bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insights from CFD Validation of a Jackup Rig
Authors: Barczak Nicholas A. , Reifsnyder Jefferey D. , Mobbs Charles B. 
Published: April 2016

Abstract
The authors performed a computational fluid dynamics (CFD) analysis of a self-elevating mobile offshore drilling unit (SE MODU) as a replacement for wind tunnel testing. The authors utilized an unsteady RANS method to model wind forces on an SE MODU for a variety of wind headings. The simulation produced force and moment data for individual structural components of the SE MODU. The final data set presented sufficient information to calculate overturning moments of the SE MODU in a range of wind conditions.
This paper discusses several techniques developed for the SE MODU analysis: meshing of disparate structural scales, accurate simulation of large intricate structures, and accurate description of dynamic effects. The paper presents methodology for calculation of a center of effort that correctly relates vector force to vector moment in all three dimensions. The authors demonstrate that center of effort was not appropriate to dynamic flow situations; direct moment coefficients were more suitable.
As part of the validation process, CFD analysis was performed on a similar SE MODU design and compared to existing wind tunnel results. This paper compared forces and moments in all three axes for multiple wind headings. The CFD analysis compared very well with wind tunnel results, showing only a 10% difference from the experiment.
The project revealed several advantages of CFD over traditional wind tunnels in this application. The insights from CFD showed the contribution of each structural component to overturning moment, and results revealed significant elements of overturning moment not considered by the current industry standards. CFD analysis required a similar level of effort as a wind tunnel test but produced far more detailed knowledge.
Probabilistic Analyses for Lateral Buckling of Pipe-in-Pipe Systems
Authors: Gitahy Leonardo , Charnaux Carlos , Manso Daniel , Roberts Graeme 
Published: April 2016

In order to meet the growing demand for oil production in even deeper waters, new technologies have been developed, making the exploration of such fields possible. A system used as an alternative for the control of extreme operating conditions (high temperatures and pressures) of such exploration fields is the pipe-in-pipe system. This kind of system is extensively used in offshore applications in which exceptional thermal insulation capability is required, preventing hydrate/wax formation and maintaining the production temperature up to the arrival facilities.
However, extreme operating conditions can cause the system to experience thermomechanical buckling, which can lead to a structural failure of the system. In order to control these thermomechanical loads and ensure that pipeline is within a safe operating margin, the potential buckling formation locations need to be assessed and may need to be mitigated. The key point in the thermomechanical design of offshore pipelines is to define whether the buckling phenomena should be controlled or not. The optimal solution may often involve addressing natural imperfections whilst establishing the required engineered mitigation measures.
Design assumptions such as the pipeline as-laid lateral Out-Of-Straightness (OOS) and the pipe-soil interaction parameters are common input data uncertainties existent during design of HP/HT offshore pipeline systems. A robust design should be impervious to variations in the values of these design parameters, considering values that lie within reasonable and feasible limits, such that the project can proceed with reasonable certainty and within sensible cost limits. In this scenario full of uncertainties, reliability analysis has been implemented in the thermomechanical design of offshore pipeline systems. The purpose of reliability analysis is to reduce the design conservatism by quantifying the probability of failure associated with the pipeline system.
This paper presents a novel and viable proposal for conducting probabilistic analysis associated with lateral buckling of a full length pipe-in-pipe system, through the application of detailed finite element analysis. The information contained in the paper can be used as guidance for future reliability evaluations of offshore pipeline systems.
Normalized Modulus Reduction and Material Damping Ratio Curves for Bay of Campeche Sand
Authors: Taboada Victor M. , Dantal Vishal , Roque Diego Cruz , Lopez Francisco Flores , Nabor Procoro Barrera 
Published: April 2016

Abstract
Predictive equations for estimating normalized shear modulus and material damping ratio of sand are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing isotropically consolidated resonant column and strain-controlled cyclic direct simple shear test results for 252 specimens obtained from the Bay of Campeche. Two independent modified hyperbolic relationships are fitted to model stiffness (G/Gmax)-strain using two parameters and material damping ratio-strain curves using four parameters. Variables used in the equation for normalized shear modulus are: confining pressure; shear-strain amplitude; a reference strain, defined as the shear strain at which the shear modulus has reduced to 0.5Gmax, and a curvature parameter which controls the rate of modulus reduction, such as the model suggested by Darendeli (2001). The equation for damping ratio D, is expressed in terms of the reference strain, defined as the shear strain for a 50% increase in material damping ratio (i.e. D/Dmax = 0.5), a curvature parameter which controls the rate of material damping ratio increase, the minimum material damping ratio Dmin, and the maximum material damping ratio Dmax, similar to the equation suggested by Gonzalez and Romo (2011). It is found that the Bay of Campeche sand exhibit more linear response and lower damping ratio than other sands reported in the literature. The uncertainties associated with the predictive equations are quantified. A case study is provided to illustrate an application of the predictive equations to seismic response analysis and the importance of considering confining stress. The predictive equations of normalized shear modulus reduction G/Gmax and Damping ratio curves are easy to apply in practice, and are useful in the analysis of granular strata and offshore structures subjected to earthquake loading when site specific laboratory testing is not available.
Removing Marine Growth Using an ROV with Cavitation Technology
Authors: Restivo Andrew , Brune Michael 
Published: April 2016

Marine growth on the submerged hull of a floating offshore installation can prevent the effective inspection of external hull plating, weld, and coating. Subsequently, several countries throughout the world have established regulations addressing inspection and maintenance of structures in their offshore waters. Marine growth removal using high-pressure water is very common in the industry, but high-pressure water can easily damage and strip away anti-fouling coating. This smooth, slippery, and low-friction coating is what prevents organism growth from attaching to a subsea surface.
The objective of this project was to develop the technology necessary to remove marine growth from offshore structures using an ROV-operated system employing controlled cavitation erosion without damaging the anti-fouling coating. An ROV-mounted skid fitted a custom cavitation nozzle has been developed to perform this work.
A detailed quality test plan was created to analyze the system for subsea use for an operator in Angola. The primary goals of the Cavitation Water Jet System (CWJ) test plan were threefold:
Determine, for all nozzle sets operating at their rated pressure and flow, the optimum standoff distance, attack angle, and traverse rate necessary to remove simulated marine fouling without damaging the underlying coatings.
Determine the reaction forces generated from the lance and rotary head when operating at their rated pressure and flow rate. Since the rotary head can be fitted with two nozzle types operating at 8000 PSI @ 15 GPM and 5500 PSI @ 21 GPM respectively, the rotational speed for both was measured.
Determine the performance of system at different water depths.

The system passed quality tests and inspection, and was successfully used for FPSO hull cleaning in Angola in 2014-2015.
FLNG Projects Economics Improvement Based on Reliability Assessment
Authors: Benyessaad Olivier , Forte De Souza Karina , Le Diagon Vincent , Rocha Gustavo 
Published: April 2016

Abstract
With about 30 FLNG projects in planning, appraisal or FEED stage, the offshore industry is now diving in a new era. Even if the current oil price crisis is massively impacting new projects, gas projects remain a priority as it is considered by most of the energy analysts as the energy of the future for both, economical & environmental reasons. As no feedback is currently available, most of the operators are now looking towards the first units to be on stream to valid economic models based on unstable assumptions. This paper aims at demonstrating how reliability techniques such as RAM assessment can allow operators to adjust their economic model, ensure optimum return on investment and design reliable and safe installations. By using straight from concept stage of an FLNG project an adapted RAM tool coupled with an efficient RAM assessment based on experienced people, it will be possible to ensure design has been conducted effictively with respect to production performance and maintenance & repair strategy. Later on, by incorporating on a regular basis operational data comining from industy return on experience, companies will be able capitalize properly they experience and re-use it for future projects.
The paper will first give an overview of the (F)LNG market outlining the main challenges. Then, based on recent projects, it will detail the reliability methodology applied to ensure the profitability of such innovative installations. This section will focus on the key parameters and assumptions to be considered in order to assess production availability of the full FLNG installation in the most appropriate manner. Finally, after having pointed out the ins and outs of these analyses, a case study will be developed to quantify the benefit of the proposed approach.
Online Asset Integrity Management and Operational Optimisation Through Online Integrity Monitoring
Authors: Wallace Gary , Champlin Tom 
Published: April 2016

Abstract
This paper will focus on monitoring the integrity of fixed equipment in oil and gas production assets. The insight gained from a real time understanding of asset integrity enables enhanced evidence based operational decision making to improve safety and profitability. A case study and lessons learned from the use of online integrity monitoring systems will be given for upstream facilities.
Integrity Management Services for Floating Units from Design to Decommissioning
Authors: Boutrot Jonathan , Legregeois Nicolas 
Published: April 2016

By reviewing the process of Asset Integrity Management applied from the design phase, continued through the in-service life and obsolescence considerations for decommissioning, this paper presents a view of managing the safety and operational efficiency of floating structures.
The paper will go through the presentation of a didactic process ensuring the Asset Integrity of the structure in answering a few questions:
How to ensure a correct knowledge of the offshore facilities' condition?
What are the main degradation processes threatening the facilities?
What will be the response of a facility to the main threats over the years?
How to implement a cost-effective Inspection Strategy?

Answers to those questions will involve various services embedded into a global Integrity Management process such as CFD and hydrodynamics, structural FEM calculations, condition monitoring, Risk-Based Inspection strategy and 3D geometric models for visualization and reporting.
Established at design phase and updated during the in-service life of the Unit, this global Asset Integrity process for the structure will support and optimize the inspection programme based on risk considerations by focusing on the most critical elements to the safety.
Besides an OPEX cost reduction by optimizing the inspection efforts, the engineering services that are parts of the Asset Integrity Management are fully embedded into that global process. This brings another cut in costs by saving time and thus cost when performing engineering analysis.
A New Method to Design and Optimize the ICD for Horizontal Wells
Authors: Shi Hongfu , Zhou Haiyan , Hu Yong , He Yifan , Fu Rong , Ren Bo 
Published: April 2016

Abstract
QHD oilfield in Bohai Bay, China, is characterized by conventional heavy oil (average viscosity 150cp under reservoir conditions) with excellent reservoir quality (up to 30% porosity and 1-2D permeability) and strong aquifer. Horizontal and multilateral wells are widely used in QHD and most wells were standard completion. After 13 years of development, many wells show sharp production decline and rapid water cut increase. What's more, water breakthrough in several wells is much earlier than prediction. The high mobility ratio, hell-toe effect, bottom water, permeability heterogeneity and sand are contributed to reduced ultimate recovery and well life.
The use of ICD (inflow control device) is becoming more and more prevalent as it can delay the water break through and significantly improve the economic life of a well. This is especially important for offshore fields where well intervention is difficult and expensive. Therefore, ICD technique is proposed to address the above production problem while prolonging production life (BREKKE K, 1997).
In this paper, I discuss the feasibility of ICD for horizontal wells in heavy oil reservoir of offshore field. First, I analyze the actuality of the offshore heavy oil with strong bottom water in Bohai Bay and the reason of bottom water coning. Secondly, I discuss the feasibility of ICD for horizontal wells in heavy oil reservoir of offshore field. Finally, a new method is established to design the additional pressure of ICD. The method is compared to the uniform liquid method; what's more, a numerical model is developed to validate the new method. The production performance of the first ICD wells was discussed to provide evidence on its effectiveness and robustness. This has provided valuable data prior to well drilling and the final optimization of ICD.
The paper demonstrates the importance of seamless teamwork and coordination between reservoir engineers and project team to deliver superior performance. In a word, this paper is expected to assist well completion decisions for offshore heavy oil reservoir and to spark continue research on ICD.
Macondo and Bardolino: Two Case Studies of the Human Factors of Kick Detection Prior to a Blowout
Authors: St. John M. F. 
Published: April 2016

Abstract

Objectives
The Macondo and Bardolino incidents of 2009 and 2010 had similar beginnings but very different outcomes. While Macondo ended in disaster, Bardolino ended without a spill or injury. This case study of these two incidents analyzes and compares the human factors of detecting an influx or kick for each incident.

Methods
A set of 147 human factors issues involved in kick detection were assessed, first in aggregate, and then in terms of a step by step narrative of each incident. Next, patterns among the human factors were identified by determining which factors tend to cluster together across a set of 43 incidents. Some factors tend to co-occur with other issues.

Results
These clusters of co-occurring issues form two general themes which can be described as a general wariness toward well control versus early engagement and investigation, such as stopping to check for flow. The wariness cluster is more closely associated with shutting in the well early, which is an important objective of safe well control practice. However, a human factors barrier associated with the engagement cluster, considering the possibility of an influx, may have led to the turning point between the Macondo and Bardolino incidents.

Novel information
These analyses point to promising locations to focus attention, both for assessing rigs prior to incidents, during investigations after incidents, and most importantly, for researching and developing new technologies and procedures for minimizing or precluding incidents all together.
CFD Simulation of Current Past Bluff Body at High Reynolds Number
Authors: Ibrahim Ahmed , Huang Chen-Pey , Korpus Richard , Dalton Charles 
Published: April 2016

Abstract
Strong ocean currents flowing past bluff offshore structures such as semisubmersibles and tension-leg platforms (TLP) can instigate large amplitude vortex-induced motion (VIM). This can lead to significant fatigue loads on the mooring system and its attachments. Simulating this problem numerically is of particular interest to the offshore industry in order to determine design loads and to avoid or suppress motion and vibration of the structure. But despite this being a classical flow problem, it remains a major numerical challenge, particularly at high Reynolds numbers where most offshore platforms operate. The difficulty arises from the strong nonlinear nature of the governing Navier-Stokes equations and the unsteady turbulent nature of the physical flow itself.
This study was therefore conducted to identify best practices for using Computational Fluid Dynamics (CFD) to estimate the loads imposed by uniform currents past a stationary bluff body (representing a semisubmersible column). Several Reynolds numbers were chosen to cover the subcritical, transcritical, and supercritical flow regimes. Two Reynolds-Averaged Navier-Stokes (RANS) software packages were used, the open source code OpenFOAM and the commercial code STAR-CCM+.
Verification of the numerical model and validation of results against published experimental test data is presented and the implications discussed. The paper provides several key elements that should be considered when modeling a uniform current past bluff body at high Reynolds number.
Flow Assurance Design Considerations for Umbilical Riser Base Gas Lift System
Authors: McDermott Chris , Ike Shirley , Braniff Martin 
Published: April 2016

Abstract
Riser Base Gas Lift is one of several methods successfully deployed that can enhance production and suppress severe slugging. With few moving parts, it is a solution that can be accommodated into existing infrastructure with minimal upgrades on existing facilities while not being as maintenance intensive as other solutions. The flow assurance design is critical to successful implementation and this paper details this process through the means of a case study.
The case study in question is a three well, deep water subsea tie-back. The subsea system consists of an 8" × 12" pipe-in-pipe round-trip piggable flowline loop which will experience severe terrain slugging. Riser base gas lift had been implemented with success on adjacent fields at this facility; therefore it was again selected for deployment. From a Flow Assurance perspective, design considerations discussed are: Optimum Injection Rate/Operating Range: Flowrate requirements that will effectively mitigate slugging and will not violate any operating constraints.Low Temperature Mitigation: Design against brittle material failure.Erosion Control: Assessment of droplet erosion.Production Chemistry: Design to prevent formation of hydrates/asphaltenes in the production system due to injection of gas.Testing/Benchmarking: Since system design is heavily dependent on the accuracy of simulation modelling, details of equipment flow tests to validate performance are discussed.Recommendations/Support to Operations: Development of standard operating practices associated with gas lift.Execution Issues: Detailing design adaptations to system changes during installation etc.Revalidation: Review of actual operational performance against design intent.
For this field, a novel technological solution of a gas-lift umbilical riser was selected. This configuration provides the best balance of operability, reliability and cost. The operating philosophy uses a fixed subsea orifice /topside choke to control the gas flow (rather than the conventional variable subsea choke). The orifice will regulate the injection rate even as the system pressure varies due to slugging, allowing the umbilical to act as an accumulator that dampens the pressure variations and allows for a larger bandwidth and smoother operation. Ultimately this configuration is envisioned to be less dependent on operator interaction.
Real Time Observing and Forecasting of Loop Currents in 2015
Authors: Cooper C. , Danmeier D. , Frolov S. , Stuart G. , Zuckerman S. , Anderson S. , Sharma N. 
Published: April 2016

Abstract
From February to June 2015, the Loop Current and its associated eddies were monitored at an unprecedented rate in southern Walker Ridge using traditional satellite sensors, satellite-tracked Lagrangian buoys, ship-mounted ADCPs, and moored ADCPs. In addition, a newly developed aerial system known as the Remote Ocean Current Imaging System (ROCIS) was flown almost daily, measuring surface currents at roughly 1 km spatial resolution over 125,000 km of combined transects. During the five-month period of observations, the Loop was extremely active, shedding one large and a second smaller anticyclone, and generating numerous intense cyclones. The extensive observations offered the opportunity to improve model initialization and thus the overall accuracy of the operational ocean current forecasts. An example is given of the substantial improvements that can result when more accurate observations are feed into the model initialization process. Perhaps just as importantly, the synoptic observations provided forecasters with an unprecedented view of the important fronts and features dominating the local flow field. The paper reviews the forecast accuracy from a numerical model and the subjective predictions from two forecasting groups with access to the model. The results show the model has about equal skill to the best of the forecasters. Mean 48-hr forecast error for the best forecaster was only about 0.2 kn but the variability of the error was substantial, 0.6 kn, with a correlation coefficient of only 0.65. In short, forecasting currents when the Loop or eddy fronts are nearby is challenging even with intense measurements and modeling. Those who depend on such forecasts should maintain realistic expectations regarding the forecast accuracy.