bluuebunny/crossref_metadata_2025_split huggingface dataset:
Random Vortex Method in Numerical Analysis of 2D Flow Around Circular Cylinder
Authors: Kostecki Stanisław 
Published: February 2015

Abstract
A combination of the vortex method and the boundary element method is used here to predict the two-dimensional flow field around a circular cylinder. Cylindrical structures experience strong hydrodynamic loading, due to vortex detachment from the both sides of cylinder during the flow. Thus, the practical meaning of such calculation is significant particularly in offshore oil and gas engineering as well as in the bridge and hydraulic structure engineering. This paper presents the mathematical formulation of the vortex method for the velocity and vorticity field calculation. The calculated velocity and vorticity fields are then used to predict the pressure distribution on the cylinder surface by the boundary element method. The resulting pressure on the cylinder, the Strouhal number and the length of the base recirculation zone are compared with solutions of other numerical methods and experiments, and a good agreement is achieved.
International Trade in Conflict Minerals: Solutions for the EU Regulatory Framework
Authors: Silná Zuzana , Kittová Zuzana 
Published: February 2015

Abstract
International trade in minerals, particularly tin, tungsten, wolfram, and gold, from conflict-
affected or high-risk areas can have significant implications on intensifying and
perpetuating the conflicts. It occurs that illegal mines are run by armed groups. As a
result, minerals acquired from such sources provide financial means to armed movements
and support the conflict. In this respect, several international and national regulatory
frameworks for responsible sourcing have been established. The most important
international initiative is the OECD Due Diligence Guidance for Responsible Supply
Chains of Minerals from Conflict-Affected and High-Risk Areas, which provides importers
with voluntary guidelines for responsible sourcing policy. In addition, the US
passed the Dodd-Frank Wall Street Reform and Consumer Protection Act in 2010. Section
1502 of the Dodd-Frank Act lays down the rules for responsible sourcing that are
compulsory for any company listed on the US stock exchanges. Following to these initiatives
and further public consultations, the European Commission and the European
External Action Service introduced a proposal for a comprehensive EU policy focused
on responsible sourcing of conflict minerals. The package consists of a legislative proposal
laying down rules for self-certification of responsible importers, as well as of additional
measures providing for support for SMEs and incentives for importers of conflict
materials. The aim of this paper is to analyse the legislative proposal and discuss
its possible implications given the fact that the EU legislation should be compatible
with standing frameworks.
Key Technologies for Developing Marginal Oil Fields in Offshore China
Authors: Xuwei Bie , Qinghong Yang , Xinwu Liao , Tran Thanh , Xunqi Liang , Chunrong Mu , Yong Hu , Tingli Li , Jinchang Su 
Published: February 2015

The majority were marginal oil fields among recent oil fields development projects in China's coastal waters. Because CNOOC's technical breakthroughs in reservoir, drilling and completion, production, and marine engineering, the efficiency of marginal oil field development in offshore China was clearly improved; resulting in a commercial value with huge comprehensive benefits for many marginal oil fields. This paper would use Oilfield ‘A’ in Bohai Bay Basin as an example to describe how a reservoir engineering team improved economics of a marginal oilfield with reserves less than 27 million barrels of oil.
First, reservoir engineering research sets the base for efficient development. The reservoir of oil field ‘A’ has the flow channel deposition with only two exploration wells to control nearly 27 million barrels reserves. In order to determine distribution and characteristics of the reservoir, the reservoir engineering team integrated seismic, geological, logging data, well shock calibration of fluvial sand body, detail interpretation of three-dimensional seismic and fine boundary portray, to describe fluvial reservoir sand bodies external morphology and its internal heterogeneity. Based on high-resolution three-dimensional seismic data, the team applied width-extrapolation method from well points and variogram analysis to establish the fluvial reservoir geological knowledge base. By integrating reserve distribution characteristics from analogous oilfield with dense well pattern, the team concluded with three types of well correlation models for fluvial reservoirs: vertical facies changes correlation, stacking sandbodies correlation, and incised channels correlation. The team used above three reservoir characterization techniques to determine the most likely reservoir distribution model of oilfield ‘A’.
Base on understanding of the reservoir internal structure, the reservoir engineering team actively explored the application of horizontal well development technology. By using numerical simulation to optimize the length of the horizontal section, the team analyzed vertical distance of well trajectory from the oil-water interface, studied impact of interlayer, evaluated benefit of horizontal injection well, developed practices in horizontal well suitable for channel deposition reservoir. The team utilized this model for designing oilfield development program and achieving maximum oilfield deliverability.
Advances in Compact Flotation Units (CFUs) for Produced Water Treatment.
Authors: Bhatnagar Mike , Sverdrup Carl Johan 
Published: February 2015

The Cameron TST-CFU is the next generation compact flotation technology that uses induced gas, dissolved gas and centrifugal forces to separate and remove hydrocarbons, aromatic compounds, hydrophobic substances and small solid particles from produced water. The technology uses special internals for mixing of gas and oil through several stages within one vessel.
Following extensive lab and field testing several full scale units have now been deployed. This next generation compact flotation unit is capable of handling higher inlet oil concentrations (over 1,000 ppm) and providing lower outlet OIW concentrations (less than 10ppm). The TST-CFU system requires less equipment, is less dependent on chemicals and can potentially replace multiple produced water treatment stages.
This presentation will outline the technology and present field operating data where the TST CFU has been used to replace conventional produced water treatment technologies. It will address the oil removal performance of the TST-CFU from fields with high OIW concentrations and small oil droplet size distributions.
The TST-CFU compact flotation unit, is specially designed to incorporate many new features which enhance equipment performance, reduce foot print, weight of equipment, reduce capital costs, operating costs, maintenance costs, and allows other applications including higher operating pressure and off gas containment.
A Simulation Approach for Optimisation of Gas Lift Performance and Multi-Well Networking in an Egyptian Oil Field
Authors: Yakoot Mostafa S. , Shedid Shedid A. , Arafa Mahmoud I. 
Published: February 2015

Gas lift has been applied successfully worldwide to increase well production. Artificial lift methods include pump assisted lift and gas lift. Gas lift is an artificial lift technique used to increase flow rate of oil wells. In this method, high pressure gas is injected into the well oil column to reduce its average density and make it flow to the surface.
The main objectives of this study are to (1) investigate the effects of injection gas gravity, and reservoir temperature on the performance of gas lift, (2) develop a total-system production-optimization model using PROSPER and GAP simulation programs, and (3) increase oil production through optimization of gas injected/fluid-produced oil ratio in an Egyptian oil field utilizing the existing compression capacity. The developed production model has been used for production optimization and allocation of lift gas in a multi-well network, as well as for prediction of future system requirements and identification of any bottlenecking opportunities. The attained results indicated that (1) artificial lift using gas lift is a complex process including several variables, which have been considered for optimization, (2) the optimization of gas injection rate increased the attained oil production, (3) gas gravity of injected gas has an important effect on attained oil production while reservoir temperature has shown minimal effect on oil production, and (4) gas lift optimization in Egyptian field can help in overcoming the high pressure gas (HPG) constraints, saving gas for the nearby oil field and increasing the total production for both fields. The developed production model is completely implemented, field wide optimization is pursued and multi-well networked model is established.
The application of the attained results is expected to have real impact in improving the gas lift performance in similar fields in the Middle-East and worldwide.
CFD Based Erosion Analysis for Design of Subsea Hardware in a High Flow Rate Gas Field
Authors: Singh Aditya , Sarkar Suranjan , Spritzer Jared M , Okeremi Akinyemi O 
Published: February 2015

Shell is developing an offshore gas-condensate field in Asia-pacific. Sand is expected to be co-produced during the life of this project due to minimal downhole sand control, which combined with high gas flow rate pose a significant threat to the integrity of the subsea hardware due to erosion. A Computational Fluid Dynamics (CFD) based erosion study has been carried out to identify the location of erosion hotspots and erosion rates in the piping of the subsea X-mas tree, well Jumper and Manifold. The study has been used to either determine Inconel 625 clad thickness to be provided on the inner wall of the piping or modify the design of the piping to bring the erosion within acceptable limits. The CFD models have been validated using experiments in controlled environment. Through this study, the risk of potential erosive failure of the piping in the subsea hardware, leading to loss of containment has been greatly reduced.
In literature, CFD based erosion modeling has been used and validated on simple geometries (elbow, target tee, ID reduction etc). In this work, erosion in the entire piping which is a combination of such simple entities has been calculated in an integrated manner.
The results show that the required cladding varies between 3mm and 10 mm. The knowledge about erosion acquired in the past through experimental and modeling exercises, has been utilized to create a technique to do assessment and management of sand erosion in the subsea hardware.
This integrated modeling approach provides insights about the behavior of sand particles in complex piping geometries, which can help design the piping, especially at locations of change in flow direction. The CFD model has also been used to determine the best location to place the IED (Intrusive Erosion Device) in the piping to monitor erosion during operation.
The Use of Direct Tension Monitoring of Mooring Lines in Reducing Conservatisms in Design and Analysis Models
Authors: Gauthier Steven , Elletson Edward 
Published: February 2015

The offshore oil and gas industry is continuing to push intodeeper water and onerous environments, using increasingly complicated vessels and equipment. This, combined with changing global weather patterns has increased uncertainty in offshore production operations. Monitoring mooring lines can help reduce this uncertainty by calculating fatigue damage estimates during major storm events. This greater understanding helps to optimise inspection and maintenance schedules and assess the likelihood of future mooring line failures. Added to this, if the deterioration or failure of a single mooring line is not detected, increasing loads on the remaining lines may result in additional failures. This is regarded as a system failure and could lead to significant consequences for both well control and riser integrity, resulting in huge costs for operators. Unless the operator inspects on a regular basis or monitors the mooring system in real time it is impossible to know for certain whether all mooring lines are in place.
A popular technique for monitoring mooring systems is tomeasure mooring line angle (using accelerometer based inclinometers), to infer theoretical mooring line tension. Whilst these systems are effective at alerting operators to a line failure, the fact that tension must be inferred requires a certain amount of conservatism in the estimate. This conservatism can be difficult to quantify. This paper documents the sea trial of a well proven mooring connector combined with new mooring line technology capable of measuring both mooring line angle and direct line tension. This allows for a unique comparison between the two measurements. This paper will detail the results of this comparison, showing the accuracy of inclination based monitoring systems and the level of conservatism factored in when tension is inferred. The data published in this comparison can be used to reduce levels of uncertainty in offshore operations and thus reduce future levels of conservatism in design and analysis models. This can help save costs and increase efficiency for future operations, whilst also helping support safetystrategies.
Design and Analysis of Cellular Tendon for TLPs in Ultra-Deep Water Fields Offshore Southeast Asia
Authors: Yu Jim 
Published: February 2015

TLPs (Tension Leg Platforms) are ideal platforms for drilling and dry trees in deep water oil and gas production worldwide. Currently there are over sixteen TLPs installed in regions including GOM, Southeast Asia, and West Africa. Several TLPs are planned for installation in West Africa and Brazil in the near future. The application of TLPs has reached a water depth limit that is around 1500 meters. The bottle-neck is the feasibility of the design of the tendon main body segments. Currently, the conventional tendon main body consists of a single string of steel pipes that in the ultra-deep waters cannot meet the combined requirements on stiffness and collapse resistance using the industry conventional installation methods. Other material such as carbon fibers were conceived as the tendon pipe material but are deemed as economically unviable.
The concept of the cellular tendon is developed to meet the industry's demands to go deeper for oil and gas production. It consists of multiple strings of carbon steel pipes bundled together to enable the TLP application in water depths up to 3000 meters. The general concept and merit of the cellular tendon design will be presented in reference [1]. This paper further demonstrates the applicability of the cellular tendon by providing in-depth design details and dynamic analysis results tailored for the fabrication and installation in South and Southeast Asia. The findings and the results presented in the paper can be utilized in the planning and design of a TLP in the ultra-deepwater of these regions. Reference [1]: Conference paper "Cellular Tendon - Enabling Technology for Ultra-Deep Water TLPs, 13OTCB-P-457-OTC".
Transforming Raw Subsea Sensor Data for Advanced Dynamic Positioning and Autonomous Functions in Real-Time for Asset Management and Remotely Operated Vehicle Operations
Authors: Menon Mahesh 
Published: February 2015

Oil and gas exploration is moving towards deeper waters, challenging geographical areas and dynamic working environments. This paper outlines the technology developments in an advanced control system embedding intelligent algorithms with sensor data in a closed loop, to perform various IRM tasks autonomously on a workclass remotely operated vehicle (WROV). Original analysis and field trial results are presented.
The data from the navigation sensors can be used to position and geo-reference the payload data, however, survey has relied upon expert piloting skills to maintain the WROV on a set course at a predetermined speed, heading and height from the seabed. In response to emergency situations, the equipment is hard to mobilise and the investment can be compromised if the WROV cannot be made to steer the course. This paper presents novel work in developing an autonomous control function suite integrated on a WROV to maintain a pre-laid course and offer a stable platform to gather data, and perform a task. Combined navigation functionality fuses data from GPS string, imaging sonars and a state-of-the-art phased array Doppler Velocity Log (DVL) with a Dynamic Positioning computer. Operators are equipped with the tools to survey and inspect their environment in a compact, easily deployable form factor.
This development highlights vehicle and umbilical positioning, movement logging, advanced vehicle controls (sophisticated cruise, mission planning and object/target recognition modules) and increased reliability. The Dynamic Positioning computer translates high-level mission requirements from a surveyor into automatic thruster commands providing automatic inspection and survey. Results from a selection of trials conducted with a major subsea operator using the system will be shown. The results demonstrate improvements in WROV control during transit, station keeping and conducting simulated riser inspection - via easy-to-use human-machine interface. The advance controls offer significant reduction in time and costs, and increased reliability, compared to pilots performing operations manually.
The technical industrial contributions of this technology are reduced training costs, mitigating lump sum risks by saving time in construction support operations, maintaining the quality and reliability of drill support operations, improving the quality of data for survey and IRM activities and providing better umbilical management.
New Elements in Geomechanics Submarine Rocks
Authors: Ciobanu P. , Avram L. 
Published: February 2015

Description of the Proposed Paper:
Professor Ciobanu has developed a new concept for defining and evaluating the effective stresses from discontinuous rocks. Starting from this concept, he succeeded in building up mathematic models that calculate effective values of the stresses from rocks with a more accurate precision than the previous models. A part of these results have been recently presented in conferences where they have been appreciated by the audience.
In this paper the authors present their own results obtained by applying and customizing the models mentioned above for particular cases of undersea rocks, involved in different offshore activities.

Application:
The information and results presented in this paper are useful and sometimes vital in evaluating of those deformations of undersea rocks that are important in case of some phenomena or technological operations, such as:–compaction and subsidence of rocks that constitute the basement for different equipment that are supported on the seabed or ocean bed;–hydraulic cracking, collapse or tightening in case of rocks that build up the offshore boreholes.

Results, Observations and Conclusions:
Practically, in this abstract there are presented the following:–a more developed model for the calculation of effective values of primary stresses of cohesive, porous rocks that build up reservoirs and undersea massive;–the way that the geometric parameters of pores, pore pressure, pressure on the seabed or certain physic-mechanic constants of rocks influence effective stresses.
The observations and the conclusions in the abstract have been stated based on the results obtained by numeric analysis. The basic models of the above stated concept have been previously verified in laboratory test.

Significance of Subject Matter:
The results from this paper are different from the others published in previous papers by the following elements:–the new model of calculation of effective stresses - herein proposed, is based on a concept more precise and accurate than the other known models;–the new introduced parameter for quantifying the form and pores distribution leads to unprecedented results and conclusions;–reduces risk of using such calculation models in situations where they are not compatible.
FLNG Cold Sea Water Intake Risers
Authors: Luppi Ange , Mayau David 
Published: February 2015

Natural Gas is today recognized as the energy of the future and therefore a cost-effective means to transport the produced gas from the producers (e.g. Australia, Indonesia) to the users (e.g. Japan, China) is a prerequisite for the world economic development and environmental protection.
One such initiative is the recent development of Floating Liquefied Natural Gas (FLNG) units which requires a lot of cold sea water to increase gas liquefaction process efficiency.
At 160m below sea surface, the water temperature is 10°C lower than at surface and up to 16°C lower at some 320m water depth. These would be the required lengths for the water intake risers to enable the LNG process.
The paper starts with a detailed description of the Trelleborg bonded flexible hoses with large internal diameter (i.e. up to 1m ID) and its main particulars (e.g. embedded flange connectors, variable integrated bending stiffener) to suit with the conditions of use and in particular the "cyclonic" environmental conditions.
Different riser configurations will be presented, e.g. distributed risers along the ship side(s) or bundled together at a dedicated topside deck location, with its pros & cons, as well as the outline installation procedures with typical marine spread vessels.
The paper will include the riser design methodology with references to industry codes & standards, recommended practices, etc. Typical functional loads and "Asia" environmental load case matrix will be presented.
Lateral Buckling Design for Intermittently Buried and Spaning Pipelines
Authors: Roberts C. , Taavale J. 
Published: February 2015

High pressure/high temperature (HP/HT) pipelines are potentially susceptible to global buckling which can result in failure unless properly managed. Traditionally global buckling has been prevented from occurring by restraining the pipeline; however an alternative solution is to control the high effective force that occurs in the system by providing a planned buckle initiation scheme.
Design guidelines and standards such as SAFEBUCK offer comprehensive guidance to design for global buckling. However, the current industry approach does not account for areas of high seabed mobility where effective frictional restraint can vary significantly along a pipeline route, over a short distance. The effect of this phenomenon on global buckling design is discussed in this paper and a refined design approach presented.
The conventional method is to perform global buckling design considering lower bound friction to assess the propensity for buckling and upper bound friction to assess the post buckle response. This approach is sufficient when considering a conventional range of possible frictional restraint – i.e. in the North Sea / Arabian Gulf. However, in areas of high sediment mobility e.g. NWS Aus. a much wider range of soil restraint may occur as a result of spanning and burial of pipelines created by the mobile seabed. Utilising the standard approach may result in very conservative design, for instance with the requirement to restrain the pipeline rather than control global buckling.
This paper presents a more refined approach by taking the existing soil restraint and assessing if global buckling can still occur, in this manner the upper bound friction is refined to a lower value at which a global buckle can feasibly initiate. Reducing the frictional restraint range allows a controlled buckling scheme to become feasible and a more cost effective design to be adopted.