouling species, and aggregating pattern was employed to investigate the steady state drag force coefficient. Several experimental data were collected from previous researchers considering afore-mentioned parameters.
This paper proposes two independent equations for hard and long flapping biofouling using regression analysis method. Both equations were compared with experimental data; a multivariate statistical analysis by Taylor diagram was also performed resulting in reasonable values.
It is worth mentioning that the present work is part of a wider study concerning the effects of biofouling components on the hydrodynamic forces of structures such as jackets and floating offshore structures. The first part of the study considered the investigation of the existing data.
Casing Collapse Design Using Structural Reliability Analysis for a Subsea Well on the Norwegian Continental Shelf
Authors: Buchmiller David , Bjørset Arve , Hørte Torfinn , Pettersen Sune 
Published: September 2018

Casing collapse capacity was identified by Statoil as a critical operational parameter on one of its fields in production. This facilitated the need to re-evaluate the overall well design, specifically the production casing’s collapse capacity. Studies were performed to analyze and objectively increase the documented casing collapse capacity, while maintaining the safety level.
Initially, the casing collapse capacity was evaluated using API TR 5C3 / ISO 10400, with insufficient capacity being documented. In order to investigate further, physical material testing and collapse testing were performed. Detailed finite element analysis was used to evaluate the casing collapse capacity, given well specific input parameters. The four critical parameters of axial load, casing ovality, casing wear, and temperature-dependent material properties were identified and the importance of each parameter was mapped. Using the testing results and the finite element models as a basis, structural reliability analysis (SRA) was applied to calculate the probability of failure for casing collapse of the production casing as a function of the differential pressure.
The SRA provided results for the spread of the field and for individual wells given specific input on the key parameters of casing ovality, wear and temperature. At the selected target reliability level, the SRA results showed a higher collapse capacity of the production casing relative to conservative calculations commonly used from API TR 5C3 / ISO 10400 for well design.
Applying SRA to well design, specifically collapse evaluations, has proven useful in concluding on the probability of failure. The SRA has transformed improved knowledge from testing and measurements to reduced uncertainty and a corresponding reduction in the failure probability. The potential over-conservatism in the conventional deterministic analysis is then avoided, while maintaining the overall safety level. The SRA results were used to assist in the risk evaluation resulting in an allowance for continued production on existing wells.
User Interface Design Guidelines for Marine Autonomous Operations Involving a Large Number of Actors, Devices and Sensors
Authors: Poranen Hanna , Marafioti Giancarlo , Johansen Gorm , Sæter Eivind 
Published: September 2018

User interface (UI) is a platform that enables interaction between a human and a machine, a visual part of an information device, such as a computer or software, which user interacts with. A good user interface design makes operating a machine efficient, safe and user friendly in a way that gives the desired result.
This paper describes a set of guidelines defined for marine autonomous operations where many actors, devices and sensors are interacting. The UI should manage and present in a user-friendly manner a large amount of data, ensuring situation awareness for the operator/user. The design guidelines of the user interface consist of both a work process part and a content part, also called user experience design (UX). The work process consists of four sections: manage, plan, operate and evaluate, while the content part focuses on how to show the information. Both parts will be detailed and discussed and can be taken as a reference for designing user interfaces in particular for marine autonomous operations.